ZFS snapshot - rollback problem

David Christensen dpchrist at holgerdanske.com
Fri Sep 11 19:52:21 UTC 2020

On 2020-09-11 02:31, Ludovit Koren wrote:

When you reply to a message, put at least one blank line before and 
after new text.  Without it,  the indentation levels get messed up by 
the various mailers these messages go through.

Also, please do not post people's e-mail address (mailer setting?).

> On Friday, September 11, 2020, David Christensen ... wrote:

>> On 2020-09-10 23:31, Ludovit Koren wrote:

>>> On Friday, September 11, 2020, David Christensen ... wrote:

>>>> On 2020-09-10 07:18, Ludovit Koren wrote:

>>>>> ~>uname -a
>>>>> FreeBSD XxX 11.3-STABLE FreeBSD 11.3-STABLE #1 r354607: Mon Nov 11
>>>>> 12:19:28 CET 2019     root at jedi:/usr/obj/usr/src/sys/HP  amd64

>> Did you partition the disk by hand, use the FreeBSD installer, or
>> something else?

>   If I remember correctly, using installer

I find it is better, faster, and cheaper to keep records.  A networked 
version control system is ideal for this.

>> mount
>>> zroot on / (zfs, local, nfsv4acls)
>>> devfs on /dev (devfs, local, multilabel)
>>> fdescfs on /dev/fd (fdescfs)
>>> procfs on /proc (procfs, local)
>>> linprocfs on /compat/linux/proc (linprocfs, local)
>>> zroot/usr on /usr (zfs, local, nfsv4acls)
>>> zroot/usr/home on /usr/home (zfs, local, nfsv4acls)
>>> zroot/var on /var (zfs, local, nfsv4acls)
>>> tmpfs on /var (tmpfs, local)
>>> map -hosts on /net (autofs)
>>> map -media on /media (autofs)
>>> tmpfs on /tmp (tmpfs, local)

>> zpool status
>>>     pool: zroot
>>>    state: ONLINE
>>> status: Some supported features are not enabled on the pool. The pool can
>>>           still be used, but some features are unavailable.
>>> action: Enable all features using 'zpool upgrade'. Once this is done,
>>>           the pool may no longer be accessible by software that does not
>>> support
>>>           the features. See zpool-features(7) for details.
>>>     scan: resilvered 0 in 0 days 00:00:00 with 0 errors on Sat Apr  6
>>> 20:39:05 2019
>>> config:
>>>           NAME         STATE     READ WRITE CKSUM
>>>           zroot        ONLINE       0     0     0
>>>             gpt/disk0  ONLINE       0     0     0
>>> errors: No known data errors

> zfs rollback zroot/swapdisk0 at 200909
> cannot rollback ´zroot/swapdisk0': out of space

I believe I have seen that error message before, but have no record of 
it and forget the details.

STFW I am unable to find any good hits.

The developer approach would be to install source and grep(1) for it.

> zfs rollback zroot at 200909
> nothing happens, even if I wait several hours, or it hangs, respectivelly

If the process is stuck in an infinite loop, top(1) will show it 
(consider the '-m' option and/or 'm' hotkey):

# top -S -s 10

The zpool(8) 'iostat' subcommand is useful for watching ZFS I/O:

# zpool iostat -v 10

There are many other userland tools for monitoring aspects of the system 
and/or processes; I need to learn more of them.

Given that you are using STABLE, you should probably seek support per 
handbook section 23.4.2.

If it were my computer, I would backup, wipe, install, and migrate to 


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