zfs discuss - Oct 2010 - Online zpool expansion feature in Solaris 10 9/10

I?m testing the new online zpool expansion feature of Solaris 10 9/10.  My zpool
was created using the entire disk (ie. no slice number was used).  When I resize
my LUN on our SAN (an HP-EVA4400) the EFI label does not change.

On the zpool, I have autoexpand=on, and I?ve tried using zpool online ?e.  But
of course, unless the EFI label gets updated in response to the LUN size change,
the higher layers (zpool, zfs) will see no change.

Bug ID 6475340 (?ZFS needs to write a new EFI label describing the new size,
before it can use the new space)? was meant to fix this ? and a fix was
delivered in the 09/10 kernel patch 142909-17 which I?m running.

Is the design of these changes such that it?s meant to automatically update the
EFI label?
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Hi James,

I''m looking into this and will get back to you shortly.

Thanks,

Cindy

On 10/13/10 00:14, James Patterson wrote:
> I?m testing the new online zpool expansion feature of Solaris 10 9/10.  My
zpool was created using the entire disk (ie. no slice number was used).  When I
resize my LUN on our SAN (an HP-EVA4400) the EFI label does not change.
> 
> On the zpool, I have autoexpand=on, and I?ve tried using zpool online ?e. 
But of course, unless the EFI label gets updated in response to the LUN size
change, the higher layers (zpool, zfs) will see no change.
> 
> Bug ID 6475340 (?ZFS needs to write a new EFI label describing the new
size, before it can use the new space)? was meant to fix this ? and a fix was
delivered in the 09/10 kernel patch 142909-17 which I?m running.
> 
> Is the design of these changes such that it?s meant to automatically update
the EFI label?

An update to this query.  Cindy did look into this for me, and found that:

[i]I have confirmation that although the ZFS autoexpand property and supporting
bugs like 475340 are in the Solaris 10 9/10 release, the supporting sd driver
work to update the EFI label is not.
In previous Solaris 10 releases, you could workaround the LUN expansion problem
by either export/importing the pool or rebooting the system. My sense is that
the integration of the autoexpand property is now restricting this workaround.
We are considering how to resolve this but it might take some time.[/i]

So, at the end of the day I can make the LUN larger via my SAN managment
interface, but the sd driver is unaware of this change so the EFI label never
gets updated, meaning format continues to show the old size. I realise there are
tricks with labelling under the format command using autoconfigure, but we
wanted to avoid that non supported method.

Also, as Cindy mentions, a zpool export/import fails to udpate the EFI label. 
Apparently this has worked in the past, although I''d never tried this.

As a result, the best method to extend a zpool in our case is to create a second
larger LUN and add it to the zpool to create a mirror, then detach the old
smaller device.  Then run zpool online -e to actually expand the zpool.

James.
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