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How to determine size of snapshots
I know snapshot management has improved a lot and I really took advantage of the new settings when they came out. I liked the weekly option and self pruning.
But I have read the FAQ's and KB's...
It's almost impossible to determine the disk space used by a particular snapshot. Browsing as you suggest won't give you the right answer.
Overall, the more the share changes, the more space the snapshots will take. That's because data blocks are held in common across the snapshots and the main share. Read through this link, it should give you some understanding on what's going on: https://community.netgear.com/t5/Using-your-ReadyNAS-in-Business/ReadyNAS-312-Need-Help-Understanding-Snapshots/m-p/936586#M171850
Defragmenting a share will increase the size needed by the snapshots, because when a file is defragmented BTRFS will duplicate any blocks held in common (so the version in the main share won't share any blocks with the snapshots).
Also, if you have files that are modified in place, the share containing them shouldn't have snapshots enabled. The snapshots will balloon, and the main share will quickly become very fragmented. One example here is a share used for torrent downloads.
Another aspect is that the "smart" snapshots will retain monthly snapshots forever (which is actually not so smart).
I recommend using custom snapshots, and explicitly limit retention. Most of my shares are set to 3 months of retention, the share I use for PC image backups is limited to two weeks. With these settings, snapshots take about 5% of the space used in my main NAS - though of course the amount used depends on how often your files are deleted and modified. But you could use them as starting points, and then tune the settings to get the right balance of retention and space needed.
If you decide to manually delete snapshots, then delete the oldest ones first. The 1.5 TB of deletions likely is the main culprit, as the space used by those files certainly migrated to the snapshots. It doesn't matter when the snapshots were created - what matters is when the files in the snapshot were modified or deleted. When a snapshot is created it uses no disk space - all the data is held in common with the main share. Over time that changes, as files in the main share are deleted or modified.
I got busy with things and have not gotten back to this so have not setup custom snapshots yet or deleted any.
When I checked, I was surprised to see that my snapshots have not automatically been deleted as I use monthly snapshots? Do those not automatically delete if "smart"? It has been over a month? I now have snapshots totaling 2.2TB out of my 9.09TB total capacity.
I either need to delete snapshots or add 2 drives....but the non-pro Seagate Ironwolf 14TB is still not on the approved list so stuck. I know if I buy the 12TB version the 14TB will be approved the next day! :smileyhappy:
In the meantime I have 2 readynas NAS's and can't do a major windows update until I can do additional backups....
Thanks,
BJB
BJB wrote:
When I checked, I was surprised to see that my snapshots have not automatically been deleted as I use monthly snapshots? Do those not automatically delete if "smart"? It has been over a month? I now have snapshots totaling 2.2TB out of my 9.09TB total capacity.
When you use "smart" snapshots, the monthly snapshots are never deleted. That's why I don't recommend using them.
So just manually delete all the snapshots older than your desired retention, and switch to "custom" snapshots.
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