Thanks for forwarding this thread. It really explains the failure modes quite well. I stand corrected. -nld
On Fri, May 9, 2014 at 8:36 AM, Chris Ferebee <[email protected]> wrote: > > If you crash, reset or lose power, ZFS can replay the ZIL from the slog > device, because it has battery/supercap etc. power-loss protection and is > therefore persistent. > > If the slog device dies, all the data in the ZIL is still cached in RAM > and can be written out from there. ZFS automatically switches the ZIL from > the slog to the main pool. > > If the slog device dies at the same instant you lose power, you just > suffered a drone strike and all bets are off. > > Check this thread, which has some excellent comments from Richard Elling > and others: > > < > http://openindiana.org/pipermail/openindiana-discuss/2012-June/008249.html > > > > Richard also points out that we are saying ZIL when we mean slog. I stand > corrected. > > Best, > Chris > > > Am 09.05.2014 um 13:34 schrieb Narayan Desai via smartos-discuss < > [email protected]>: > > > On Fri, May 9, 2014 at 3:15 AM, Chris Ferebee via smartos-discuss < > [email protected]> wrote: > > > > Therefore, write-endurance and power-loss protection are essential for a > ZIL device. OTOH, if the ZIL fails, the system should keep running, just > with reduced sync write performance. So you only need to mirror the ZIL if > you can’t tolerate a drop in performance for the time it takes to provision > a new ZIL device. > > > > Won't you lose data if you lose a ZIL? Presumably everything stored on > it at failure time would be lost, right? > > > > I also vaguely recall that we've had problems with pools where the ZIL > has failed, but I'm sure that someone on this list could definitively say > one way or the other. > > -nld > > ------------------------------------------- smartos-discuss Archives: https://www.listbox.com/member/archive/184463/=now RSS Feed: https://www.listbox.com/member/archive/rss/184463/25769125-55cfbc00 Modify Your Subscription: https://www.listbox.com/member/?member_id=25769125&id_secret=25769125-7688e9fb Powered by Listbox: http://www.listbox.com
