If RAID dies, will the storage array crumble?

I stumbled upon an article in SearchStorage Asia about a month ago which titled "RAID should die" and it continues to bug me. The author, Mr. Allan Tan, is right. RAID haven't changed much for more 20 years ago and RAID technology remained the cornerstone of almost every storage array.

However, as the author has argued, RAID was useful for the disk capacities of yesteryears. I remembered that the first storage array I worked on was Sun's external storage box. The SS1000 was a bunch of 64MB disks in some RAID configuration using either Veritas Volume Manager or Sun's own Solstice DiskSuite. Then I went on to work the NetApp F700 series which sported the 9GB disks.

Yes, RAID was the best thing of the storage array and it is still very relevant today. However, the disk capacities of today are 2TB with bigger capacities in the near future. Can RAID cope? If a 1TB disk failed in a RAID 5+1 configuration, the RAID reconstruction could take 1/2 a day or more. With the larger disk capacities looming, the reconstruction process could take more than a day. Given the high demands of the best data availability, RAID 6 with dual parity was supposed to give some breathing space.

I found this table on the Internet, courtesy of Enterprise Storage Forum. Very interesting indeed.



Today, Sun's (sorry, it should be Oracle now) ZFS offers triple parity protection in RAID Z3. Pretty soon, it may no longer become viable to use RAID. But for now, RAID seems like the only thing we got.

What's next after RAID? As communication channels become speedier, there are many other possible successors to RAID. I have been reading about Forward Error Correction, Reed Solomon Erasure Encoding, LDPC and Hamming ECC. These newer approaches seem to be good candidates to supercede RAID. Food for thoughts.

We cannot predict what's going to happen to RAID. We know that there are times that better and greater technologies may not see the light of day, and with almost all storage arrays tightly connected to RAID, we may see RAID for a long time. Long Live RAID!