Drive labelling with ZFS

David Christensen dpchrist at
Tue Jun 13 23:32:58 UTC 2017

On 06/13/2017 02:52 PM, Frank Leonhardt wrote:
> Can anyone help me? I'm going quietly crazy here with FreeBSD 11-RELEASE
> If you're creating a non-trivial ZFS raidz zpool, I've heard it said
> that labelling the GPT partitioned drives with their shelf and row
> number is A Good Thing. (I'm not talking about sticky labels stuck on
> the drive, but they're good too). When you look at a healthy zpool
> status you get a list of all the GEOMs, but when one fails it's
> identified by the GUID and not the device. Good luck tracking it down
> from that piece of information, unless it's also making a strange
> buzzing noise.
> So I though I'd just use use glabel label to set a label on the vdev
> (e.g "/dev/da7p3") and zpool would use that instead. Nope; only the
> GUID. I also, naively, thought that setting the label would cause it to
> appear as a device in /dev/gpt/
> What have I not understood?
> I have a theory - label the partitions before creating the zpool, and
> add  them to the zpool afterwas by a /dev/gpt/ name. Except I have lost
> confidence that the label would appear in /dev/gpt/. It could be that
> /dev/gpt names don't appear if they're part of a zpool.
> However, testing this theory is going to involve hassle (i.e. the
> destruction and rebuilding of the entire zpool) so if anyone could tell
> me if I'm heading in the right direction I'd appreciate it. I may well
> have missed something trivial here.
> Thanks, Frank.

[1] pp. 30-35 and [3] pp. 4-8 discuss various choices for labels, and 
recommend meaningful GPT label strings set manually by the 
administrator.  For example, [3] p. 6:

# gpart add -t freebsd-zfs -l zfs-mirror-1 da2

If you've used GPT partitioning on the drives in your zpool, it might be 
possible to add GPT labels now.  For example, [3] p. 6:

# gpart modify -i 2 -l f01-serialnum da2

Both [1] and [3] discuss the fact that a given drive, partition, file 
system, etc., can be identified in various ways, manual or automatic, 
but the kernel will pick one and "wither" the rest.  Once a GPT label is 
set manually, other methods should be disabled via settings in 
/boot/loader.conf and the system rebooted ([1] p. 35):


I'd suggest experimenting with USB flash drives on another machine.


[1]  Michael W. Lucas, 2014, "FreeBSD Mastery: Storage Essentials",

[2]  Michael W. Lucas & Allan Jude, 2015, "FreeBSD Mastery: ZFS",

[3]  Allan Jude & Michael W. Lucas, 2015, "FreeBSD Mastery: Advanced 

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