Quoting "Greg Bromage" <greg@bromage.org>
Craig Sanders wrote:
one error in 10^14 bits is nothing to worry about with 500GB drives. it's starting to get worrisome with 1 and 2TB drives. It's a guaranteed error with 10+TB arrays....and even a single 3 or 4TB drive has roughly a 30-50% chance of having at least one data error.
*nod* that's the root of my concern. And the "at least one" is the issue, because once a disk fails, if there's a second error somewhere then it WILL be encountered, because the rebuild has to traverse every sector of every remaining disk.
Out of curiosity, I googled for the 10^14 bits. http://www.zdnet.com/blog/storage/how-data-gets-lost/167 Cause of data loss Perception Reality Hardware or system problem 78% 56% Human error 11% 26% Software corruption or problem 7% 9% Computer viruses 2% 4% Disaster 1-2% 1-2% I find the 26% human error interesting. IMHO a lot of IT people underestimated quite often the impact of their work and the errors they make. Sometimes a simple solution may look worse on paper but it may save the day. Because it is easy to implement and harder to break;-) For the 10^14 Bits.. that was five years ago, and I am not sure whether still valid (a Terbyte was a lot in 2007). I have overnight synchronisation of ca. 3 TeraByte per night (deltas and some full-copies after maintenance), all from mirrored disks, and haven't seen any errors over the last 18 months. ZFS scrubs did not find errors as well. Regards Peter