OpenSolaris

flag day: L2ARC and ZFS boot

Date: Tue, 13 Nov 2007 12:31:11 -0800
From: Brendan Gregg - Sun Microsystems <brendan at sun dot com>
To: onnv-gate at onnv dot eng dot sun dot com
Subject: flag day: L2ARC and ZFS boot

G'Day Folks,

The recent putback of:

PSARC 2007/618 ZFS L2ARC
6536054 second tier ("external") ARC

Is a flag day if you:

- use ZFS boot
- bfu to these new bits before 6553503 is fixed
- zpool upgrade system

The L2ARC introduced a new zpool version number (so did CIFS), and if
you are using ZFS boot and upgrade your system pool, then grub must
contend with a newer version of ZFS.  This should be fine, since bfu
should run installgrub and update grub to understand this new version.

A bug in bfu for ZFS boot systems (6553503) prevents grub from being
updated.  You end up with a server which can't boot - it gets to the grub
interface but no further.

Work around (if you haven't rebooted yet):

  After bfu'ing,
  # installgrub /boot/grub/stage1 /boot/grub/stage2 <rdsk-bootdevice>

Work around (if you did reboot, and are now unbootable):

  Net boot, and run installgrub with the images from NFS.  (I assume
  this works, but haven't tried it out yet).

You can email me if you get stuck.  This shouldn't affect many people,
since you need to be using ZFS boot in the first place, and want to upgrade
your system pool (if you don't upgrade your system pool, nothing bad
happens - you just can't add cache devices).

Brendan

~--
Brendan
[CA, USA]