[zfs-discuss] One dataset per user?

Bob Friesenhahn
2010-06-21T15:40:03Z

On Mon, 21 Jun 2010, Arne Jansen wrote:
>
> Especially if the characteristics are different I find it a good
> idea to mix all on one set of spindles. This way you have lots of
> spindles for fast access and lots of space for the sake of space. If
> you devide the available spindles in two sets you will have much
> fewer spindles available for the responsiveness goal. I don''t
think
> taking them into a mirror can compensate that.

This is something that I can agree with.  Total vdevs in the pool is
what primarily determines its responsiveness.  while using the same
number of devices, splitting the pool might not result in more vdevs
in either pool.  Mirrors do double the amount of readable devices but
the side selected to read is random so the actual read performance
improvement is perhaps on the order of 50% rather than 100%.  Raidz
does steal IOPS so smaller raidz vdevs will help and result in more
vdevs in the pool.

Bob
--
Bob Friesenhahn
bfriesen at simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/