zfs discuss - Oct 2007 - characterizing I/O on a per zvol basis.

Hey all -

Time for my silly question of the day, and before I bust out vi and 
dtrace...

If there a simple, existing way I can observe the read / write / IOPS on 
a per-zvol basis?

If not, is there interest in having one?

Cheers!

Nathan.

I don''t know of any way to observe IOPS per zvol and I believe
this would be tricky. Any writes/reads from individual datasets (filesystems
and zvols) will go through the pipeline and can fan out to multiple
mirrors or raidz or be striped across devices. Block writes will be
combined and pushed out in transaction groups, but if synchronous will also
have separate (and possibly multiple) intent log writes. Reads if not cached
can similarly come from multiple locations. The individual IOs are not tagged
with the dataset(s) they are servicing.

It would be easier to observe the byte count and read/write request count
for a zvol using dtrace.

Neil.


Nathan Kroenert wrote:
> Hey all -
> 
> Time for my silly question of the day, and before I bust out vi and 
> dtrace...
> 
> If there a simple, existing way I can observe the read / write / IOPS on 
> a per-zvol basis?
> 
> If not, is there interest in having one?
> 
> Cheers!
> 
> Nathan.
> _______________________________________________
> zfs-discuss mailing list
> zfs-discuss at opensolaris.org
> http://mail.opensolaris.org/mailman/listinfo/zfs-discuss

Brendan Gregg has put together a few dtrace scripts for looking at
various parts of the zfs subsystems recently.  I don''t find them in
the DTraceToolkit-0.99 release though.
  -- richard

Nathan Kroenert wrote:
> Hey all -
> 
> Time for my silly question of the day, and before I bust out vi and 
> dtrace...
> 
> If there a simple, existing way I can observe the read / write / IOPS on 
> a per-zvol basis?
> 
> If not, is there interest in having one?
> 
> Cheers!
> 
> Nathan.
> _______________________________________________
> zfs-discuss mailing list
> zfs-discuss at opensolaris.org
> http://mail.opensolaris.org/mailman/listinfo/zfs-discuss