What To Expect With a RAID Server & Data Recovery
Common RAID Server Failures And Data Loss Issues
- RAID controller failure or configuration changed
- Two or more hard drives fail or go offline
- Server crashes and won’t remount the array or volume(s)
- Configuration becomes corrupt or damaged
- Adding incompatible hard drives
- Hardware conflicts
- Software corruption
- Virus infection, software and operating system upgrades
Recovering Data From RAID 0 Hard Drive Configurations
Because data on a RAID array or volume is typically critical to business continuity, when it becomes inaccessible due to one or more hard drives failing, a bad RAID controller, multiple hard drive failure, failed upgrade or damaged striping, RAID status in degraded mode, or errors with the MFT mount points, it is imperative that you shut the server down and get help.
Permanent data loss often occurs when hard drives are swapped, moved from one position to another or placed in other machines in an attempt to rebuild or repair the array. Formatting a boot drive or partition can also damage or remove striping, which reduces the recoverability of data and causes permanent loss.
RAID 0 Configurations
RAID Level 0 requires a minimum of 2 hard drives to implement. A RAID 0 configuration is a striped array without fault tolerance. A benefit to this RAID configuration is that it reduces the hard drives used. If any hard disk fails, the entire volume will be lost completely. For this reason, a RAID 0 configuration should never be used for any server which contains sensitive information, such as a SQL server or Exchange server.
RAID 1 Configurations
RAID Level 1 requires a minimum of 2 drives to implement. For the best performance, the controller must be able to perform two concurrent separate reads per mirrored pair or two duplicate writes per mirrored pair. In certain instances a RAID 1 array can recover from multiple and simultaneous hard drive raid controller failure, it also uses the simplest storage design. The overhead is very high at 100%, so RAID 1 may not be ideal for a larger server.
RAID 1+0 Configurations
RAID Level 10 (1+0) requires a minimum of 4 drives to implement. A RAID 10 is a striped array with segments consisting of RAID 1 arrays and having the same fault tolerance as RAID level 1 plus the overhead fault-tolerance of mirroring. In certain instances a RAID 10 array can recover from multiple and simultaneous hard drive failure. Because of limited scalability and high inherent costs, RAID 1+0 is typically used in database server applications like an Exchange Server or SQL database server which requires high performance and high fault tolerance levels.
RAID 0+1 Configurations
RAID Level 0+1 (0+1) requires a minimum of 4 drives to implement. A RAID 0+1 is a striped array with segments consisting of RAID 0+1 arrays and having the same fault tolerance as RAID level 0+1 plus the overhead fault-tolerance of mirroring. In certain instances a RAID 0+1 array can recover from multiple and simultaneous hard drive failure, however, a single drive failure will cause it to run as RAID 0. Because of limited scalability and high inherent costs, RAID 0+1 is typically used in imaging applications general file servers. It tends to be a high performance solution with reduced emphasis on reliability.