On Wed, 28 Apr 2010, Jim Horng wrote:
So on the point of not need an migration back.
Even at 144 disk. they won't be on the same raid group. So figure
out what is the best raid group size for you since zfs don't support
changing number of disk in raidz yet. I usually use the number of
the slots per shelf. or a good number is 7~10 for raidz1 and 10~20
for raidz2 or raidz3
Good luck with the 20 disks in raidz2 or raidz3.
If you are going to base the number of disks per vdev on the
shelf/rack layout then it makes more sense to base it on the number of
disk shelves/controllers than it does the number of slots per shelf.
You would want to distribute the disks in your raidz2 vdevs across the
shelves rather than devote a shelf to one raidz2 vdev. At least that
is what you would do if you care about performance and reliability.
If a shelf dies, your pool should remain alive. Likewise, there is
likely more I/O bandwidth available if the vdevs are spread across
controllers.
Bob
--
Bob Friesenhahn
bfrie...@simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer, http://www.GraphicsMagick.org/
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