delete-older-than destroys inappropriate snapshots

[Tamas Papp]

$ apt-btrfs-snapshot list
Available snapshots:
@apt-snapshot-2014-05-21_10:28:38
@apt-snapshot-2014-05-21_15:35:10
@apt-snapshot-2014-05-21_22:27:11
@apt-snapshot-2014-05-22_08:03:10
@apt-snapshot-2014-05-22_16:18:19
@apt-snapshot-2014-05-22_20:33:33
@apt-snapshot-2014-05-23_10:53:46
@apt-snapshot-2014-05-23_16:18:06
@apt-snapshot-2014-05-24_09:11:51
@apt-snapshot-2014-05-24_09:12:32
@apt-snapshot-2014-05-24_09:49:25
@apt-snapshot-2014-05-24_12:19:05
@apt-snapshot-2014-05-24_12:19:44
@apt-snapshot-2014-05-24_12:31:31

$ apt-btrfs-snapshot list-older-than 1d
Available snapshots older than '1d':
@apt-snapshot-2014-05-21_10:28:38
@apt-snapshot-2014-05-21_15:35:10
@apt-snapshot-2014-05-21_22:27:11
@apt-snapshot-2014-05-22_08:03:10
@apt-snapshot-2014-05-22_16:18:19
@apt-snapshot-2014-05-22_20:33:33
@apt-snapshot-2014-05-23_10:53:46
@apt-snapshot-2014-05-23_16:18:06
@apt-snapshot-2014-05-24_09:11:51
@apt-snapshot-2014-05-24_09:12:32
@apt-snapshot-2014-05-24_09:49:25

$ date
Sat May 24 13:39:46 CEST 2014

The same is true for the 'delete-older-than' switch.

ProblemType: Bug
DistroRelease: Ubuntu 14.10
Package: apt-btrfs-snapshot 0.3.4.2
ProcVersionSignature: Ubuntu 3.15.0-2.6-generic 3.15.0-rc6
Uname: Linux 3.15.0-2-generic x86_64
ApportVersion: 2.14.2-0ubuntu4
Architecture: amd64
Date: Sat May 24 13:34:24 2014
InstallationDate: Installed on 2013-03-23 (426 days ago)
InstallationMedia: Ubuntu 13.04 "Raring Ringtail" - Alpha amd64 (20130321)
PackageArchitecture: all
SourcePackage: apt-btrfs-snapshot
UpgradeStatus: Upgraded to utopic on 2013-05-03 (385 days ago)

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Tamas Papp (tomposmiko)]

It has actually been fixed for a while.
At least in recent releases.

# apt-btrfs-snapshot delete-older-than 1d
Delete subvolume (no-commit): '/tmp/apt-btrfs-snapshot-mp-7e2mente/@apt-snapshot-2020-09-18_13:29:22'
Delete subvolume (no-commit): '/tmp/apt-btrfs-snapshot-mp-sy5zjd_t/@apt-snapshot-2020-09-18_14:27:05'
Delete subvolume (no-commit): '/tmp/apt-btrfs-snapshot-mp-6dsfzf10/@apt-snapshot-2020-09-18_14:27:29'
Delete subvolume (no-commit): '/tmp/apt-btrfs-snapshot-mp-qprhlmpv/@apt-snapshot-2020-09-18_14:28:43'
Delete subvolume (no-commit): '/tmp/apt-btrfs-snapshot-mp-pckyk9vw/@apt-snapshot-2020-09-18_14:31:07'
Delete subvolume (no-commit): '/tmp/apt-btrfs-snapshot-mp-7pej0agf/@apt-snapshot-2020-09-18_14:31:15'
Delete subvolume (no-commit): '/tmp/apt-btrfs-snapshot-mp-6busdmsx/@apt-snapshot-2020-09-18_22:06:09'
Delete subvolume (no-commit): '/tmp/apt-btrfs-snapshot-mp-4ar23moh/@apt-snapshot-2020-09-21_11:11:38'
Delete subvolume (no-commit): '/tmp/apt-btrfs-snapshot-mp-4rd9a6o6/@apt-snapshot-2020-09-22_06:42:01'
Delete subvolume (no-commit): '/tmp/apt-btrfs-snapshot-mp-m5xcx94q/@apt-snapshot-2020-09-22_22:44:18'
Delete subvolume (no-commit): '/tmp/apt-btrfs-snapshot-mp-ku1q9ctc/@apt-snapshot-2020-09-23_05:36:05'
Delete subvolume (no-commit): '/tmp/apt-btrfs-snapshot-mp-dkz8pavo/@apt-snapshot-2020-09-23_05:43:45'
Delete subvolume (no-commit): '/tmp/apt-btrfs-snapshot-mp-h_won84w/@apt-snapshot-2020-09-23_06:36:15'
Delete subvolume (no-commit): '/tmp/apt-btrfs-snapshot-mp-pl4hszo_/@apt-snapshot-2020-09-23_22:24:57'
Delete subvolume (no-commit): '/tmp/apt-btrfs-snapshot-mp-moy4y1l9/@apt-snapshot-2020-09-24_07:08:36'
Delete subvolume (no-commit): '/tmp/apt-btrfs-snapshot-mp-jvfkp6ae/@apt-snapshot-2020-09-24_10:38:54'
Delete subvolume (no-commit): '/tmp/apt-btrfs-snapshot-mp-oidw2g05/@apt-snapshot-2020-09-24_10:41:14'
Delete subvolume (no-commit): '/tmp/apt-btrfs-snapshot-mp-qtw5duet/@apt-snapshot-2020-09-24_17:55:35'

# date
Fri Sep 25 02:38:12 PM CEST 2020

# apt-btrfs-snapshot list
Available snapshots:
@apt-snapshot-2020-09-24_23:50:56
@apt-snapshot-2020-09-25_00:29:27
@apt-snapshot-2020-09-25_14:26:05

[Ansgar Bohmann (ansgar-bohmann)]

I experience the same problems with the list-older-than and delete-older-than commands.

Since delete-older-than is also called from /etc/cron.weekly/apt-btrfs-snapshot (also belonging to the same package), this cron-job just doesn't do what it should. Potentially, the all the available space fills up with old snapshots never being deleted. At the same time . That's quite an implication.

(Simply turning around the < line 205 in /usr/lib/python3/dist-packages/apt_btrfs_snapshot.py is not the solution. In that case, the command list always returns an empty list. Another side note: the docstrings in the source code use the incorrect spelling „then“ instead of „than“.)

[Ansgar Bohmann (ansgar-bohmann)]

Thanks Tamas! Sorry, I missed you reply #3 earlier. I'm using apt-btrfs-snapshot version 3.5.3 (according to apt show) on Focal (Ubuntu 20.04) and still experiencing these problems. Which version do you use?

[Tamas Papp (tomposmiko)]

ii apt-btrfs-snapshot 3.5.4 all Automatically create snapshot on apt operations

It is also Focal, but I'm pretty sure it's OK for a while.

[Ansgar Bohmann (ansgar-bohmann)]

How did you get 3.5.4 on Focal? But besides that, differences between the two versions are marginal. In particular, the actual Python code ( /usr/lib/python3/dist-packages/apt_btrfs_snapshot.py ) didn't change at all.

I did some further testing. Right now,

# apt-btrfs-snapshot list-older-than 1d

also works on my system. What doesn't work however, is any interval greater than 1d: 2d, 3d, 4d, 30d, 90d, … In all these cases an empty list is returned (at the moment right now).

What makes things even more strange: Scrolling back in same terminal window to what I've tried just a few hours ago, I have clear evidence, that the very same command

# apt-btrfs-snapshot list-older-than 1d

did return only two snapshots, one taken a bit less than 24 h ago, the other slightly older, omitting many other snapshots. I have no clue what caused this change. (No updates or other changes to any installed packages have been made between the two scenarios.)

[Tamas Papp (tomposmiko)]

> How did you get 3.5.4 on Focal?

Oops, I lied.
It's Groovy.

[Ansgar Bohmann (ansgar-bohmann)]

On my system, there are still issues running:

# apt-btrfs-snapshot list-older-than …d

After I didn't have any explanation for the behaviour I mentioned earlier, I delete all snapshot on my system. Over the past month, more and more new snapshots were created. I checked from time to time and list-older-than did work as expected for more than 30 days.

Two days ago I upgraded to Ubuntu 20.10 (Groovy Gorilla). Here's what I get now:

# apt-btrfs-snapshot list
Available snapshots:
@apt-snapshot-2020-10-05_14:36:46
@apt-snapshot-2020-10-07_00:46:30
@apt-snapshot-2020-10-07_16:13:40
@apt-snapshot-2020-10-12_17:20:46
@apt-snapshot-2020-10-14_01:09:54
@apt-snapshot-2020-10-14_11:57:39
@apt-snapshot-2020-10-14_11:57:40
@apt-snapshot-2020-10-14_15:29:28
@apt-snapshot-2020-10-16_02:02:21
@apt-snapshot-2020-10-16_22:40:26
@apt-snapshot-2020-10-16_22:42:10
@apt-snapshot-2020-10-21_00:39:28
@apt-snapshot-2020-10-21_00:41:01
@apt-snapshot-2020-10-21_00:43:22
@apt-snapshot-2020-10-21_15:18:29
@apt-snapshot-2020-10-21_15:49:19
@apt-snapshot-2020-10-22_16:01:06
@apt-snapshot-2020-10-23_13:06:50
@apt-snapshot-2020-10-26_10:19:15
@apt-snapshot-2020-10-27_14:42:40
@apt-snapshot-2020-10-28_16:38:02
@apt-snapshot-2020-10-28_16:39:36
@apt-snapshot-release-upgrade-groovy-2020-10-29_04:28:47
@apt-snapshot-release-upgrade-groovy-2020-10-29_04:28:50
@apt-snapshot-2020-10-29_04:28:50
@apt-snapshot-2020-10-29_04:28:51
@apt-snapshot-release-upgrade-groovy-2020-10-29_04:30:54
@apt-snapshot-2020-10-29_04:30:55
@apt-snapshot-2020-10-29_04:30:56
@apt-snapshot-2020-10-29_05:17:49
@apt-snapshot-2020-10-29_05:24:34
@apt-snapshot-2020-10-29_13:58:16
@apt-snapshot-2020-10-30_09:16:20
@apt-snapshot-2020-10-30_12:36:16
@apt-snapshot-2020-10-30_23:44:55
@apt-snapshot-2020-10-30_23:45:17

# apt-btrfs-snapshot list-older-than 1d
Available snapshots older than '1d':
@apt-snapshot-2020-10-05_14:36:46
@apt-snapshot-2020-10-07_00:46:30
@apt-snapshot-2020-10-07_16:13:40
@apt-snapshot-2020-10-12_17:20:46
@apt-snapshot-2020-10-14_01:09:54
@apt-snapshot-2020-10-14_11:57:39
@apt-snapshot-2020-10-14_11:57:40
@apt-snapshot-2020-10-14_15:29:28
@apt-snapshot-2020-10-16_02:02:21
@apt-snapshot-2020-10-16_22:40:26
@apt-snapshot-2020-10-16_22:42:10
@apt-snapshot-2020-10-21_00:39:28
@apt-snapshot-2020-10-21_00:41:01
@apt-snapshot-2020-10-21_00:43:22
@apt-snapshot-2020-10-21_15:18:29
@apt-snapshot-2020-10-21_15:49:19
@apt-snapshot-2020-10-22_16:01:06
@apt-snapshot-2020-10-23_13:06:50
@apt-snapshot-2020-10-26_10:19:15
@apt-snapshot-2020-10-27_14:42:40
@apt-snapshot-2020-10-28_16:38:02
@apt-snapshot-2020-10-28_16:39:36
@apt-snapshot-release-upgrade-groovy-2020-10-29_04:28:47
@apt-snapshot-release-upgrade-groovy-2020-10-29_04:28:50
@apt-snapshot-2020-10-29_04:28:50
@apt-snapshot-2020-10-29_04:28:51
@apt-snapshot-release-upgrade-groovy-2020-10-29_04:30:54
@apt-snapshot-2020-10-29_04:30:55
@apt-snapshot-2020-10-29_04:30:56
@apt-snapshot-2020-10-29_05:17:49
@apt-snapshot-2020-10-29_05:24:34
@apt-snapshot-2020-10-29_13:58:16
@apt-snapshot-2020-10-30_09:16:20
@apt-snapshot-202...