Frank Middleton
Sun, 19 Jul 2009 14:33:17 -0700
On 07/19/09 05:00 AM, dick hoogendijk wrote:
(i.e. non ECC memory should work fine!) / mirroring is a -must- !
Yes, mirroring is a must, although it doesn't help much if you have memory errors (see several other threads on this topic): http://en.wikipedia.org/wiki/Dynamic_random_access_memory#Errors_and_error_correction"Tests[ecc]give widely varying error rates, but about 10^-12
error/bit·h is typical, roughly one bit error, per month, per gigabyte of memory." That's roughly 1 per week in 4GB. If 1 error in 50 results in a ZFS hit, that's one/year per user on average. Some get more, some get less.That sounds like pretty bad odds... "In most computers used for serious scientific or financial computing and as servers, ECC is the rule rather than the exception, as can be seen by examining manufacturers' specifications." Sun doesn't even sell machines without ECC. There's a reason for that. IMO you'd be nuts to run ZFS on a machine without ECC unless you don't care about losing some or all of the data. Having said that, we have yet to lose an entire pool - this is pretty hard to do! I should add that since setting copies=2 and forcing the files to be copied, there have been no more unrecoverable errors on a particularly low end machine that was plagued with them even with mirrors (and a UPS with a bad battery :-) ).On 19-Jul-09, at 7:12 AM, Russel wrote:
As this was not clear to me. I use VB like others use vmware etc to run solaris because its the ONLY way I can,
Given that PC hardware is so cheap these days (used SPARCS even cheaper), surely it makes far more sense to build a nice robust OSOL/ZFS based file server *with* ECC. Then you can use iscsi for your VirtualBox VMs and solve all kinds of interesting problems. But you still need to do backups. My solution for that is to replicate the server and backup to it using zfs send/recv. If a disk fails, you switch to the backup and no worries about the second disk of the mirror failing during a resilver. A small price to pay for peace of mind. _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss