Recovery from failed RAID systems
CnW can recover data from many RAID systems. These can be RAID 0, RAID 1 or RAID 5, either as a logical drive or as a NAS device
RAID stands for Redundant Array of Inexpensive Disks. They were developed to provide security for disk disk failure, and so with the exception of RAID 0 there is always more physical data storage than is used. The main types of RAID found on domestic, and small office systems are described below
- RAID 0 - this is not really a RAID as there is no redundancy. Data is striped between two (or more) disks generally to increase speed, and total capacity. Thus 2 x 500GB drives will give a logical 1TB drive. Any drive failure will mean 50% of all data is lost. If files are bigger than the stripe, then in effect all data will be lost
- RAID 1 - this is the simplest system. Each drive is a mirror of the other. No speed benefits, but if any single drive fails, data will be on the other drive. The danger, as with all RAID systems is if there is a power surge that destroys both drives.
- RAID 5 - this has redundant data. Typically 3-6 drives are used, and one will be used for parity. Thus, if any single drive fails, data may be recovered. Writing speed is slow as a single sector change means all other sectors on the same stripe, but a different drive has to be read, and then the data written to the correct disk, as well as the parity disk. Although it is not essential, the parity area moves between stripes
- JBOD - again not a RAID but often referred to as one. This is a Job Bunch Of Disks logically joined to make full use of all the capacity. If a drive fails, then only that sector of data is lost. It has the same advantage as RAID 0 in making full use of storage, but a failure will not cause as much data lost. However, advanced data recovery techniques may be required to process a failed JBOD as much directory information may also be ‘awol’
CnW has developed tools to recover data from RAIDs that have failed for any reason, such as a drive failure, or incorrect rebuilding after a possible drive failure. It may also be required when the hardware controller has failed. It must be noted that there are times when an automatic rebuild can do very serious damage and overwrite all instances of critical data.
The current limitations that CnW can handle are a maximum of 8 drives, and total of 2TB or storage. Please contact CnW if this does not meet your requirements - the level will be increased on a regular basis.
Specific RAID types known to CnW - though all types will be investigated
- Acer Easystore - 4 drives, Raid 5, NAS
- Lacie - RAID 1 NAS
- HP Media Vault MV2020 NAS - these have the string Broadcom NAS Version 1.1 MBR Tag in place of a conventional boot sector