> From: zfs-discuss-boun...@opensolaris.org [mailto:zfs-discuss- > boun...@opensolaris.org] On Behalf Of Bryan Horstmann-Allen > > The ability to remove the slogs isn't really the win here, it's import > -F. The
Disagree. Although I agree the -F is important and good, I think the log device removal is the main win. Prior to log device removal, if you lose your slog, then you lose your whole pool, and probably your system halts (or does something equally bad, which isn't strictly halting). Therefore you want your slog to be as redundant as the rest of your pool. With log device removal, if you lose a slog while the system is up, worst case is performance degradation. With log device removal, there's only one thing you have to worry about: Your slog goes bad, and undetected. So the system keeps writing to it, unaware that it will never be able to read, and therefore when you get a system crash, and for the first time your system tries to read that device, you lose information. Not your whole pool. You lose up to 30 sec of writes that the system thought it wrote, but never did. You require the -F to import. Historically, people always recommend mirroring your log device, even with log device removal, to protect against the above situation. But in a recent conversation including Neil, it seems there might be a bug which causes the log device mirror to be ignored during import, thus rendering the mirror useless in the above situation. Neil, or anyone, is there any confirmation or development on that bug? Given all of this, I would say it's recommended to forget about mirroring log devices for now. In the past, the recommendation was "Yes mirror." Right now, it's "No don't mirror," and after the bug is fixed, the recommendation will again become "Yes, mirror." _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
