[mythtv-users] ZFS anyone? Need to move off ZFS Myth machine and not sure what to do..

Torfinn Ingolfsen tingox at gmail.com
Fri Oct 14 07:19:37 UTC 2011

On Thu, Oct 13, 2011 at 10:45 PM, Mark <markhsa at gmail.com> wrote:
> On Thu, 2011-10-13 at 16:43 -0400, Brian J. Murrell wrote:
>> On 11-10-13 04:30 PM, Mark wrote:
>> >
>> > The existing ZFS is spanned across 5 2TB drives.  I could simply plug
>> > them in on a new machine if ZFS were supported.
>> > Right now, Myth on Fedora, all storage is NFS to a FreeNAS box that has
>> > the 5 drives.  I need to move that storage local to the Myth box.
>> >
>> > Trying to avoid a big data move and buying drives to move into as I cant
>> > destroy the FreeNAS-ZFS system until the data is gone.
>> You'd need at most 1 new 2TB drive and that's assuming your 5x2TB ZFS
>> filesystem is more than 80% full.  If you can get it down to 80% or
>> less, you shouldn't even need any new drives since...
>> Surely one of ZFS' fancy-pants features is that it lets you remove a
>> drive from a filesystem without a loss of data -- assuming there is at
>> least as much space free as the size of that disk you want to remove.
>> If you can remove a drive (again, assuming you have the space free to do
>> it) you remove it (if not, this is where you will need the one new 2TB
>> drive), move it to your myth box, create an ext4 filesystem on it, put
>> it into a storage group and then move 2TB of recording off of ZFS on
>> that disk.
>> Doing so will free up another 2TB of disk on your ZFS filesystem
>> allowing you to remove a second drive.  Move it to your myth box, put
>> ext4 on it and move another 2TB from your ZFS filesystem.  Rinse and
>> repeat until you have all of your drives independent and in a storage
>> group.  If you had to buy a new 2TB drive to accomplish it, you probably
>> needed it anyway.  :-)
> Great idea!
> I did not think of moving it in a staged approach like that.
> Thanks for the input.  That is likely exactly what I will do.

Before doing that, tell us how your ZFS pool layout is. Use the 'zpool
status' command for example.
Depending on your pool configuration, you won't be able to free all
your drives from the pool with the suggested approach.
Any redundant pool has a minimum number of drives; if you go below
that your pool isn't complete any more.
Torfinn Ingolfsen

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