Date: Tue, 23 Nov 2010 22:02:30 +0000 From: krad <kraduk@gmail.com> To: Kurt Lidl <lidl@pix.net> Cc: freebsd-hackers@freebsd.org, Chris St Denis <chris@smartt.com> Subject: Re: UFS Snapshots and iowait Message-ID: <AANLkTin7mSuQXUc==7CD=BvAPHK4J4d5gmPbmtPe-Bq0@mail.gmail.com> In-Reply-To: <20101123194950.GB74848@pix.net> References: <4CEC0A27.8080900@smartt.com> <20101123194950.GB74848@pix.net>
next in thread | previous in thread | raw e-mail | index | archive | help
On 23 November 2010 19:49, Kurt Lidl <lidl@pix.net> wrote: > On Tue, Nov 23, 2010 at 10:38:31AM -0800, Chris St Denis wrote: > > Is this just due to the very high io bandwidth usage associated with > > making a snapshot, or does the creation of this snapshot completely > > block IO writes for around 5 minutes? > > It blocks updates to the filesystem while during part of the > snapshot process. > > See the comments in /usr/src/sys/ufs/ffs/ffs_snapshot.c > > I found using UFS snapshots on a production fileserver untenable > during normal working hours. I have a backup fileserver that I > rsync the files to, and then use the UFS snapshots there. > > > Any suggested workarounds? I already bumped up the number of Apache > > slots to 166% but it looks like I would have to increase the number much > > more to use that as a primary solution. > > Use ZFS. The way snapshots work there, they are nearly instantanous > to create, and you are not limited to 20 snapshots per filesystem. > > -Kurt > _______________________________________________ > freebsd-hackers@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-hackers > To unsubscribe, send any mail to "freebsd-hackers-unsubscribe@freebsd.org" > I can testify zfs snapshots are very usable, as we use it to backup our mysql and oracle databases. Issue a write lock, flush, snap, remove lock, backup snapshot All takes a few seconds and is fairly seamless
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?AANLkTin7mSuQXUc==7CD=BvAPHK4J4d5gmPbmtPe-Bq0>