zpool add log to root pool

[Charles Sprickman]

On Sep 17, 2012, at 8:34 AM, Olivier Smedts wrote:

> Hello ZFS folks,
> 
> Is there anyone here using a separate log device (or "ZIL") on a root pool ?
> 
> # zpool add tank log gpt/zil
> cannot add to 'tank': root pool can not have multiple vdevs or separate logs
> 
> Under 9-STABLE, using zpool v28. This seems to be a limitation from
> OpenSolaris. For example, FreeBSD supports booting from a
> multiple-vdev root pool. I found that most people use the "unset
> bootfs property, add vdev, set bootfs again" trick to have a working
> multiple-vdev root pool under FreeBSD.

I did that and it seems to work.

  pool: zroot
 state: ONLINE
  scan: scrub repaired 0 in 0h0m with 0 errors on Tue Aug 21 01:28:27 2012
config:

	NAME           STATE     READ WRITE CKSUM
	zroot          ONLINE       0     0     0
	  mirror-0     ONLINE       0     0     0
	    ada1p3     ONLINE       0     0     0
	    ada2p3     ONLINE       0     0     0
	  mirror-1     ONLINE       0     0     0
	    ada3p3     ONLINE       0     0     0
	    ada0p3     ONLINE       0     0     0
	logs
	  mirror-2     ONLINE       0     0     0
	    gpt/zil-a  ONLINE       0     0     0
	    gpt/zil-b  ONLINE       0     0     0
	cache
	  gpt/l2arc-a  ONLINE       0     0     0
	  gpt/l2arc-b  ONLINE       0     0     0

errors: No known data errors

Lost my /dev/gpt entries for the existing mirror slices in the process though...

> I think I can do the same for
> the log device but don't want to loose my data.
> 
> Is there anyone successfuly using a log device / zil on a root pool
> under FreeBSD ?

Mine works, but I've never been able to find any official confirmation from the -fs folks as to how "proper" or supported the configuration is.  Not too many other options on 1U boxes though really...

Charles



> Thanks
> 
> -- 
> Olivier Smedts                                                 _
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