> From: zfs-discuss-boun...@opensolaris.org [mailto:zfs-discuss-
> boun...@opensolaris.org] On Behalf Of Bob Friesenhahn
> Zfs is all about caching so the cache really does need to be included
> (and not intentionally broken) in any realistic measurement of how the
> system will behave.

I agree with what others have said - and this comment in particular.

The only useful thing you can do is to NOT break your system intentionally,
and instead find ways to emulate the real life jobs you want to do.  This is
exceptionally difficult, because in real life, your system will be on for a
long time, doing periodic snapshot rotation, and periodic scrubs, and people
will be doing all sorts of work scattered about on disk...  Sometimes
writing, sometimes reading, sometimes modifying, sometimes deleting.

The modifies and deletes are particularly important.  Because when you mix a
bunch of reads/writes/overwrites/deletes in with a bunch of snapshots
automatically being created & destroyed over time, these behaviors totally
change the way data gets distributed throughout your pool.  And the periodic
scrub will also affect your memory usage and therefore distribution

Given the amount of ram you have, I really don't think you'll be able to get
any useful metric out of iozone in this lifetime.

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