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RN214 OS6.10.10 Snapshots
I found this post from 2021, but I am not seeing what I expect from snapshots. I have had this config for a long time, let's assume >2Y. I expected a monthly snapshot to be retained, as the d...
It's acting as if it's doing pruning -- like it believed you were running out of space. Are there any warnings in the log about running out of space? Note that with BTRFS, you need to worry about both data and metadata use. Perhaps you are running low metadata. From SSH, what do btrfs filesystem df /data and btrfs filesystem usage /data show (assuming your volume is named data)?
Are you doing periodic defrags, and did one occur just prior to the mass deletions? Defrag and long-term snapshot retention don't go together well. Snapshots not taking much real space relies on the fact that most of the data doesn't change, and the snapshot simply points to most of the same sectors as the active data, not all different ones. Defrag moves the active sectors around, but cannot tell the snapshots where they moved to, so the snapshots still point to (and thus retain as in use) the old locations while the active data marks other sectors as in use.
Backups of some types of files that are large but don't have a lot of changes can also cause a lot of unnecessary content duplication. Large drive images and encryption volumes are examples.
Yes, something triggered the mass deletion, it seems quite random, I can't see anything in the lofs that would indicate a reason (so I am quite baffled đ).
I don't believe there is any issue with free storage space, I generally do not delete anything on the NAS (it's mainly photos, family video, music, etc). Here is the live info
~# btrfs filesystem df /data
Data, single: total=8.79TiB, used=8.79TiB
System, RAID1: total=32.00MiB, used=992.00KiB
Metadata, RAID1: total=1.00GiB, used=8.00MiB
Metadata, DUP: total=1.00GiB, used=432.16MiB
GlobalReserve, single: total=68.25MiB, used=0.00B
~# btrfs filesystem usage /data
Overall:
Device size: 14.54TiB
Device allocated: 8.80TiB
Device unallocated: 5.74TiB
Device missing: 0.00B
Used: 8.79TiB
Free (estimated): 5.75TiB (min: 2.88TiB)
Data ratio: 1.00
Metadata ratio: 2.00
Global reserve: 68.25MiB (used: 0.00B)
Data,single: Size:8.79TiB, Used:8.79TiB
/dev/md126 784.00GiB
/dev/md127 8.03TiB
Metadata,RAID1: Size:1.00GiB, Used:8.00MiB
/dev/md126 1.00GiB
/dev/md127 1.00GiB
Metadata,DUP: Size:1.00GiB, Used:432.16MiB
/dev/md127 2.00GiB
System,RAID1: Size:32.00MiB, Used:992.00KiB
/dev/md126 32.00MiB
/dev/md127 32.00MiB
Unallocated:
/dev/md126 2.87TiB
/dev/md127 2.87TiB
The status.log shows a defrag 21/Aug/2026 - the log goes back to 5/Oct/2023 (which is when I reset and reinitialised the system), so again, no real clues there (yet).
Any other thought of where to look?
I will consider the custom snapshots as StephenBâ mentions, but I'd love to get to the bottom of this too.
Looking at status.log again, I observe the snapshot deletions (clearouts) seem to happen soon after a reboot:
I haven't yet run my script to check the ages, but here is a snip:
[25/05/06 19:38:25 WEST] notice:system:LOGMSG_SYSTEM_HALT The system is shutting down. [25/05/22 10:54:04 WEST] info:snapshot:LOGMSG_SMART_SNAPSHOT_DELETE_INFO Snapshot prune worker successfully deleted snapshot 2025_04_23__00_00_05 from share or LUN Shared. [25/05/22 10:54:05 WEST] info:snapshot:LOGMSG_SMART_SNAPSHOT_DELETE_INFO Snapshot prune worker successfully deleted snapshot 2025_04_22__00_00_03 from share or LUN Shared. [25/05/22 10:54:05 WEST] info:snapshot:LOGMSG_SMART_SNAPSHOT_DELETE_INFO Snapshot prune worker successfully deleted snapshot 2025_04_21__00_00_01 from share or LUN Shared. [25/05/22 10:54:05 WEST] info:snapshot:LOGMSG_SMART_SNAPSHOT_DELETE_INFO Snapshot prune worker successfully deleted snapshot 2025_04_20__00_00_29 from share or LUN Shared. [25/05/22 10:54:06 WEST] info:snapshot:LOGMSG_SMART_SNAPSHOT_DELETE_INFO Snapshot prune worker successfully deleted snapshot 2025_04_18__00_00_28 from share or LUN Shared. [25/05/22 10:54:06 WEST] info:snapshot:LOGMSG_SMART_SNAPSHOT_DELETE_INFO Snapshot prune worker successfully deleted snapshot 2025_04_16__00_00_25 from share or LUN Shared. [25/05/22 10:54:07 WEST] info:snapshot:LOGMSG_SMART_SNAPSHOT_DELETE_INFO Snapshot prune worker successfully deleted snapshot 2025_04_09__00_00_28 from share or LUN Shared. [25/05/22 10:54:19 WEST] info:system:LOGMSG_START_READYNASD ReadyNASOS background service started. [25/06/21 13:00:14 WEST] info:snapshot:LOGMSG_SMART_SNAPSHOT_DELETE_INFO Snapshot prune worker successfully deleted snapshot 2025_04_26__00_00_05 from share or LUN Shared. [25/06/21 14:00:22 WEST] info:snapshot:LOGMSG_SMART_SNAPSHOT_DELETE_INFO Snapshot prune worker successfully deleted snapshot 2025_03_19__00_00_02 from share or LUN Shared. [25/06/21 15:00:31 WEST] info:snapshot:LOGMSG_SMART_SNAPSHOT_DELETE_INFO Snapshot prune worker successfully deleted snapshot 2025_02_28__00_00_20 from share or LUN Shared. [25/06/21 17:00:39 WEST] info:snapshot:LOGMSG_SMART_SNAPSHOT_DELETE_INFO Snapshot prune worker successfully deleted snapshot 2025_01_31__00_00_13 from share or LUN Shared. [25/06/22 00:01:22 WEST] notice:system:LOGMSG_SYSTEM_HALT The system is shutting down. [25/06/24 14:50:28 WEST] info:snapshot:LOGMSG_SMART_SNAPSHOT_DELETE_INFO Snapshot prune worker successfully deleted snapshot 2024_11_30__00_00_19 from share or LUN Shared. [25/06/24 14:50:43 WEST] info:system:LOGMSG_START_READYNASD ReadyNASOS background service started. [25/06/25 06:50:37 WEST] info:snapshot:LOGMSG_SMART_SNAPSHOT_DELETE_INFO Snapshot prune worker successfully deleted snapshot 2024_10_25__00_00_14 from share or LUN Shared. [25/06/25 07:50:45 WEST] info:snapshot:LOGMSG_SMART_SNAPSHOT_DELETE_INFO Snapshot prune worker successfully deleted snapshot 2024_09_15__00_00_25 from share or LUN Shared. [25/06/25 08:50:53 WEST] info:snapshot:LOGMSG_SMART_SNAPSHOT_DELETE_INFO Snapshot prune worker successfully deleted snapshot 2024_08_26__00_00_22 from share or LUN Shared. [25/06/25 09:51:01 WEST] info:snapshot:LOGMSG_SMART_SNAPSHOT_DELETE_INFO Snapshot prune worker successfully deleted snapshot 2024_07_29__00_00_14 from share or LUN Shared. [25/06/26 12:51:09 WEST] info:snapshot:LOGMSG_SMART_SNAPSHOT_DELETE_INFO Snapshot prune worker successfully deleted snapshot 2024_06_30__00_00_16 from share or LUN Shared. [25/06/26 13:51:17 WEST] info:snapshot:LOGMSG_SMART_SNAPSHOT_DELETE_INFO Snapshot prune worker successfully deleted snapshot 2024_05_31__00_00_05 from share or LUN Shared. [25/06/27 15:51:26 WEST] info:snapshot:LOGMSG_SMART_SNAPSHOT_DELETE_INFO Snapshot prune worker successfully deleted snapshot 2024_04_20__00_00_15 from share or LUN Shared. [25/06/28 17:51:34 WEST] info:snapshot:LOGMSG_SMART_SNAPSHOT_DELETE_INFO Snapshot prune worker successfully deleted snapshot 2024_03_28__00_00_07 from share or LUN Shared. [25/06/29 20:51:42 WEST] info:snapshot:LOGMSG_SMART_SNAPSHOT_DELETE_INFO Snapshot prune worker successfully deleted snapshot 2024_02_24__00_00_08 from share or LUN Shared. [25/06/30 09:51:51 WEST] info:snapshot:LOGMSG_SMART_SNAPSHOT_DELETE_INFO Snapshot prune worker successfully deleted snapshot 2024_01_25__00_00_14 from share or LUN Shared. [25/06/30 10:51:59 WEST] info:snapshot:LOGMSG_SMART_SNAPSHOT_DELETE_INFO Snapshot prune worker successfully deleted snapshot 2023_12_31__00_00_43 from share or LUN Shared. [25/06/30 14:52:07 WEST] info:snapshot:LOGMSG_SMART_SNAPSHOT_DELETE_INFO Snapshot prune worker successfully deleted snapshot 2023_11_27__00_00_04 from share or LUN Shared. [25/07/05 10:52:16 WEST] info:snapshot:LOGMSG_SMART_SNAPSHOT_DELETE_INFO Snapshot prune worker successfully deleted snapshot 2023_10_30__00_00_22 from share or LUN Shared. [26/02/21 07:25:03 WET] notice:system:LOGMSG_SYSTEM_HALT The system is shutting down. [26/02/22 08:36:42 WET] info:system:LOGMSG_START_READYNASD ReadyNASOS background service started. [26/02/23 00:00:13 WET] info:snapshot:LOGMSG_SNAPSHOT_CREATE_INFO Snapshot c_1771804811 was successfully created for share or LUN Shared. [26/02/26 00:00:11 WET] info:snapshot:LOGMSG_SNAPSHOT_CREATE_INFO Snapshot c_1772064010 was successfully created for share or LUN Shared. [26/03/01 00:00:43 WET] info:snapshot:LOGMSG_SNAPSHOT_CREATE_INFO Snapshot c_1772323243 was successfully created for share or LUN Shared. [26/03/15 12:40:56 WET] info:snapshot:LOGMSG_SMART_SNAPSHOT_DELETE_INFO Snapshot prune worker successfully deleted snapshot 2026_02_15__00_00_43 from share or LUN Shared. [26/03/25 17:42:07 WET] info:snapshot:LOGMSG_SMART_SNAPSHOT_DELETE_INFO Snapshot prune worker successfully deleted snapshot 2026_02_23__00_00_11 from share or LUN Shared. [26/03/29 14:42:38 WEST] info:snapshot:LOGMSG_SMART_SNAPSHOT_DELETE_INFO Snapshot prune worker successfully deleted snapshot 2026_03_01__00_00_43 from share or LUN Shared. [26/03/30 16:42:46 WEST] info:snapshot:LOGMSG_SMART_SNAPSHOT_DELETE_INFO Snapshot prune worker successfully deleted snapshot 2026_02_26__00_00_10 from share or LUN Shared. [26/04/18 10:44:21 WEST] info:snapshot:LOGMSG_SMART_SNAPSHOT_DELETE_INFO Snapshot prune worker successfully deleted snapshot 2026_02_21__00_00_08 from share or LUN Shared. [26/04/19 11:44:29 WEST] info:snapshot:LOGMSG_SMART_SNAPSHOT_DELETE_INFO Snapshot prune worker successfully deleted snapshot 2025_12_27__00_00_18 from share or LUN Shared. [26/04/22 09:44:37 WEST] info:snapshot:LOGMSG_SMART_SNAPSHOT_DELETE_INFO Snapshot prune worker successfully deleted snapshot 2025_11_27__00_00_23 from share or LUN Shared. [26/04/24 10:44:46 WEST] info:snapshot:LOGMSG_SMART_SNAPSHOT_DELETE_INFO Snapshot prune worker successfully deleted snapshot 2025_10_30__00_00_09 from share or LUN Shared. [26/04/24 20:44:54 WEST] info:snapshot:LOGMSG_SMART_SNAPSHOT_DELETE_INFO Snapshot prune worker successfully deleted snapshot 2025_09_24__00_00_07 from share or LUN Shared. [26/04/25 10:45:02 WEST] info:snapshot:LOGMSG_SMART_SNAPSHOT_DELETE_INFO Snapshot prune worker successfully deleted snapshot 2025_08_28__00_00_00 from share or LUN Shared. [26/04/25 11:45:10 WEST] info:snapshot:LOGMSG_SMART_SNAPSHOT_DELETE_INFO Snapshot prune worker successfully deleted snapshot 2025_07_24__00_00_21 from share or LUN Shared.Do you periodically run balance and scrubs?
Generally no, but I did in Aug'26 - note, all the original snapshots were deleted before that:
[26/08/21 12:08:04 WEST] notice:volume:LOGMSG_BALANCE_STARTED_VOLUME Balance started for volume data. [26/08/21 12:08:06 WEST] notice:volume:LOGMSG_BALANCE_COMPLETED_VOLUME Balance complete for volume data. [26/08/21 12:08:51 WEST] notice:volume:LOGMSG_DEFRAGSTART_VOLUME Defragmentation started for volume data. [26/08/21 12:20:00 WEST] notice:volume:LOGMSG_DEFRAGEND_VOLUME Defragmentation complete for volume data. ... [26/09/08 07:47:19 WEST] notice:volume:LOGMSG_SCRUBSTARTED_VOLUME Scrub started for volume data. [26/09/08 19:40:14 WEST] notice:volume:LOGMSG_SCRUBSTOP_VOLUME Scrub stopped for volume data.Note, I aborted the scrub as progress on display showed little progress after 12h (single digit %).
Generally no, but I did in Aug'26
I aborted the scrub as progress on display showed little progress after 12h (single digit %).
It seems odd that the balance would have completed in 2 seconds, especially if you don't routinely run it.
Might be worth running a btrfs scrub from ssh (letting it run to completion). Sometimes it can take a very long time (as Sandsharkâ recently reported).
Generally it looks like the auto-deletion volume safety triggered. AFAIK that only happens when free space is exhausted. Though it could maybe also trigger if metadata space runs too low???
Do you normally have volume quota enabled? If not, maybe do that, so you can see the amount of snapshot space for each share.
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