Reasonable amount of snapshots
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?
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?
Thank you!
Quoted 6 lines · ST
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.
Quoted 7 lines
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.
Thanks,
Qu
Quoted 8 lines
Thank you!
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Quoted 25 lines · Qu Wenruo
Quoted 6 lines · ST
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.
Quoted 7 lines
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?
Quoted 6 lines
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!
Quoted 29 lines · ST
Quoted 28 lines · Qu Wenruo
Quoted 6 lines · ST
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.
Quoted 7 lines
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.
Quoted 7 lines
Quoted 3 lines
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
Quoted 36 lines · Qu Wenruo
Quoted 33 lines · ST
Quoted 31 lines · Qu Wenruo
Quoted 6 lines · ST
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.
Quoted 7 lines
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.
Quoted 5 lines
Quoted 3 lines
Thank you very much! How can I limit this ability? (I'm on Debian9)
All the best!
No way to limit, unfortunately.
Well, it can obviously be "limited" by just not using cp --reflink all over the place and by not running dedupe on everything. The filesystem won't just start doing that by its own. ;]
Signature · 1 line
Hans van Kranenburg