[buildd-tools-devel] Bug#868883: schroot: btrfs-snapshot requires btrfs-snapshot-directory= but doesn't use it

[Roger Leigh]

On 23/07/17 14:44, Philipp Kern wrote:
> On 07/23/2017 02:38 PM, Roger Leigh wrote:
>> An unrelated FYI: On the schroot master branch, Btrfs snapshot support
>> has been removed.  The repeated Btrfs filesystem unbalancing with
>> intensive snapshotting made this feature unsuitable for production use.
>> I will be replacing it with ZFS snapshot support.
> 
> Isn't there a hope that snapshot support in btrfs will improve
> eventually? Or do you consider this an unfixable design flaw? Isn't it
> essentially a function of technology (SSD) and size of the disk (to
> ensure many block groups)?

Hi Phillip,

Honestly, I don't know if it will improve.  It hasn't to date that I'm 
aware of, and it's had this issue for many years.  It can of course be 
revisited and added back should it be fixed, but the very limited time I 
have for this has meant I've rationalised the supported chroot types to 
the ones needed for sbuild (directory, file), and dropped all the 
esoteric ones to reduce the support burden.

ZFS doesn't have these issues, and I've switched over to it for the last 
few years now after I got fed up with the ongoing Btrfs problems.  So 
when I do add a new snapshot type, it'll likely be ZFS.


Best wishes,
Roger