Re: whatever happened to yum + btrfs snapshotting?

2017-03-13 Thread Dusty Mabe

On 02/17/2015 07:53 AM, Neal Becker wrote:
> Some time back there was discussion of being able to rollback yum updates via 
> btrfs snapshotting.  As I recall, it turned out that the default btrfs 
> install 
> was not setup correctly to make this feasible (I had briefly tested it on my 
> machine).  I haven't heard anything since - this seems like a great idea.
> 

I've been using it for years. It takes a special setup, but works pretty well.

http://dustymabe.com/2017/02/12/fedora-btrfssnapper-the-fedora-25-edition/

I do use some patches in grub from suse to take advantage of everything I need
which is documented here:

https://github.com/dustymabe/fedora-grub-boot-btrfs-default-subvolume/tree/master/fedora25

Dusty
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Re: whatever happened to yum + btrfs snapshotting?

2015-02-17 Thread Chris Murphy
On Tue, Feb 17, 2015 at 2:40 PM, Matěj Cepl mc...@cepl.eu wrote:
 On 2015-02-17, 13:17 GMT, Josh Boyer wrote:
 Now, it is possible to do this in dnf (either with btrfs or with dm
 snapshots) but I'm not aware of anyone working on it.  Fedora has the
 Snapper tool available in the repos, which could do snapshotting
 outside of dnf as well.

 Yeah, just that I was told by people who should know that
 snapper was mainly developed by SUSE people so it is quite
 leaning towards BTRFS. Support of DM-thinp snapshots is there,
 but its quality is really not perfect.

Getting thin pool and volumes configured correctly for the many
snapshots that snapper produces is non-obvious and non-trivial. If you
don't do that correctly from the start, and near as I can tell the
installer doesn't configure it for snapshots, even a handful of
snapshots and writing into them will blow up the entire thin pool and
all LV's on it. There's no hand holding and it's not fail safe.

There are some btrfs multiple device gotchas (with device failures,
removal and replace) that are equally non-obvious and non-trivial. But
it's a neck deep swimming pool vs being thrown into the LVM thinp
ocean with giant waves. Btrfs snapshots are deceptively fast and safe.
Many snapshots or snapshots involving large files, can easily result
in significant underestimates of how much free space remains due to
the passive deduplication they imply. And that turns into logistical
problems for backing up and restoring, even with btrfs send/receive,
that are non-obvious and non-trivial.

Many snapshots also confuses the installer, for example:
https://bugzilla.redhat.com/show_bug.cgi?id=1185117
And that's with less than a day of life for a new openSUSE default
installation. Anyway, snapshot buyers beware!

I feel any future discussion of Btrfs by default needs an exception to
the usual way of doing changes: change is proposed and implemented
weeks before a branch. Instead, Btrfs should get months of Rawhide
testing before branch, by becoming default in Rawhide only sooner than
later. And this can explicitly acknowledge it being a non-committing
change for Fedora 23. This is less abrupt of a change and more fail
safe.

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Re: whatever happened to yum + btrfs snapshotting?

2015-02-17 Thread Neal Becker
Josh Boyer wrote:

 On Tue, Feb 17, 2015 at 7:53 AM, Neal Becker ndbeck...@gmail.com wrote:
 Some time back there was discussion of being able to rollback yum updates via
 btrfs snapshotting.  As I recall, it turned out that the default btrfs
 install was not setup correctly to make this feasible (I had briefly tested
 it on my
 machine).  I haven't heard anything since - this seems like a great idea.
 
 Well, yum is being retired in favor of dnf and btrfs still isn't the
 default filesystem because it still isn't stable enough.  So that's
 basically what happened.
 
 Now, it is possible to do this in dnf (either with btrfs or with dm
 snapshots) but I'm not aware of anyone working on it.  Fedora has the
 Snapper tool available in the repos, which could do snapshotting
 outside of dnf as well.
 
 josh

My recollection was that snapshots on btrfs worked, but it was difficult to 
really do the rollback because the snapshots were stored inside the root as a 
subtree, or something to this effect - and that to work nicely the original 
btrfs install needed to be done differently?

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Re: whatever happened to yum + btrfs snapshotting?

2015-02-17 Thread Vít Ondruch
Dne 17.2.2015 v 13:53 Neal Becker napsal(a):
 Some time back there was discussion of being able to rollback yum updates via 
 btrfs snapshotting.  As I recall, it turned out that the default btrfs 
 install 
 was not setup correctly to make this feasible (I had briefly tested it on my 
 machine).  I haven't heard anything since - this seems like a great idea.


yum-plugin-fs-snapshot should be what you are looking for.


Vít
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Re: whatever happened to yum + btrfs snapshotting?

2015-02-17 Thread Matěj Cepl
On 2015-02-17, 13:17 GMT, Josh Boyer wrote:
 Now, it is possible to do this in dnf (either with btrfs or with dm
 snapshots) but I'm not aware of anyone working on it.  Fedora has the
 Snapper tool available in the repos, which could do snapshotting
 outside of dnf as well.

Yeah, just that I was told by people who should know that 
snapper was mainly developed by SUSE people so it is quite 
leaning towards BTRFS. Support of DM-thinp snapshots is there, 
but its quality is really not perfect.

Matěj

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Re: whatever happened to yum + btrfs snapshotting?

2015-02-17 Thread Josh Boyer
On Tue, Feb 17, 2015 at 7:53 AM, Neal Becker ndbeck...@gmail.com wrote:
 Some time back there was discussion of being able to rollback yum updates via
 btrfs snapshotting.  As I recall, it turned out that the default btrfs install
 was not setup correctly to make this feasible (I had briefly tested it on my
 machine).  I haven't heard anything since - this seems like a great idea.

Well, yum is being retired in favor of dnf and btrfs still isn't the
default filesystem because it still isn't stable enough.  So that's
basically what happened.

Now, it is possible to do this in dnf (either with btrfs or with dm
snapshots) but I'm not aware of anyone working on it.  Fedora has the
Snapper tool available in the repos, which could do snapshotting
outside of dnf as well.

josh
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