Increasing ZFS Disk Sizes

[Matthew Seaman]

On 24/04/2012 04:22, Tim Gustafson wrote:
> Am I missing anything here, or is the this "safe" way to do this?  Do
> I need to do anything special (other than the gpart bootcode command)
> to make the new disk bootable?  Do I need to do anything special to
> set up the swap partition?  Right now, I have this in my /etc/fstab:

Yes, this is a good way to do this change.  The only better way would be
to add the 2TB disk to the mirror first -- thus making a three way
mirror, let that resilver, and then remove one of the old drives.  But
that requires you to have available spare disk slots.

> /dev/gptid/47bc37af-873b-11e1-b913-003048b98c9e none swap sw 0 0
> 
> Would it be safe to change that to:
> 
> /dev/ada1p2 none swap sw 0 0
> 
> during the operation, and then back to ada0p2 when the re-silvering is complete?

What does swapinfo(8) say?  If your system is swapping directly to the
partitions on both those drives then you have some work to do.  You
can't just pull a drive with an active swap area on it -- you should use
swapoff(8) to disable the swap area first.  That's something that can
take some time, lots of IO and is not actually guaranteed to work; in
which case you may need to edit /etc/fstab and reboot to free up that
swap area.

One thing I'd certainly recommend your doing here is to set up a gmirror
across your swap partitions.  As it is, despite having your filesystems
mirrored using ZFS, you are still vulnerable to system crash should one
of your drives fail.  To do that:

Halt the system and reboot into single user mode (ie shutdown -r).  You
want this so that your current swap partitions are not enabled, as
you'll need to modify their configuration.  Add --

   geom_mirror_load="YES"

to /boot/loader.conf  One time only, run 'kldload geom_mirror' for the
initial setup -- in future this will happen automatically.

Create the mirrored swap by:

   # gmirror label -b load -F swap /dev/gpt/swap0 /dev/gpt/swap1

and then modify /etc/fstab so that the swap related line is like so:

   /dev/mirror/swap none            swap    sw      0       0

Then hit ^D to carry on booting as normal.

	Cheers,

	Matthew

-- 
Dr Matthew J Seaman MA, D.Phil.                   7 Priory Courtyard
                                                  Flat 3
PGP: http://www.infracaninophile.co.uk/pgpkey     Ramsgate
JID: matthew at infracaninophile.co.uk               Kent, CT11 9PW

-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 267 bytes
Desc: OpenPGP digital signature
Url : http://lists.freebsd.org/pipermail/freebsd-fs/attachments/20120424/891abfb8/signature.pgp