Does it seem feasible/reasonable to enable compression on ZFS root disks during JumpStart? Seems like it could buy some space & performance. -- This message posted from opensolaris.org
On Thu, Oct 16, 2008 at 12:24 AM, Vincent Fox <vincent_b_fox at yahoo.com> wrote:> Does it seem feasible/reasonable to enable compression on ZFS root disks during JumpStart?Absolutely. I did it (compression=on) on all my machines - ranged from laptop to servers. Beware, though, that on oldish CPU it can incur noticeble CPU overhead. Oh, and don''t use gzip compression - it won''t boot. -- Regards, Cyril
Vincent Fox wrote:> Does it seem feasible/reasonable to enable compression on ZFS root disks during JumpStart? > > Seems like it could buy some space & performance. >Yes. There have been several people who do this regularly. Glenn wrote a blog on how to do this when installing OpenSolaris 2008.05 http://blogs.sun.com/glagasse/entry/howto_enable_zfs_compression_when I haven''t used JumpStart in some time, but it appears as though the last arguments of the pool keyword are passed to zpool create, so you should be able to set the parameters there. Cindy? -- richard
Did you enable it in the jumpstart profile somehow? If you do it after install the OS files are not compressed. -- This message posted from opensolaris.org
Richard Elling wrote:> Vincent Fox wrote: > >> Does it seem feasible/reasonable to enable compression on ZFS root disks during JumpStart? >> >> Seems like it could buy some space & performance. >> >> > > Yes. There have been several people who do this regularly. > Glenn wrote a blog on how to do this when installing OpenSolaris 2008.05 > http://blogs.sun.com/glagasse/entry/howto_enable_zfs_compression_when > > I haven''t used JumpStart in some time, but it appears as though the last > arguments of the pool keyword are passed to zpool create, so you should > be able to set the parameters there. Cindy? >No, the last arguments are not options. Unfortunately, the syntax doesn''t provide a way to specify compression at the creation time. It should, though. Or perhaps compression should be the default. lori> -- richard > > _______________________________________________ > zfs-discuss mailing list > zfs-discuss at opensolaris.org > http://mail.opensolaris.org/mailman/listinfo/zfs-discuss >-------------- next part -------------- An HTML attachment was scrubbed... URL: <http://mail.opensolaris.org/pipermail/zfs-discuss/attachments/20081015/166c03bc/attachment.html>
> No, the last arguments are not options. > Unfortunately,<br> > the syntax doesn''t provide a way to specify > compression<br> > at the creation time. It should, though. > Or perhaps<br> > compression should be the default.<br>Should I submit an RFE somewhere then? -- This message posted from opensolaris.org
Vincent Fox wrote:>> Or perhaps compression should be the default.No way please! Things taking even more memory should never be the default. An installation switch would be nice though. Freedom of coice ;-) -- Dick Hoogendijk -- PGP/GnuPG key: F86289CE ++ http://nagual.nl/ | SunOS 10u5 05/08 ++
dick hoogendijk wrote:> Vincent Fox wrote: > >>> Or perhaps compression should be the default. > > No way please! Things taking even more memory should never be the default. > An installation switch would be nice though. > Freedom of coice ;-)Compression does not take more memory, the data is always uncompressed in the in kernel memory ARC anyway. Data on the L2ARC and ZIL devices is always uncompressed. Compression only impacts what is written to the main pool devices. Compression will use more CPU time, how much depends on which compression is choosen. Note that we already enable compression by default for most metadata (ZFS & POSIX layer) (using lzjb), the compression flag only impacts application supplied data. However I don''t think compression should be the default setting for ZFS. It may however make sense for it to be explicitly set to "on" by the OpenSolaris installer for datasets that are root/usr/opt filesystems. I don''t want to be burning CPU cycles attempting to compress most of the data I store on ZFS because most of it isn''t compressible (Audio, Video, Image files and OpenDocument files (which are in a ZIP container)). -- Darren J Moffat