Date: Tue, 16 Oct 2007 06:44:36 -0700 (PDT) From: Simun Mikecin <numisemis@yahoo.com> To: Jeremy Chadwick <koitsu@FreeBSD.org> Cc: freebsd-hackers@freebsd.org Subject: Re: Filesystem snapshots dog slow Message-ID: <5949.42099.qm@web36608.mail.mud.yahoo.com>
next in thread | raw e-mail | index | archive | help
Jeremy Chadwich wrote:
>That said, for such setups, would you recommend *not* using snapshots?
>If so, possibly we should consider removing the following code from
>src/sbin/dump/main.c:
>334 } else if (snapdump == 0) {
>335 msg("WARNING: %s\n",
>336 "should use -L when dumping live read-write "
>337 "filesystems!");
>338 } else {
Not using a snapshot for dump may produce inconsistent dump image if there was writing during
dumping. Maybe it should say something like "should use -L when dumping live read-write
filesystems for the result to be consistent (at the cost of speed)!". But that is too long :(
>> FreeBSD 7 includes ZFS. Have you thought about using it?
>I haven't. For starters, I keep seeing mails from users reporting data
>corruption or kernel panics when using it. This doesn't mean ZFS is
>"bad" (it's likely ZFS is exposing data corruption for them that's
>occuring at a lower level (controller, disk, or RAM)), but it does keep
>me from considering it a worthy alternative to UFS2 on production
>systems at this time. And then there's this:
>WARNING: ZFS is considered to be an experimental feature in FreeBSD.
>This doesn't give admins "warm fuzzies". :-) I'm considering trying ZFS
>on my home system (a ZFS filesystem atop a gstripe(8) pair), where I
>also perform nightly backups using dump, but there's a part of me which
>is asking "just how important is your data? What if ZFS breaks in the
>middle of you using dump(8) on it? What then?"
One of great things about ZFS is that you can forget about things like gstripe(8) or dump(8). You
only need two commands: zpool and zfs. ZFS is not just a filesystem, it's also a logical volume
management tool.
ZFS on FreeBSD is considered experimental since it is very new. But from experience so far with
it, only a few glitches do still exist:
1) root on ZFS is possible, but it could give you more problems then it solves (for now, it's best
to have a small, say 512MB root filesystem running UFS, but everything else on ZFS).
2) using a zvol on ZFS for swap can cause a panic
3) using ZFS on FreeBSD/i386 can cause a panic (I suggest using UFS+gjournal instead of ZFS on
FreeBSD/i386)
Personally, I would choose ZFS on FreeBSD/amd64 production machine.
____________________________________________________________________________________
Be a better Globetrotter. Get better travel answers from someone who knows. Yahoo! Answers - Check it out.
http://answers.yahoo.com/dir/?link=list&sid=396545469
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?5949.42099.qm>