Choosing a RAID level can be difficult, particularly for systems with high fault tolerance needs. Many businesses choose nested RAID levels in order to prevent potential data loss and downtime, but while many nested RAID options can improve system reliability, no RAID option provides perfect protection against data loss.
Two of the most popular high-tolerance nested RAID levels are RAID 1+0 and 5+0 (also known as RAID 10 and RAID 50). For many system administrators, these are extremely effective options, but keeping data on a single physical system is always a risky proposition.
RAID 10 Systems and Data Loss
RAID 10 stripes a mirrored set of drives to keep some of the advantages of RAID 0 while preventing a single hard drive failure from causing data loss. This type of system has excellent read performance and somewhat limited write performance.
While the technology fell somewhat out of favor over the past decade, RAID 10 is making a comeback thanks to high-speed SSD drives that cut down on write times. RAID 10 offers excellent reliability, but there is no guarantee that striping is completely accurate. Data corruption is a potentially serious problem, and failed hard drives need to be replaced quickly in order to prevent losses.
RAID 50 Systems and Data Loss
RAID 50 systems are essentially a RAID 0 array striped across a series of drives to create a RAID 5. Users benefit from high transfer speeds and excellent fault tolerance, provided that the system is properly maintained. Unfortunately, there is still a potential for data loss in this type of system.
If a RAID 50 hard drive fails and is not immediately replaced, the corresponding drives in its set could potentially fail, resulting in data loss. Most RAID 50 systems include a hot spare to prevent this type of occurrence, but data loss is always a possibility during rebuild procedures.
There is some evidence to suggest that all RAID devices have a higher-than-average chance of failure during rebuilds due to the relatively large amount of stress that the rebuild places on the RAID hard drives. We regularly receive RAID arrays that failed entirely during rebuilds. In some cases, RAID rebuilds failed due to hardware or software issues unrelated to the health of the RAID hard disk drives, but the result is always the same: serious data loss and potential downtime.
Avoiding Data Loss on Nested RAID Systems
Any server can fail, and in order to avoid data loss, administrators should always recognize this possibility. Regular system backups are the only way to completely prevent any possibility of file loss.
With that being said, nested RAID levels do provide improved performance and better reliability for certain applications. RAID 10 is common for NAS devices, while RAID 50 systems are common for enterprise-level systems. For the best results, administrators should check hot spares regularly to ensure that hard drive failures are immediately treated.
If data loss occurs on your nested RAID, keep the hard drives organized and labeled. Do not attempt a rebuild after a failed rebuild, as this can seriously affect the data recovery process. Never attempt to repair member hard drives and never run recovery software.
RAID 50, RAID 10 and other nested RAID devices have a high chance of successful recovery when treated in an appropriate environment. Secure Data Recovery Services offers free media evaluations for all storage devices, and we can provide price quotes for all nested RAID systems. For more information or to set up an evaluation, call 1-800-388-1266.