On 2017年11月01日 19:31, ST wrote: > On Wed, 2017-11-01 at 19:17 +0800, Qu Wenruo wrote: >> >> On 2017年11月01日 19:04, ST wrote: >>> Hello, >>> >>> I read in different places that one should keep amount of snapshots low >>> - around 15-20. My question - is this limitation on total number of >>> snapshots on the system or only on related (parent<->child) chain of >>> snapshots? >> >> Independent subvolume doesn't count, and it's filesystem based. >> >> So only snapshots (with source exists, and still shares a lot of trees >> with source) counts. >> >> And if you have multiple btrfs fses, then the count should be based on >> each fs. >> >>> What I want to do is the following: create (and then rotate) last 7 >>> daily snapshots (and maybe 4 weekly) for each user in his /home dir. >>> For >>> around 100 users. So if limitation is only on related snapshots then I'm >>> OK since only each 7 (or maybe 7+4) of them are related which is well >>> under the 15-20 limit. However in total there could be 700 snapshots. So >>> what is true? >> >> You're OK since independent subvolumes won't cause too much stress for >> backref walk. >> >> The only thing you may need to consider is to limit the ability to >> reflink data between subvolumes. >> Like cp --reflink or even offline dedupe. > > Thank you very much! How can I limit this ability? (I'm on Debian9) > > All the best! No way to limit, unfortunately. Thanks, Qu
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