I mentioned this article/idea at the post-meeting activities last week. The original post is at <a href="http://blogs.zdnet.com/storage/?p=162">http://blogs.zdnet.com/storage/?p=162</a> from July 18, 2007. A nice commentary on/against it is at <a href="http://dansdata.blogsome.com/2008/10/23/death-of-raid-predicted-film-at-11/">http://dansdata.blogsome.com/2008/10/23/death-of-raid-predicted-film-at-11/</a> The basic premise is thus: The unrecoverable read error (URE) rate for SATA drives is generally documented at 10^14. About 12 TB. When we hit 2TB Drives, there's a problem. With a 7 drive RAID 5 disk failure, you're left with six 2TB drives to rebuild the replaced 'dead' drive. That's about 12 TB. So, um, that means you'll have a URE while recovering, and the recovery will shut down and tell you to restore from backups. So you go to RAID 6, which becomes the new RAID 5. :) For a while, and REQUIRED to have safety from one disk failure. That's the premise. I found the commentary AFTER the meeting, and it solved the one problem *I* had with it (that a failure rate of one in 10^14 over a sample size of 10^14 isn't 100%) that I didn't get around to quantifying with math. But, I thought i'd post it anyhow, since I offered to do so. :) Discuss among yourselves. -- Peter Smith <a href="mailto:psmith.gllug@gmail.com">psmith.gllug@gmail.com</a>