Hi Albert,

On Sat, Dec 1, 2012 at 4:20 AM, Albert Shih <albert.s...@obspm.fr> wrote:
>  Le 30/11/2012 ? 15:52:09+0100, Tomas Forsman a écrit
>> On 30 November, 2012 - Albert Shih sent me these 0,8K bytes:
>> > I would like to knwon if with ZFS it's possible to do something like that :
>> >
>> >     http://tldp.org/HOWTO/LVM-HOWTO/removeadisk.html

The commands described on that page do not have direct equivalents in
zfs. There is currently no way to reduce the number of "top-level
vdevs" in a pool or to change the RAID level.

>> > I have a zpool with 48 disks with 4 raidz2 (12 disk). Inside those 48 disk
>> > I've 36x 3T and 12 x 2T.
>> > Can I buy new 12x4 To disk put in the server, add in the zpool, ask zpool
>> > to migrate all data on those 12 old disk on the new and remove those old
>> > disk ?

In your specific example this means that you have 4 * RAIDZ2 of 12
disks each. Zfs doesn't allow you to reduce that there are 4. Zfs
doesn't allow you to change any of them from RAIDZ2 to any other
configuration (eg RAIDZ). Zfs doesn't allow you to change the fact
that you have 12 disks in a vdev.

>> You pull out one 2T, put in a 4T, wait for resilver (possibly tell it to
>> replace, if you don't have autoreplace on)
>> Repeat until done.

If you don't have a full set of new disks on a new system, or enough
room on backup tapes to do a backup-restore, there are only two ways
for to add capacity to the pool:
1) add a 5th top-level vdev (eg. another set of 12 disks)
2) replace the disks with larger ones one-by-one, waiting for a
resilver in between

> When I would like to change the disk, I also would like change the disk
> enclosure, I don't want to use the old one.

You didn't give much detail about the enclosure (how it's connected,
how many disk bays it has, how it's used etc.), but are you able to
power off the system and transfer the all the disks at once?

> And what happen if I have 24, 36 disks to change ? It's take mounth to do
> that.

Those are the current limitations of zfs. Yes, with 12x2TB of data to
copy it could take about a month.

If you are feeling particularly risky and have backups elsewhere, you
could swap two drives at once, but then you lose all your data if one
of the remaining 10 drives in the vdev failed.

zfs-discuss mailing list

Reply via email to