The third free product presentation event on 19th May 2009 in New Jersey, US
With the positive feedback of first two presentations and to meet the increasing demand of training request, Top Tech has planned to hold the third presentation on May. This event is specially designed for IT consultants, IT services engineers, and computer repair stores owners who are determined to expand their business during this discouraging economic situation.
Detailed schedule of presentation:
Time: Tuesday May 19, 2009. From 9:00 am to 5:00 pmLocation: PC Warehouse, 3681 US Highway 9, Suite 25, Freehold, NJ 07728 (Located in the Freehold Mall)
Training outline:
1. The definition of broad sense Data Recovery, what is our pioneered 3+1 data recovery flow
2. Data Recovery tools available in market, what is the pros and cons respectively
3. Data Compass presentation (include the function, advantage and core technologies)
4. Data Compass live presentation (case study)
5. HD Doctor Suite presentation (include live case study , function, skills,)
6. HD Doctor Suite live presentation (case Study)
7. Hands on experience and case studies, you can bring your own defective HDDs for test.8. Ask questions
Top Tech has been our authorized Data Compass reseller, training partner and service provider since November 2008. Due to Data Compass’s satisfied performance and excellent after-sale service, Top Tech has achieved a great success. On the basis of mutual benefit and bring the real time service advantage to customers, Top tech and SalvationDATA both agreed that Top tech will take care of distribution, presentation/training, and support services for SalvationDATA products in eastern US.
Get to know more details about this free presentation, please kindly call us at (0086) 28 6859 9758 or email us at usinfo@salvationdata.com. And also you can directly contact our reseller in New Jersey: Tel: 001-732-866-9799, email: sddcusa@msn.com
Information about the second presentation survey form which completed by the attendees, please take a look at http://www.salvationdata.com/news/20090220.htm
Tuesday, May 5, 2009
Thursday, April 23, 2009
One Successful Story from One of My Client
Today, it is bright and breezy. I would like to share one successful story with all of you. Mike is one of my favorite client in US, from PC Recovery Lab. He is a pro and gave us a lot of useful suggestion. I am very thankful for his testing report. Well, He bought Data Compass in August from me.
Recently, he updated his standard version into premier one, with RAID recovery function inside it. He is very happy with the new v5.0 DC program. Below is the email from him. If anyone has data recovery problems, you can contact him at:
PC RECOVERY LAB
2508-A Johnston Street Lafayette, LA
70503 +1-337-326-4295 Tel
+1-877-470-9652 Fax
Original Email from Mike:
hi,Laura
I wish to share BOTH Good and Bad. Not always only the problems, but also the successes. Today we received 2 Raptor HDD in RAID 0. We decide to try to build ARRAY with new DC 5.0 . We succeeded. So, we decided to share with you the positive success story.
:)
Fourth generation data recovery software tools conquer the global market
Fourth generation data recovery software tools conquer the global market
(chinadaily.com.cn)Updated: 2009-04-23 14:23
In 2009, the term data recovery is gradually becoming a hot topic for IT users. Due to the aggravation of data loss caused by successive natural catastrophes in recent years, the technology of data recovery tools has become a huge focus in the information security field by retrieving billions of losses and showing its power strength to IT users who have suffered data loss. This technology has built a solid and secure defense line for the computer information security field, data backup and data recovery.
Data recovery can only be performed with the help of data recovery tools. However, few people, except professional technicians, are aware of how data recovery tools work. The following author's guide will help you understand the main force of data recovery work and data recovery tools.
Let's look at the development process of data recovery tools, including the process from sole logical data recovery to overall data recovery, which covers logical, firmware and physical levels containing four generations' worth of evolution.
The first generation consists of logical data recovery software which works in DOS mode and can make revisions to hex. Typical data recovery tool: PCTOOLS9. In the second generation, data recovery tools can work in Windows version to handle automatic recovery for partition loss and file deletion. Typical tools: EASYRECOVERY, R-STUDIO, WINHEX. Data recovery tools in the third generation are software or equipment which can tackle logical and firmware data recovery. Representatives: hard disk firmware and bad sector repair Program (HD Doctor Suite) from SalvationDATA and PC3000 hard disk repair cards. In the fourth generation, data recovery tools have evolved into integrated equipment for logical, firmware and physical recovery with the typical example: SalvationDATA Data Compass.
In the past, due to the limitation of technology data recovery tools in the first three generations all had sole function defects, complicated operation and low recovery success rates; this caused many unsolved problems in the data recovery field. The current success rate hovers at 80 percent and has made no progress for several years. As a result, fourth-generation data recovery tools came into being. Tools in this generation feature single click solutions with high intelligentized built-in features to combat the latest problems, and USB movable recovery features. In addition, all fourth generation tools feature high intelligentized design as well as easy operation. First-time users can operate the tools smoothly after learning them in only one day.
In the following, the author will introduce a new member to the data recovery field—the fourth generation data recovery tool which takes Data Compass (DC) as a representative. This tool marks the advent of the movable data recovery era, where the biggest advantage is that data recovery companies can use the tools to provide in-house service and involve customers in the entire process to prevent theft and wrongful distribution of important customer data.
DC, developed by SalvationDATA-State hi-tech enterprise, adopts the innovative design concept which comes from years' of data recovery experience. All the parameters are higher than other data recovery tools in the present market and can support nearly all hard disks from different manufacturers with large capabilities.
According to the development department, "DC is mainly designed for hard disks with severe bad sectors, damaged heads (including partial head damage or instable head after head swap) and RAID recovery. In the future, DC will support data recovery from various types of storage mediums, such as, USB sticks, SSD flash disks, etc. Its features of easy operation and short learning time dramatically reduce the requirement of user's expertise."
It is estimated that there are many professional data recovery companies who are using Data Compass since its first trial, and who are giving it high praise. As of March 2009, there were approximately 300 companies who were using Data Compass to complete hundreds and thousands of difficult tasks, including: Top Tech in the United States, MICRO MANAGEMENT SRL in Italy, RSE data recovery services in the Netherlands, Kroll Ontrack in Germany, Datatrack-Labs in the UK, Data Recovery in Sweden, Internet Owners Corporation in Japan, Stellar in India, etc. Besides being widely used in the data recovery field, Data Compass greatly contributes to computer forensics, education and training. Presently, Data Compass is the tool applied in training conducted by American data recovery specialist Mr. Scott. It is also the first tool chosen in assisting UK data recovery and training company Data Clinic and Italian Data recovery and training company MICRO MANAGEMENT SRL to provide professional data recovery services and training to people around the world. In a forthcoming demo in Milan held by Italy MICRO MANAGEMENT SRL, Data Compass will again reveal its powerful strength.
"Data Compass data recovery tools helps us to restore data from hard drives suffering from severe bad sectors, which are not able to be recovered with other tools in the DR market. By using the advanced Service Area (SA) emulation technology especially, it accesses the data from firmware defective hard drives directly. Also, multiple settings of the reading algorithm enable the optimization of data recovery from hard drives with poor performance of Head & Disk Assembly (HDA)", Zijian Xie, Research and Development Manager of UK Computer science labs, said.
We believe that the fifth and sixth generation data recovery tools will be created with SalvationDATA in the near future to help retrieve lost data for customers maximally. Which features will be contained in these tools? We'll have to wait and see what those future miracles will be.
(For more biz stories, please visit Industries)
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Wednesday, April 22, 2009
Flash Doctor
20/04/2009
Since we announced our "SalvationDATA Universal Flash Recovery device" project (please refer to http://www.salvationdata.com/news/20090206.htm), we have been receiving emails of requests from our customers, also we've noticed that there were numerous discussions on this coming product on the forums. We truly understood the urgent need of a reliable flash recovery tool which covers a comprehensive flash device controllers, since there wasn't one available.
Today we are releasing an update on this product. Please visit us at the following link:
http://www.salvationdata.com/blog/update-on-salvationdata-universal-flash-recovery-device-flash-doctor/
SalvationDATA Team
Since we announced our "SalvationDATA Universal Flash Recovery device" project (please refer to http://www.salvationdata.com/news/20090206.htm), we have been receiving emails of requests from our customers, also we've noticed that there were numerous discussions on this coming product on the forums. We truly understood the urgent need of a reliable flash recovery tool which covers a comprehensive flash device controllers, since there wasn't one available.
Today we are releasing an update on this product. Please visit us at the following link:
http://www.salvationdata.com/blog/update-on-salvationdata-universal-flash-recovery-device-flash-doctor/
SalvationDATA Team
Monday, April 20, 2009
Update on SalvationDATA Universal Flash Recovery device - Flash Doctor
Update on SalvationDATA Universal Flash Recovery device - Flash Doctor
Since we announced our "SalvationDATA Universal Flash Recovery device" project (please refer to http://www.salvationdata.com/news/20090206.htm), we have been receiving emails of requests from our customers, also we've noticed that there were numerous discussions on this coming product on the forums. We truly understood the urgent need of a reliable flash recovery tool which covers a comprehensive flash device controllers, since there wasn't one available.
Today we are releasing an update on this product:1. The name of the product will be Flash Doctor; it will a stand-alone, hardware-software complex product specialized for data recovery from NAND flash chips.
2. According to the countless experiments and real cases sent by the customers (who own flash recovery tools from other companies but didn't manage to work it through), our success rate by now is around 50%-60% (please note that this is a result from all flash chips with all kinds of controller types we found and received, not from specific chips with specific controller types), of course we will continue working on it for improvement. But by now we can say we are at least several times powerful than other tools from other companies.
3. A model (sample) of the hardware included in the complex is also released. It reads the NAND interface chips and works through a USB cable connects to the computer, which has the software of the complex installed.
Since we announced our "SalvationDATA Universal Flash Recovery device" project (please refer to http://www.salvationdata.com/news/20090206.htm), we have been receiving emails of requests from our customers, also we've noticed that there were numerous discussions on this coming product on the forums. We truly understood the urgent need of a reliable flash recovery tool which covers a comprehensive flash device controllers, since there wasn't one available.
Today we are releasing an update on this product:1. The name of the product will be Flash Doctor; it will a stand-alone, hardware-software complex product specialized for data recovery from NAND flash chips.
2. According to the countless experiments and real cases sent by the customers (who own flash recovery tools from other companies but didn't manage to work it through), our success rate by now is around 50%-60% (please note that this is a result from all flash chips with all kinds of controller types we found and received, not from specific chips with specific controller types), of course we will continue working on it for improvement. But by now we can say we are at least several times powerful than other tools from other companies.
3. A model (sample) of the hardware included in the complex is also released. It reads the NAND interface chips and works through a USB cable connects to the computer, which has the software of the complex installed.
Wednesday, April 15, 2009
Approach to Raid Data Recovery
Approach to Raid Data Recovery
—How to recover a Raid 5EE Case
As we all know, in 1987, Patterson, Gibson and Katz at the University of California Berkeley, published a paper entitled "A Case for Redundant Arrays of Inexpensive Disks (RAID)". This paper described various types of disk arrays, referred to by the acronym RAID. The basic idea of RAID was to combine multiple small, inexpensive disk drives into an array of disk drives which yields performance exceeding that of a Single Large Expensive Drive (SLED). Additionally, this array of drives appears to the computer as a single logical storage unit or drive.
The Mean Time Between Failure (MTBF) of the array will be equal to the MTBF of an individual drive, divided by the number of drives in the array. Because of this, the MTBF of an array of drives would be too low for many application requirements. However, disk arrays can be made fault-tolerant by redundantly storing information in various ways.
Five types of array architectures, RAID-1 through RAID-5, were defined by the Berkeley paper, each providing disk fault-tolerance and each offering different trade-offs in features and performance. In addition to these five redundant array architectures, it has become popular to refer to a non-redundant array of disk drives as a RAID-0 array.
Data Striping
Fundamental to RAID is "striping", a method of concatenating multiple drives into one logical storage unit. Striping involves partitioning each drive's storage space into stripes which may be as small as one sector (512 bytes) or as large as several megabytes. These stripes are then interleaved round-robin, so that the combined space is composed alternately of stripes from each drive. In effect, the storage space of the drives is shuffled like a deck of cards. The type of application environment, I/O or data intensive, determines whether large or small stripes should be used.
Most multi-user operating systems today, like NT, Unix and Netware, support overlapped disk I/O operations across multiple drives. However, in order to maximize throughput for the disk subsystem, the I/O load must be balanced across all the drives so that each drive can be kept busy as much as possible. In a multiple drive system without striping, the disk I/O load is never perfectly balanced. Some drives will contain data files which are frequently accessed and some drives will only rarely be accessed. In I/O intensive environments, performance is optimized by striping the drives in the array with stripes large enough so that each record potentially falls entirely within one stripe. This ensures that the data and I/O will be evenly distributed across the array, allowing each drive to work on a different I/O operation, and thus maximize the number of simultaneous I/O operations which can be performed by the array.
In data intensive environments and single-user systems which access large records, small stripes (typically one 512-byte sector in length) can be used so that each record will span across all the drives in the array, each drive storing part of the data from the record. This causes long record accesses to be performed faster, since the data transfer occurs in parallel on multiple drives. Unfortunately, small stripes rule out multiple overlapped I/O operations, since each I/O will typically involve all drives. However, operating systems like DOS which do not allow overlapped disk I/O, will not be negatively impacted. Applications such as on-demand video/audio, medical imaging and data acquisition, which utilize long record accesses, will achieve optimum performance with small stripe arrays.
A potential drawback to using small stripes is that synchronized spindle drives are required in order to keep performance from being degraded when short records are accessed. Without synchronized spindles, each drive in the array will be at different random rotational positions. Since an I/O cannot be completed until every drive has accessed its part of the record, the drive which takes the longest will determine when the I/O completes. The more drives in the array, the more the average access time for the array approaches the worst case single-drive access time. Synchronized spindles assure that every drive in the array reaches its data at the same time. The access time of the array will thus be equal to the average access time of a single drive rather than approaching the worst case access time.
The different RAID levels
RAID-0
RAID Level 0 is not redundant, hence does not truly fit the "RAID" acronym. In level 0, data is split across drives, resulting in higher data throughput. Since no redundant information is stored, performance is very good, but the failure of any disk in the array results in data loss. This level is commonly referred to as striping.
RAID-1
RAID Level 1 provides redundancy by writing all data to two or more drives. The performance of a level 1 array tends to be faster on reads and slower on writes compared to a single drive, but if either drive fails, no data is lost. This is a good entry-level redundant system, since only two drives are required; however, since one drive is used to store a duplicate of the data, the cost per megabyte is high. This level is commonly referred to as mirroring.
RAID-2
RAID Level 2, which uses Hamming error correction codes, is intended for use with drives which do not have built-in error detection. All SCSI drives support built-in error detection, so this level is of little use when using SCSI drives.
RAID-3
RAID Level 3 stripes data at a byte level across several drives, with parity stored on one drive. It is otherwise similar to level 4. Byte-level striping requires hardware support for efficient use.
RAID-4
RAID Level 4 stripes data at a block level across several drives, with parity stored on one drive. The parity information allows recovery from the failure of any single drive. The performance of a level 4 array is very good for reads (the same as level 0). Writes, however, require that parity data be updated each time. This slows small random writes, in particular, though large writes or sequential writes are fairly fast. Because only one drive in the array stores redundant data, the cost per megabyte of a level 4 array can be fairly low.
RAID-5
RAID Level 5 is similar to level 4, but distributes parity among the drives. This can speed small writes in multiprocessing systems, since the parity disk does not become a bottleneck. Because parity data must be skipped on each drive during reads, however, the performance for reads tends to be considerably lower than a level 4 array. The cost per megabyte is the same as for level
RAID-5EE
Since our case study is for a RAID 5EE case, so we need to get to understand RAID level-5EE
(Note: This feature is not supported on all controllers.)
RAID level-5EE is similar to RAID level-5E but with a more efficient distributed spare and faster rebuild times. Like RAID level-5E, this RAID level stripes data and parity across all of the drives in the array.
RAID level-5EE offers both data protection and increased throughput. When an array is assigned RAID level-5EE, the capacity of the logical drive is reduced by the capacity of two physical drives in the array: one for parity and one for the spare.
The spare drive is part of the RAID level-5EE array. However, unlike RAID level-5E, which uses contiguous free space for the spare, a RAID level-5EE spare is interleaved with the parity blocks, as shown in the following example. This allows data to be reconstructed more quickly if a physical drive in the array fails. With such a configuration, you cannot share the spare drive with other arrays. If you want a spare drive for any other array, you must have another spare drive for those arrays.
RAID level-5EE requires a minimum of four drives and, depending upon the level of firmware and the stripe-unit size, supports a maximum of 8 or 16 drives. RAID level-5EE is also firmware-specific.
The following illustration is an example of a RAID level-5EE logical drive.
RAID level-5EE example
Start with four physical drives.
Create an array using all four physical drives.
Then create a logical drive within the array.
The data is striped across the drives, creating blocks in the logical drive. The storage of the data parity (denoted by *) is striped, and it shifts from drive to drive as it does in RAID level-5E. The spare drive (denoted by S) is interleaved with the parity blocks, and it also shifts from drive to drive.
If a physical drive fails in the array, the data from the failed drive is reconstructed. The array undergoes compaction, and the distributed spare drive becomes part of the array. The logical drive remains RAID level-5EE.
When you replace the failed drive, the data for the logical drive undergoes expansion and returns to the original striping scheme.
Advantages and disadvantages
RAID level-5EE offers the following advantages and disadvantages.
Advantages
· 100% data protection
· Offers more physical drive storage capacity than RAID level-1 or level-1E
· Higher performance than RAID level-5
· Faster rebuild than RAID level-5E
Disadvantages
· Lower performance than RAID level-1 and level-1E
· Supports only one logical drive per array
· Cannot share a hot-spare drive with other arrays
· Not supported on all controllers
Recently, we successfully retrieved data from it by using Data Compass from SalvationDATA.
Firstly, you need image all the drives into files. Then run the Data Compass Controller and Program:
In Data Compass, RAID utility supports both “automatic mode” and “manual mode” of analysis. We will introduce how to analyze a RAID 5EE system in automatic mode first:
Select Analysis Mode
First select the analyzing mode; then we only need to define the Number of Segment Disks (the original number of disks in the RAID system), RAID Type and RAID Manufacturer. In this example, we have 4 segment disks, RAID type is RAID 5EE and from MANUFACTURER_Standard
Please Note: the IBM RAID controller is SNIA Compatible; all manufacturers belong to MANUFACTURER_Standard, aside from AMI, HP/COMPAQ and DYNAMIC Disk.
The next step is to import RAID segment disks, they can be disk image or physical disk; in automatic mode, users can import the segment disks by random sequence, the program will work out the actual order.
Import Segment Disks
Click “Apply’’ after importing all the segment disks, then program will analyze segment disk sequence and the storage method according to these setting information, and return with all parameters.
Analysis Finishes
Remark: How to understand the returned HDD sequence
HD0, HD1, HD2 and HD3 on the left side represents the importing sequence of the segment disks (this sequence means nothing indeed); 3.1.2.0 on the right side represents the native sequence of the segment disks. For example, the native segment sequence in this case study is 3.1.2.0, which means the segment you imported as HD3 is actually the first segment disk in the RAID system, HD1 is the 2rd, HD2 the 3rd and HD0 the 4th.
By clicking the OK button next to the “Apply” and “Stop” button, program will try to open the virtually created RAID system and display the partitions and files in the DCEXP interface.
Partition of the RAID system shows up in DCEXP
Double click the needed partition, and double click ROOT to show folders and files.
Now users can recover the needed files just like recovering data from a normal HDD.
Second, we will introduce how to analyze a RAID 5EE system in manual mode:
When select Manual Setting, all the parameters should be set manually and you need to know the native sequence of the segment disks (in case you don’t know, work it out by trial and error) and other parameters marked in red frame. In this case, the Number of Segment Disks should be 4, with RAID Type 5EE. Manufacturer Standard, Block Order is RIGHT_ASYNCHRONOUS and Stripe Size is 8KB.
Attention:
1. The IBM RAID controller is SNIA Compatible; all manufacturers belong to MANUFACTURER_Standard, aside from AMI, HP/COMPAQ and DYNAMIC Disk.
2. Delay is only available in HP/COMPAQ RAID system; users don’t need to set this option for RAID system of other manufactures.
3. For all the RAID system of HP/COMPAQ and some of other manufactures, users need to set Header Size for analysis. The Header Size need to match different RAID system and users normally set it by trial and error according to experience. In this case we don’t need to set the header size, because there is no Header Size (offset) in this RAID system.
After that, import the segment disks exactly in the native sequence. In this case, the third segment drive was lost.
After setting, click “Apply” button and wait until you receive the below message:
By clicking the OK button next to the “Apply” and “Stop” button, program will try to open the virtually created RAID system and display the partitions and files in the DCEXP interface.
Attention: If the parameter set is incorrect and program can’t acquire the partition, users need to reset the parameter and try again *(Manual Mode is a process of trial and error).
Double click the needed partition, and double click ROOT to show folders and files.
Now users can recover the needed files just like recovering data from a normal HDD.
From the above case study, we know that the basic steps to recover a RAID case. Nowadays, the Raid is widely used by corporations, and large businesses, the storage efficiency is raised thank to this technology. But it doesn’t mean it is worry free for our crucial data. Data Recovery is remedial way and our last choice of no choice. The key of data security is BACKUP, no other shortcuts.
—How to recover a Raid 5EE Case
As we all know, in 1987, Patterson, Gibson and Katz at the University of California Berkeley, published a paper entitled "A Case for Redundant Arrays of Inexpensive Disks (RAID)". This paper described various types of disk arrays, referred to by the acronym RAID. The basic idea of RAID was to combine multiple small, inexpensive disk drives into an array of disk drives which yields performance exceeding that of a Single Large Expensive Drive (SLED). Additionally, this array of drives appears to the computer as a single logical storage unit or drive.
The Mean Time Between Failure (MTBF) of the array will be equal to the MTBF of an individual drive, divided by the number of drives in the array. Because of this, the MTBF of an array of drives would be too low for many application requirements. However, disk arrays can be made fault-tolerant by redundantly storing information in various ways.
Five types of array architectures, RAID-1 through RAID-5, were defined by the Berkeley paper, each providing disk fault-tolerance and each offering different trade-offs in features and performance. In addition to these five redundant array architectures, it has become popular to refer to a non-redundant array of disk drives as a RAID-0 array.
Data Striping
Fundamental to RAID is "striping", a method of concatenating multiple drives into one logical storage unit. Striping involves partitioning each drive's storage space into stripes which may be as small as one sector (512 bytes) or as large as several megabytes. These stripes are then interleaved round-robin, so that the combined space is composed alternately of stripes from each drive. In effect, the storage space of the drives is shuffled like a deck of cards. The type of application environment, I/O or data intensive, determines whether large or small stripes should be used.
Most multi-user operating systems today, like NT, Unix and Netware, support overlapped disk I/O operations across multiple drives. However, in order to maximize throughput for the disk subsystem, the I/O load must be balanced across all the drives so that each drive can be kept busy as much as possible. In a multiple drive system without striping, the disk I/O load is never perfectly balanced. Some drives will contain data files which are frequently accessed and some drives will only rarely be accessed. In I/O intensive environments, performance is optimized by striping the drives in the array with stripes large enough so that each record potentially falls entirely within one stripe. This ensures that the data and I/O will be evenly distributed across the array, allowing each drive to work on a different I/O operation, and thus maximize the number of simultaneous I/O operations which can be performed by the array.
In data intensive environments and single-user systems which access large records, small stripes (typically one 512-byte sector in length) can be used so that each record will span across all the drives in the array, each drive storing part of the data from the record. This causes long record accesses to be performed faster, since the data transfer occurs in parallel on multiple drives. Unfortunately, small stripes rule out multiple overlapped I/O operations, since each I/O will typically involve all drives. However, operating systems like DOS which do not allow overlapped disk I/O, will not be negatively impacted. Applications such as on-demand video/audio, medical imaging and data acquisition, which utilize long record accesses, will achieve optimum performance with small stripe arrays.
A potential drawback to using small stripes is that synchronized spindle drives are required in order to keep performance from being degraded when short records are accessed. Without synchronized spindles, each drive in the array will be at different random rotational positions. Since an I/O cannot be completed until every drive has accessed its part of the record, the drive which takes the longest will determine when the I/O completes. The more drives in the array, the more the average access time for the array approaches the worst case single-drive access time. Synchronized spindles assure that every drive in the array reaches its data at the same time. The access time of the array will thus be equal to the average access time of a single drive rather than approaching the worst case access time.
The different RAID levels
RAID-0
RAID Level 0 is not redundant, hence does not truly fit the "RAID" acronym. In level 0, data is split across drives, resulting in higher data throughput. Since no redundant information is stored, performance is very good, but the failure of any disk in the array results in data loss. This level is commonly referred to as striping.
RAID-1
RAID Level 1 provides redundancy by writing all data to two or more drives. The performance of a level 1 array tends to be faster on reads and slower on writes compared to a single drive, but if either drive fails, no data is lost. This is a good entry-level redundant system, since only two drives are required; however, since one drive is used to store a duplicate of the data, the cost per megabyte is high. This level is commonly referred to as mirroring.
RAID-2
RAID Level 2, which uses Hamming error correction codes, is intended for use with drives which do not have built-in error detection. All SCSI drives support built-in error detection, so this level is of little use when using SCSI drives.
RAID-3
RAID Level 3 stripes data at a byte level across several drives, with parity stored on one drive. It is otherwise similar to level 4. Byte-level striping requires hardware support for efficient use.
RAID-4
RAID Level 4 stripes data at a block level across several drives, with parity stored on one drive. The parity information allows recovery from the failure of any single drive. The performance of a level 4 array is very good for reads (the same as level 0). Writes, however, require that parity data be updated each time. This slows small random writes, in particular, though large writes or sequential writes are fairly fast. Because only one drive in the array stores redundant data, the cost per megabyte of a level 4 array can be fairly low.
RAID-5
RAID Level 5 is similar to level 4, but distributes parity among the drives. This can speed small writes in multiprocessing systems, since the parity disk does not become a bottleneck. Because parity data must be skipped on each drive during reads, however, the performance for reads tends to be considerably lower than a level 4 array. The cost per megabyte is the same as for level
RAID-5EE
Since our case study is for a RAID 5EE case, so we need to get to understand RAID level-5EE
(Note: This feature is not supported on all controllers.)
RAID level-5EE is similar to RAID level-5E but with a more efficient distributed spare and faster rebuild times. Like RAID level-5E, this RAID level stripes data and parity across all of the drives in the array.
RAID level-5EE offers both data protection and increased throughput. When an array is assigned RAID level-5EE, the capacity of the logical drive is reduced by the capacity of two physical drives in the array: one for parity and one for the spare.
The spare drive is part of the RAID level-5EE array. However, unlike RAID level-5E, which uses contiguous free space for the spare, a RAID level-5EE spare is interleaved with the parity blocks, as shown in the following example. This allows data to be reconstructed more quickly if a physical drive in the array fails. With such a configuration, you cannot share the spare drive with other arrays. If you want a spare drive for any other array, you must have another spare drive for those arrays.
RAID level-5EE requires a minimum of four drives and, depending upon the level of firmware and the stripe-unit size, supports a maximum of 8 or 16 drives. RAID level-5EE is also firmware-specific.
The following illustration is an example of a RAID level-5EE logical drive.
RAID level-5EE example
Start with four physical drives.
Create an array using all four physical drives.
Then create a logical drive within the array.
The data is striped across the drives, creating blocks in the logical drive. The storage of the data parity (denoted by *) is striped, and it shifts from drive to drive as it does in RAID level-5E. The spare drive (denoted by S) is interleaved with the parity blocks, and it also shifts from drive to drive.
If a physical drive fails in the array, the data from the failed drive is reconstructed. The array undergoes compaction, and the distributed spare drive becomes part of the array. The logical drive remains RAID level-5EE.
When you replace the failed drive, the data for the logical drive undergoes expansion and returns to the original striping scheme.
Advantages and disadvantages
RAID level-5EE offers the following advantages and disadvantages.
Advantages
· 100% data protection
· Offers more physical drive storage capacity than RAID level-1 or level-1E
· Higher performance than RAID level-5
· Faster rebuild than RAID level-5E
Disadvantages
· Lower performance than RAID level-1 and level-1E
· Supports only one logical drive per array
· Cannot share a hot-spare drive with other arrays
· Not supported on all controllers
Recently, we successfully retrieved data from it by using Data Compass from SalvationDATA.
Firstly, you need image all the drives into files. Then run the Data Compass Controller and Program:
In Data Compass, RAID utility supports both “automatic mode” and “manual mode” of analysis. We will introduce how to analyze a RAID 5EE system in automatic mode first:
Select Analysis Mode
First select the analyzing mode; then we only need to define the Number of Segment Disks (the original number of disks in the RAID system), RAID Type and RAID Manufacturer. In this example, we have 4 segment disks, RAID type is RAID 5EE and from MANUFACTURER_Standard
Please Note: the IBM RAID controller is SNIA Compatible; all manufacturers belong to MANUFACTURER_Standard, aside from AMI, HP/COMPAQ and DYNAMIC Disk.
The next step is to import RAID segment disks, they can be disk image or physical disk; in automatic mode, users can import the segment disks by random sequence, the program will work out the actual order.
Import Segment Disks
Click “Apply’’ after importing all the segment disks, then program will analyze segment disk sequence and the storage method according to these setting information, and return with all parameters.
Analysis Finishes
Remark: How to understand the returned HDD sequence
HD0, HD1, HD2 and HD3 on the left side represents the importing sequence of the segment disks (this sequence means nothing indeed); 3.1.2.0 on the right side represents the native sequence of the segment disks. For example, the native segment sequence in this case study is 3.1.2.0, which means the segment you imported as HD3 is actually the first segment disk in the RAID system, HD1 is the 2rd, HD2 the 3rd and HD0 the 4th.
By clicking the OK button next to the “Apply” and “Stop” button, program will try to open the virtually created RAID system and display the partitions and files in the DCEXP interface.
Partition of the RAID system shows up in DCEXP
Double click the needed partition, and double click ROOT to show folders and files.
Now users can recover the needed files just like recovering data from a normal HDD.
Second, we will introduce how to analyze a RAID 5EE system in manual mode:
When select Manual Setting, all the parameters should be set manually and you need to know the native sequence of the segment disks (in case you don’t know, work it out by trial and error) and other parameters marked in red frame. In this case, the Number of Segment Disks should be 4, with RAID Type 5EE. Manufacturer Standard, Block Order is RIGHT_ASYNCHRONOUS and Stripe Size is 8KB.
Attention:
1. The IBM RAID controller is SNIA Compatible; all manufacturers belong to MANUFACTURER_Standard, aside from AMI, HP/COMPAQ and DYNAMIC Disk.
2. Delay is only available in HP/COMPAQ RAID system; users don’t need to set this option for RAID system of other manufactures.
3. For all the RAID system of HP/COMPAQ and some of other manufactures, users need to set Header Size for analysis. The Header Size need to match different RAID system and users normally set it by trial and error according to experience. In this case we don’t need to set the header size, because there is no Header Size (offset) in this RAID system.
After that, import the segment disks exactly in the native sequence. In this case, the third segment drive was lost.
After setting, click “Apply” button and wait until you receive the below message:
By clicking the OK button next to the “Apply” and “Stop” button, program will try to open the virtually created RAID system and display the partitions and files in the DCEXP interface.
Attention: If the parameter set is incorrect and program can’t acquire the partition, users need to reset the parameter and try again *(Manual Mode is a process of trial and error).
Double click the needed partition, and double click ROOT to show folders and files.
Now users can recover the needed files just like recovering data from a normal HDD.
From the above case study, we know that the basic steps to recover a RAID case. Nowadays, the Raid is widely used by corporations, and large businesses, the storage efficiency is raised thank to this technology. But it doesn’t mean it is worry free for our crucial data. Data Recovery is remedial way and our last choice of no choice. The key of data security is BACKUP, no other shortcuts.
Sunday, April 12, 2009
New version of Data Compass UDMA (Windows) released!-
New version of Data Compass UDMA (Windows) released!- All registered users of the client forum can download this update right now!
The new version 5.00 Data Compass Package
------ Update Log for v5.00 ------Date: 2009-4-13Current Version: 5.00
1. New feature: Drive Cache Repair has been appended. Drive cache malfunction has been a typical problem for Maxtor HDD and Seagate Barracuda 7200.7 and 7200.11 HDD, which manifests itself as the following: Hard drive can be detected normally, but any attempt to access the data area return with error. In some cases, users may avoid this problem by trial and error, such as reverse imaging to extract data, but most of the time it doesn’t work. This new feature corrects the cache problem and it works for most of these kinds of errors.
2. New feature: RAID recovery utility is appended. More details.
3. New feature: Recovery from Image File has been appended. This feature allows users to open an drive image in the program and recover data directly from the image.
4. Head Map Creation Error (Code 01) configuration limitation has been removed. Details about this limitation here.
The new version 5.00 Data Compass Package
------ Update Log for v5.00 ------Date: 2009-4-13Current Version: 5.00
1. New feature: Drive Cache Repair has been appended. Drive cache malfunction has been a typical problem for Maxtor HDD and Seagate Barracuda 7200.7 and 7200.11 HDD, which manifests itself as the following: Hard drive can be detected normally, but any attempt to access the data area return with error. In some cases, users may avoid this problem by trial and error, such as reverse imaging to extract data, but most of the time it doesn’t work. This new feature corrects the cache problem and it works for most of these kinds of errors.
2. New feature: RAID recovery utility is appended. More details.
3. New feature: Recovery from Image File has been appended. This feature allows users to open an drive image in the program and recover data directly from the image.
4. Head Map Creation Error (Code 01) configuration limitation has been removed. Details about this limitation here.
Thursday, April 2, 2009
Important Notificaiton--RAID Update for DC Users
“Upgrade my Data Compass Standard to Data Compass Premium for free” Project launched!
Dear Customers,
The new Data Compass Premium with the RAID Recovery Add-On has been released today. From now on, Data Compass will be offered to our customers in 2 different versions- Standard (without RAID recovery add-on) and Premium (with RAID recovery add-on)- in different prices.
However, to show our acknowledgment to the continued support from our customers, all Data Compass purchased before April 2nd, 2009, which is the release day of the add-on, can be upgraded from Standard to Premium free of charge, it only requires users to spend several minutes to finish a simple application.
To finish the online application, just visit the address listed below (or you can copy the entire address and paste to your browser):
http://www.salvationdata.com/mform/view.php?id=15
Instruction will be sent to you on receipt of your application to help you to finish the upgrade online.
SalvationDATA Team
Dear Customers,
The new Data Compass Premium with the RAID Recovery Add-On has been released today. From now on, Data Compass will be offered to our customers in 2 different versions- Standard (without RAID recovery add-on) and Premium (with RAID recovery add-on)- in different prices.
However, to show our acknowledgment to the continued support from our customers, all Data Compass purchased before April 2nd, 2009, which is the release day of the add-on, can be upgraded from Standard to Premium free of charge, it only requires users to spend several minutes to finish a simple application.
To finish the online application, just visit the address listed below (or you can copy the entire address and paste to your browser):
http://www.salvationdata.com/mform/view.php?id=15
Instruction will be sent to you on receipt of your application to help you to finish the upgrade online.
SalvationDATA Team
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