ZFS: OpenZFS: lost the ability to boot a BE

Allan Jude allanjude at freebsd.org
Tue Mar 31 00:01:15 UTC 2020


To temporarily mount a ZFS filesystem:

mount -t zfs poolname/data/set /path/here


On 2020-03-30 19:53, Graham Perrin wrote:
> On 30/03/2020 19:47, Graham Perrin wrote:
>> I lost the ability to boot the environment named 'r357746', I suspect
>> this occurred after I set it to use OpenZFS in lieu of ZFS.
>>
>> I would like to edit its /boot/loader.conf (revert to zfs_load="YES")
>> but re: https://github.com/openzfs/zfs/issues/4553 I can not think of
>> a way to mount the dataset.
>>
>> Please, how can I proceed?
> 
> Whilst booted from a different environment, I mounted the dataset whilst
> in single user mode, edited /boot/loader.conf … a little tricky, because
> after the mount I could no longer use zfs commands (ZFS library
> initialisation failed, words to that effect). Then beadm to activate the
> BE, and shutdown -r now
> 
> Success :-)
> 
> With zfs_load="YES" (in lieu of openzfs_load="YES") the BE is usable.
> 
>> ----
>>
>> Re: ZFS: destroying snapshots without compromising boot environments
>>
>> On 28/03/2020 15:36, Graham Perrin wrote:
>>> On 28/03/2020 15:19, Allan Jude wrote:
>>>
>>> > You can try to destroy the snapshot, if it is the basis of a clone,
>>> then
>>> > you will get an error, that you'd need to destroy the BE first, so you
>>> > might decide to keep that snapshot. As long as you don't use the -R
>>> flag
>>> > to zfs destroy dataset at snapshot, it will not destroy the clones.
>>> >
>>> > You can also use 'zfs promote' to make the clone into the parent,
>>> making
>>> > the original parent into the clone. This allows you to destroy that
>>> > original and the snapshot while keeping the clone.
>>>
>>> Perfect, thank you. I was nervous about destruction without warning.
>>>
>>> Below, are the differences (in measurement) between beadm and bectl
>>> to be expected?
>>>
>>> ----
>>>
>>> root at momh167-gjp4-8570p:~ # beadm list
>>> BE       Active Mountpoint  Space Created
>>> Waterfox -      -           15.9G 2020-03-10 18:24
>>> r357746f -      -            1.3G 2020-03-20 06:19
>>> r359249b NR     /           74.7G 2020-03-28 01:19
>>> root at momh167-gjp4-8570p:~ # beadm list -aDs
>>> BE/Dataset/Snapshot                            Active Mountpoint
>>> Space Created
>>>
>>> Waterfox
>>>   copperbowl/ROOT/Waterfox                     -      - 137.0M
>>> 2020-03-10 18:24
>>>     r359249b at 2020-03-17-21:57:17               -      - 59.2G
>>> 2020-03-17 21:57
>>>   copperbowl/ROOT/Waterfox at 2020-03-20-06:19:45 -      - 67.0M
>>> 2020-03-20 06:19
>>>
>>> r357746f
>>>   copperbowl/ROOT/r357746f                     -      - 1.2G
>>> 2020-03-20 06:19
>>>     Waterfox at 2020-03-20-06:19:45               -      - 59.2G
>>> 2020-03-20 06:19
>>>
>>> r359249b
>>>   copperbowl/ROOT/r359249b at 2020-03-17-21:57:17 -      - 15.7G
>>> 2020-03-17 21:57
>>>   copperbowl/ROOT/r359249b                     NR     / 59.0G
>>> 2020-03-28 01:19
>>> root at momh167-gjp4-8570p:~ # bectl list
>>> BE       Active Mountpoint Space Created
>>> Waterfox -      -          204M  2020-03-10 18:24
>>> r357746f -      -          1.21G 2020-03-20 06:19
>>> r359249b NR     /          74.7G 2020-03-28 01:19
>>> root at momh167-gjp4-8570p:~ # bectl list -aDs
>>> BE/Dataset/Snapshot                              Active Mountpoint
>>> Space Created
>>>
>>> Waterfox
>>>   copperbowl/ROOT/Waterfox                       -      - 204M
>>> 2020-03-10 18:24
>>>   Waterfox at 2020-03-20-06:19:45                   -      - 67.0M
>>> 2020-03-20 06:19
>>>
>>> r357746f
>>>   copperbowl/ROOT/r357746f                       -      - 1.21G
>>> 2020-03-20 06:19
>>>
>>> r359249b
>>>   copperbowl/ROOT/r359249b                       NR     / 74.7G
>>> 2020-03-28 01:19
>>>   r359249b at 2020-03-17-21:57:17                   -      - 15.7G
>>> 2020-03-17 21:57
>>> root at momh167-gjp4-8570p:~ # zfs list -t snapshot
>>> NAME                                                     USED AVAIL 
>>> REFER  MOUNTPOINT
>>> copperbowl/ROOT/Waterfox at 2020-03-20-06:19:45            67.0M - 59.2G  -
>>> copperbowl/ROOT/r359249b at 2020-03-17-21:57:17            15.7G - 59.2G  -
>>> copperbowl/iocage/releases/12.0-RELEASE/root at jbrowsers     8K - 1.24G  -
>>> copperbowl/poudriere/jails/head at clean                    328K - 1.89G  -
>>> root at momh167-gjp4-8570p:~ # zfs destroy
>>> copperbowl/ROOT/r359249b at 2020-03-17-21:57:17
>>> cannot destroy 'copperbowl/ROOT/r359249b at 2020-03-17-21:57:17':
>>> snapshot has dependent clones
>>> use '-R' to destroy the following datasets:
>>> copperbowl/ROOT/r357746f
>>> copperbowl/ROOT/Waterfox at 2020-03-20-06:19:45
>>> copperbowl/ROOT/Waterfox
>>> root at momh167-gjp4-8570p:~ # date ; uname -v
>>> Sat Mar 28 15:30:57 GMT 2020
>>> FreeBSD 13.0-CURRENT #1 r359249: Tue Mar 24 00:12:27 GMT 2020
>>> root at momh167-gjp4-8570p:/usr/obj/usr/src/amd64.amd64/sys/GENERIC-NODEBUG
>>> root at momh167-gjp4-8570p:~ #
>>>
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-- 
Allan Jude

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