On 7 apr 2010, at 14.28, Edward Ned Harvey wrote: >> From: zfs-discuss-boun...@opensolaris.org [mailto:zfs-discuss- >> boun...@opensolaris.org] On Behalf Of Jeroen Roodhart >> >>> If you're running solaris proper, you better mirror >>> your >>>> ZIL log device. >> ... >>> I plan to get to test this as well, won't be until >>> late next week though. >> >> Running OSOL nv130. Power off the machine, removed the F20 and power >> back on. Machines boots OK and comes up "normally" [...] >> >> Nice! Running a later version of ZFS seems to lessen the need for ZIL- >> mirroring... > > Yes, since zpool 19, which is not available in any version of solaris yet, > and is not available in osol 2009.06 unless you update to "developer > builds," Since zpool 19, you have the ability to "zpool remove" log > devices. And if a log device fails during operation, the system is supposed > to fall back and just start using ZIL blocks from the main pool instead. > > So the recommendation for zpool <19 would be *strongly* recommended. Mirror > your log device if you care about using your pool. > And the recommendation for zpool >=19 would be ... don't mirror your log > device. If you have more than one, just add them both unmirrored.
Rather: ... >=19 would be ... if you don't mind loosing data written the ~30 seconds before the crash, you don't have to mirror your log device. For a file server, mail server, etc etc, where things are stored and supposed to be available later, you almost certainly want redundancy on your slog too. (There may be file servers where this doesn't apply, but they are special cases that should not be mentioned in the general documentation.) > I edited the ZFS Best Practices yesterday to reflect these changes. I'd say, that "In zpool version 19 or greater, it is recommended not to mirror log devices." is not a very good advice and should be changed. /ragge _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
