Hello ZFS forum, I''m curious about ZFS and read a bit about it, though still have a few open questions. I''d like to have both ... - a pooling of harddisk space (like LVM in Linux) and - integrated data redundancy & possibly speedups (something like RAID-5) RAID-Z seems to provide that, if I''m correct? With RAID-Z ... 1) is it possible to use differently-sized disks in raidz? They''re often the same brand, speed, type and generation, just different sizes. 2) is it possible to easily add (-> more available space) and remove (as to replace them) disks to/from a RAID-Z device (if that''s the right term)? Thanks for your time and clarifications, Ernst Rohlicek This message posted from opensolaris.org
Hello Ernst,
Tuesday, June 20, 2006, 12:32:55 AM, you wrote:
ERj> Hello ZFS forum,
ERj> I''m curious about ZFS and read a bit about it, though still
have a few open questions.
ERj> I''d like to have both ...
ERj> - a pooling of harddisk space (like LVM in Linux) and
ERj> - integrated data redundancy & possibly speedups (something like
RAID-5)
ERj> RAID-Z seems to provide that, if I''m correct?
yes.
ERj> With RAID-Z ...
ERj> 1) is it possible to use differently-sized disks in raidz?
ERj> They''re often the same brand, speed, type and generation, just
different sizes.
Yes, you can but maximum common size of all disks in one raidz group
will be used. You could however group disks with equal sizes in raidz
groups and stripe between them in one pool.
ERj> 2) is it possible to easily add (-> more available space) and
ERj> remove (as to replace them) disks to/from a RAID-Z device (if
that''s the right term)?
you can add disks to a raidz pool but it won''t actually grow stripe
width and in order to preserver redundancy you will have to add at
least pairs of disks.
You can''t remove a disk from a pool (except submirrors) - at least
yet.
Additionally to raid-z (aka raid-5) you can use raidz2 (aka raid-6),
mirroring (raid-1), striping (raid-0) and a combination of striping
and mirroring or raidz.
--
Best regards,
Robert mailto:rmilkowski at task.gda.pl
http://milek.blogspot.com
ERj> 2) is it possible to easily add (-> more available space) and > you can add disks to a raidz pool but it won''t actually grow stripe > width and in order to preserver redundancy you will have to add at > least pairs of disks. if one is drive bay limited, replace *all* the raidz drives, one at a time... root at nas2[7:26pm]/tmp % mkfile 100m 1 2 3 root at nas2[7:26pm]/tmp % zpool create t raidz2 /tmp/1 /tmp/2 /tmp/3 root at nas2[7:26pm]/tmp % zfs list t NAME USED AVAIL REFER MOUNTPOINT t 57.9K 158M 2.00K /t root at nas2[7:26pm]/tmp % zpool offline t /tmp/1 Bringing device /tmp/1 offline root at nas2[7:26pm]/tmp % mkfile 200m 1 root at nas2[7:27pm]/tmp % zpool replace t /tmp/1 root at nas2[7:27pm]/tmp % zpool offline /tmp/2 Bringing device /tmp/2 offline root at nas2[7:27pm]/tmp % mkfile 200m 2 root at nas2[7:27pm]/tmp % zpool replace t /tmp/2 root at nas2[7:27pm]/tmp % zpool offline t /tmp/3 Bringing device /tmp/3 offline root at nas2[7:27pm]/tmp % mkfile 200m 3 root at nas2[7:27pm]/tmp % zpool replace t /tmp/3 root at nas2[7:27pm]/tmp % zfs list t NAME USED AVAIL REFER MOUNTPOINT t 92.6K 358M 32.6K /t root at nas2[7:27pm]/tmp % zpool destroy t works with raidz2 (two parity disks) too. Rob