[sheepdog] ledger object leak

[Hitoshi Mitake]

At Fri, 24 Oct 2014 11:01:41 +0800,
Ruoyu wrote:
> 
> According to current sheepdog's rule, deleting a vdi, no matter it is 
> snapshot or not, its vdi object, in another word, ledger object, will 
> not be removed from disks.

The below objects described in Valerio's mail are inode objects. But
as you say, ledger objects are not guaranteed to be deleted
always. Deleting entire family or cluster format is the only way to
remove them all.

> 
> I think it is necessary for collecting allocated vdi in node recovery. 
> Otherwise, the deleted vdi id might be reused. However, because data 
> objects are copy-on-write, the allocated vdi id probably belongs to 
> other vdi so that the deleted vdi id must not be reused.

Yes, reusing VDI ID is not allowed. But terribly, it was remained as a
bug and fixed in the recent commit:
21549a1bd4981fabcc09d062a647162127fe0637
:(

> 
> Therefore, it is not a bug. But it is still a good question.

Some users require the feature for cleaning inodes for reducing
recovery traffic and recycling VDI ID safely. Let's discuss about the
feature soon.

Thanks,
Hitoshi

> 
> On 2014年10月24日 06:01, Valerio Pachera wrote:
> > Hi, this isn't urgent but I opened a bug as a reminder:
> > https://bugs.launchpad.net/sheepdog-project/+bug/1384951
> >
> > Correct me if I'm wrong: as a workaround, when there are no snapshots
> > I can safely remove all ledger objects but the last.
> >
> > cd /mnt/sheep/0
> > ls 8*
> > 807c2b2500000000
> > 807c2b2700000000
> > 807c2b2900000000
> > 807c2b2a00000000
> > 807c2b2b00000000
> > 807c2b2c00000000
> > 807c2b2e00000000
> > 807c2b2f00000000
> >
> > ls 8* | grep -v 807c2b2f00000000 | xargs rm
> >
> > Thank you.
> 
> 
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