In my readings i have read about lower compression than gzip and in practice
i have noticed that it is not much lower. it is something like a single
comrpession level lower so gzip -2 is more like it. I have run the beta
package for ZFS with gzip compression and the performance is much worse than
with the standard compression with a minor increase in compression level.
as far as linux ZFS with fuse. it is 'usable' but performance is not
optimized in any way. it is lacking some of the functions such as
snapshots. when is say it is not optimized, i mean it. very very slow, 1/2
the typical performance of the drives with very high CPU usage.
due to licensing differences between the kernel and ZFS, it cant be in the
kernel or linked to the kernel so i doubt we will see ZFS in linux anytime
soon.
no worries though, the *BSDs and Solaris and OSX all have support or will
support ZFS very soon.
On Nov 29, 2007 11:13 PM, Dan Pritts <[EMAIL PROTECTED]> wrote:
> On Mon, Nov 19, 2007 at 07:54:23AM -0700, dan wrote:
> > yes! i have run it in a test environment on real hardware in nexenta,
> which
> > is opensolaris meets ubuntu.
> >
> > works very well. be sure to turn on ZFS compression and turn OFF
> backuppc
> > compression. ZFS compresses much more efficiently(CPU wise) and I get
> much
> > higher transfer rates this way.
>
> My understanding is that ZFS's compression is a much lower compression
> ratio than the gzip that backuppc uses. Before I settled on this i'd
> also try gzip -1 (default -3). I think that recent opensolaris builds
> also allow zlib/gzip compression but i don't follow zfs closely enough to
> say for sure.
>
> be aware that one disadvantage of raidz vs. raid5 is that you lose some
> of raid5's random read performance. The same optimization that removes
> the raid5 write hole causes this - since you're writing one application
> write as one raid-z stripe you have to seek all the disks and read that
> whole stripe when you read the file again. Of course, it's faster on
> the relevant writes; probably what you want to optimize for.
>
> > > Has anybody tried BackupPC using a ZFS (RAIDZ) filesystem for the
> pool?
> > > It's currently a Solaris thing (and Linux?) but it's going to be in
> FreeBSD
>
> Not available in the Linux kernel. Some work has apparently been done to
> make
> it work under FUSE but I don't think it is usable yet.
>
> readonly support is in macos 10.5.0. Readwrite is supposed to arrive in a
> point release.
>
> we use ZFS in a data warehouse application and it is very good, as
> promised.
>
> danno
> --
> Dan Pritts, System Administrator
> Internet2
> office: +1-734-352-4953 | mobile: +1-734-834-7224
>
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