On 07/10/12 09:25 PM, Jordi Espasa Clofent wrote:
Hi all,

By default I'm using ZFS for all the zones:

admjoresp@cyd-caszonesrv-15:~$ zfs list
NAME                         USED  AVAIL  REFER  MOUNTPOINT
opt                         4.77G  45.9G   285M  /opt
opt/zones                   4.49G  45.9G    29K  /opt/zones
opt/zones/glad-gm02-ftcl01   367M  45.9G   367M  /opt/zones/glad-gm02-ftcl01
opt/zones/glad-gp02-ftcl01   502M  45.9G   502M  /opt/zones/glad-gp02-ftcl01
opt/zones/glad-gp02-ftcl02  1.21G  45.9G  1.21G  /opt/zones/glad-gp02-ftcl02
opt/zones/mbd-tcasino-02     257M  45.9G   257M  /opt/zones/mbd-tcasino-02
opt/zones/mbd-tcasino-04     281M  45.9G   281M  /opt/zones/mbd-tcasino-04
opt/zones/mbfd-gp02-ftcl01   501M  45.9G   501M  /opt/zones/mbfd-gp02-ftcl01
opt/zones/mbfd-gp02-ftcl02   475M  45.9G   475M  /opt/zones/mbfd-gp02-ftcl02
opt/zones/mbhd-gp02-ftcl01   475M  45.9G   475M  /opt/zones/mbhd-gp02-ftcl01
opt/zones/mbhd-gp02-ftcl02   507M  45.9G   507M  /opt/zones/mbhd-gp02-ftcl02

However, I have the compression disabled in all of them.

According to this Oracle whitepaper

"The next example demonstrates the compression property. If compression
is enabled, Oracle Solaris ZFS will transparently compress all of the
data before it is written to disk. The benefits of compression
are both saved disk space and possible write speed improvements."

What exactly means "POSSIBLE" write speed improvements?

With compression enabled, less data has to be written to disk, so N bytes writes in N/compress ratio time.

On most systems, the performance cost of compressing and uncompressing data is relatively low.
As you can see above I don't use to have any room problems, so if I'm
going to enable the compression flag it has to be because of the write
speed improvements.

I always enable compression by default and only turn it off for filesystems I know hold un-compressible data such as media files.


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