snapshot strange behaviour
Hello,
During doing backups I found strange behaviour... 2.6.37, latest btrfs- progs from git
nbgentoo ~ # btrfs subv crea a
Create subvolume './a'
nbgentoo ~ # cd a
nbgentoo a # btrfs subv crea b
Create subvolume './b'
nbgentoo a # touch b/file
nbgentoo a # ls -l b/
total 0
-rw-r--r-- 1 root root 0 Jan 23 08:14 file
nbgentoo a # cd ..
nbgentoo ~ # btrfs subv snap a x
Create a snapshot of 'a' in './x'
nbgentoo ~ # ls -l x/b/
total 0
and also
nbgentoo ~ # cd x/
nbgentoo x # btrfs subv dele b
ERROR: 'b' is not a subvolume
Is this a bug or intended behaviour and I am missing something something? How to snapshot a subvolume, containing another subvolumes?
(I create subvolume backup, under this another subvolumes as not always I want to snapshot the whole backup subvolume).
Thank you
Lubos
Hi Lubos,
Quoted 20 lines · Lubos Kolouch
Hello,
During doing backups I found strange behaviour... 2.6.37, latest btrfs- progs from git
nbgentoo ~ # btrfs subv crea a
Create subvolume './a'
nbgentoo ~ # cd a
nbgentoo a # btrfs subv crea b
Create subvolume './b'
nbgentoo a # touch b/file
nbgentoo a # ls -l b/
total 0
-rw-r--r-- 1 root root 0 Jan 23 08:14 file
nbgentoo a # cd ..
nbgentoo ~ # btrfs subv snap a x
Create a snapshot of 'a' in './x'
nbgentoo ~ # ls -l x/b/
total 0
Quoted 8 lines
and also
nbgentoo ~ # cd x/
nbgentoo x # btrfs subv dele b
ERROR: 'b' is not a subvolumeIs this a bug or intended behaviour and I am missing something something? How to snapshot a subvolume, containing another subvolumes?
It is the intended behavior. The snapshotting is not recursive about subvolumes. If you snapshot a subvolume which contains another one, you got only the content of the first subvolume.
The directory "x/b" which you see, is not the subvolume "b" snapshotted, but only the "mount-point" of "b".
Quoted 14 lines
(I create subvolume backup, under this another subvolumes as not always I want to snapshot the whole backup subvolume).
Thank you
Lubos
--
To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
.
Goffredo Baroncelli, Sun, 23 Jan 2011 13:17:13 +0100:
Quoted 28 lines
Hi Lubos,
Quoted 25 lines · Lubos Kolouch
Hello,
During doing backups I found strange behaviour... 2.6.37, latest btrfs- progs from git
nbgentoo ~ # btrfs subv crea a
Create subvolume './a'
nbgentoo ~ # cd a
nbgentoo a # btrfs subv crea b
Create subvolume './b'
nbgentoo a # touch b/file
nbgentoo a # ls -l b/
total 0
-rw-r--r-- 1 root root 0 Jan 23 08:14 file nbgentoo a # cd .. nbgentoo ~ # btrfs subv snap a x
Create a snapshot of 'a' in './x'
nbgentoo ~ # ls -l x/b/
total 0and also
nbgentoo ~ # cd x/
nbgentoo x # btrfs subv dele b
ERROR: 'b' is not a subvolume
Quoted 9 lines
Quoted 2 lines
Is this a bug or intended behaviour and I am missing something something? How to snapshot a subvolume, containing another subvolumes?
It is the intended behavior. The snapshotting is not recursive about subvolumes. If you snapshot a subvolume which contains another one, you got only the content of the first subvolume. The directory "x/b" which you see, is not the subvolume "b" snapshotted, but only the "mount-point" of "b".
Hi Goffredo,
I understand. But then I think btrfs should refuse to do it or at least print a warning. Otherwise it is very inconvenient for the user, having to search for any subvolumes down the tree...
Lubos
Quoted 17 lines · Lubos Kolouch
Goffredo Baroncelli, Sun, 23 Jan 2011 13:17:13 +0100:
Quoted 5 lines
Hi Lubos,
Quoted 1 line · Lubos Kolouch
Hello,
Quoted 9 lines
Quoted 2 lines
Is this a bug or intended behaviour and I am missing something something? How to snapshot a subvolume, containing another subvolumes?
It is the intended behavior. The snapshotting is not recursive about subvolumes. If you snapshot a subvolume which contains another one, you got only the content of the first subvolume. The directory "x/b" which you see, is not the subvolume "b" snapshotted, but only the "mount-point" of "b".
Quoted 5 lines
Hi Goffredo,
I understand. But then I think btrfs should refuse to do it or at least print a warning. Otherwise it is very inconvenient for the user, having to search for any subvolumes down the tree...
Sorry, but I can't agree. To me it seems a reasonable default. There are a lot of cases where I would not snapshot a sub-sub-subvolume: my rootfs is a subvolume, my home is in another one. I can snapshot, update the root fs, then if something goes wrong I can roolback to the old one, without affecting my home.
This behavior is strictly related to the btrfs internal.
Any way it is true that this behavior should be highlighted in the documentation.
And more, it is possible to add a "-R" flag to snapshot recursively a subvolume...
Goffredo
Quoted 8 lines
Lubos
--
To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
.
Also, btrfs already has a utility to scan for subvolumes in a directory
btrfs subvolume list /path
Quoted 10 lines · Goffredo Baroncelli
Quoted 9 lines · Lubos Kolouch
Goffredo Baroncelli, Sun, 23 Jan 2011 13:17:13 +0100:
Quoted 7 lines
Hi Lubos,
Quoted 4 lines · Lubos Kolouch
Hello,
Is this a bug or intended behaviour and I am missing something something? How to snapshot a subvolume, containing another subvolu=
mes?
Quoted 2 lines
Quoted 2 lines
Quoted 2 lines
It is the intended behavior. The snapshotting is not recursive abou=
t
Quoted 1 line
Quoted 1 line
Quoted 1 line
subvolumes. If you snapshot a subvolume which contains another one,=
you
Quoted 1 line
Quoted 1 line
Quoted 1 line
got only the content of the first subvolume. The directory "x/b" wh=
ich
Quoted 7 lines
Quoted 7 lines
Quoted 3 lines
you see, is not the subvolume "b" snapshotted, but only the "mount-point" of "b".
Hi Goffredo,
I understand. But then I think btrfs should refuse to do it or at le=
ast
Quoted 1 line
Quoted 1 line
print a warning. Otherwise it is very inconvenient for the user, hav=
ing to
Quoted 4 lines
Quoted 1 line
search for any subvolumes down the tree...
Sorry, but I can't agree. To me it seems a reasonable default. There =
are
Quoted 1 line
a lot of cases where I would not snapshot a sub-sub-subvolume: my roo=
tfs
Quoted 6 lines
is a subvolume, my home is in another one. I can snapshot, update the root fs, then if something goes wrong I can roolback to the old one, without affecting my home.
This behavior is strictly related to the btrfs internal.
Quoted 12 lines
Any way it is true that this behavior should be highlighted in the documentation.
And more, it is possible to add a "-R" flag to snapshot recursively a subvolume...
Goffredo
Quoted 4 lines
Lubos
--
To unsubscribe from this list: send the line "unsubscribe linux-btrf=
s" in
Quoted 7 lines
Quoted 4 lines
the body of a message to [email protected]
More majordomo info at =A0http://vger.kernel.org/majordomo-info.html .--
To unsubscribe from this list: send the line "unsubscribe linux-btrfs=
" in
Quoted 3 lines
the body of a message to [email protected]
More majordomo info at =A0http://vger.kernel.org/majordomo-info.html
--
To unsubscribe from this list: send the line "unsubscribe linux-btrfs" = in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Goffredo Baroncelli, Sun, 23 Jan 2011 19:02:11 +0100:
Quoted 34 lines · Lubos Kolouch
Quoted 18 lines
Goffredo Baroncelli, Sun, 23 Jan 2011 13:17:13 +0100:
Quoted 9 lines
Hi Lubos,
Quoted 5 lines · Lubos Kolouch
Hello,
Is this a bug or intended behaviour and I am missing something something? How to snapshot a subvolume, containing another subvolumes?
Quoted 7 lines
It is the intended behavior. The snapshotting is not recursive about subvolumes. If you snapshot a subvolume which contains another one, you got only the content of the first subvolume. The directory "x/b" which you see, is not the subvolume "b" snapshotted, but only the "mount-point" of "b".
Quoted 5 lines
Hi Goffredo,
I understand. But then I think btrfs should refuse to do it or at least print a warning. Otherwise it is very inconvenient for the user, having to search for any subvolumes down the tree...
Sorry, but I can't agree. To me it seems a reasonable default. There are a lot of cases where I would not snapshot a sub-sub-subvolume: my rootfs is a subvolume, my home is in another one. I can snapshot, update the root fs, then if something goes wrong I can roolback to the old one, without affecting my home.
This behavior is strictly related to the btrfs internal.
Quoted 7 lines
Any way it is true that this behavior should be highlighted in the documentation.
And more, it is possible to add a "-R" flag to snapshot recursively a subvolume...
Goffredo
The -R would be nice... two use cases :
1) directory many_small_files under the /home subvolume, that you need only for a while - it is easier to for example delete it when it is subvolume as well
2) backups
subvolume backups -> subvolumes 20110122, 20110123, ...
you want to delete backups older than x years -> it is much faster to do if it is a subvolume as well. But - you may as well want to be able snapshot or delete the whole backups subvolume.
Lubos
Quoted 2 lines · Goffredo Baroncelli
And more, it is possible to add a "-R" flag to snapshot recursively a subvolume...
Are you saying recursive snapshot creation is aready supportted in btrfs? Which version?
Signature · 1 line
Fajar