RAID 6 – What You Need to Know Protect Your Data from Disaster
As you probably know RAID 5 offers you protection from a single hard disk failure. Most people would assume that RAID was the ultimate level of data protection, that level of protection would be sufficient. However in my experience if one disk in the volume has failed chances are it’s due to old degrading media and the chances of a second drive failing during the RAID rebuild are fairly high. So if your going to have a RAID array its best to have multiple stripes of parity and I still suggest you get some online backup to add that extra protection. Nothing is worse than loosing your data. Data loss is costly and extremely stressful. Hard Drive Recovery is not something most people want to deal with. Especially when think they have been protected with a RAID server and dual parity stripes
RAID 6 is similar to RAID 5 but not always in that it eliminates some of RAID 5′s major drawback of the single parity stripe by allowing you two parity stripes. Using RAID 6 you can easily sustain two simultaneous disk failures before you really need a RAID recovery service. By adding the additional parity stripe you do have the added protection but you also have additional overhead on the processor.
RAID 6 offers a second parity stripe. Two parity stripes are not always better. The reason for doing all of the calculation to enable this dual parity system is that the second parity stripe gives us an added layer of redundancy. This helps to ensure that even if the data on the failed hard disk is lost, the second parity stripe will ensure the integrity of the data on the RAID server.
If there is a second disk failure the entire rebuild process fails and you dealing with a RAID data recovery situation. With RAID 6, after the first device fails the device is running as a RAID 5, deferring but not removing the problems associated with RAID 5. When it is time to do the rebuild, all the RAID 5 choices and rebuild penalties remain. While RAID 6 adds protection, it does nothing to alleviate the performance penalty imposed during those rebuilds.