There’s been lots of talk about RAID 6 as it compares to RAID 5 and the reliability benefits that are gained by SATA drives when using RAID 6 – so I’ve decided NOT to talk about that anymore!

Instead I thought I’d discuss two other RAID levels out there and available to folks. RAID 5EE and RAID 1E.

RAID 5EE takes traditional RAID and actually incorporates the hot spare into the RAID set. It doesn’t give any additional capacity adding that drive, but it does something quite unique. 5EE actually stripes the hot spare capacity across all of the disks in the RAID set. This effectively allows you to have your spare drive out “getting some exercise” serving up bits instead of sitting idly by waiting for one of his brothers to keel over. Ever wondered if your hot spare would actually jump in and take on the burden of a failed drive? How do you know if your hot spare is any good? Well, RAID 5EE makes sure that doesn’t happen! Now, if you do have a failure, you still have a parity rebuild process to wait on before you can sustain another failure. (Different than the more talked about RAID level that I’m not talking about right now - where you can actually sustain two simultaneous drive failures) It’s also important to note that this hot spare capacity can not be used “globally” for other RAID sets that may have a failure. That extra drive becomes dedicated to the RAID set it’s associated with.

RAID 1E is a very unique combination of RAID 0 and RAID 1. It requires at least 3 drives. The main advantage is that you can have an odd number of disks basically “mirrored”. Like traditional RAID 1, the amount of usable capacity is exactly 50% of the total capacity of all disks, no matter how many disks are in the array. If you don’t have an odd number of disks that need the RAID 1 performance characteristics, then it’s recommended to use RAID 10 instead. RAID 10 has fewer combinations for a failed drive.

For more information on all the RAID levels out there, check out the white paper on Adaptec’s site titled, “Which RAID Level is Right for Me?”

Blog ya later!

Joe

This entry was posted on Thursday, November 3rd, 2005 and is filed under General, Storage Interconnects & RAID, Advisor - Joe. You can follow any responses to this entry through the RSS 2.0 feed. You can skip to the end and leave a response. Pinging is currently not allowed.