[sheepdog] question about replica recovery failure caused by oid.tmp file

[Bingpeng Zhu]

Thank you for the advice.
default_init() of sheep/store.c  has already had the logic of unlinking oid.tmp files. I'm not sure the reason why oid.tmp file still exists in the system.







------------------ Original ------------------
From:  "Hitoshi Mitake";<mitake.hitoshi at lab.ntt.co.jp>;
Date:  Sep 18, 2014
To:  "Ruoyu"<liangry at ucweb.com>; 
Cc:  "Bingpeng Zhu"<nkuzbp at foxmail.com>; "sheepdog"<sheepdog at lists.wpkg.org>; 
Subject:  Re: [sheepdog] question about replica recovery failure caused by oid.tmp file



At Tue, 16 Sep 2014 10:10:32 +0800,
Ruoyu wrote:
> 
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> Thanks Bingpeng.
> I also encountered this problem.
> I suggest sheep should scan oid.tmp files and remove them when it is 
> being started.

I agree with Ruoyu's opinion. .tmp files should be deleted at
initialization time. e.g. default_init() of sheep/store.c would be a
good place for it.

Thanks,
Hitoshi

> 
> On 2014?09?15? 00:14, Bingpeng Zhu wrote:
> > Hi, all:
> >      I have a problem in using sheepdog. I create a erasure coded VDI 
> > and write
> >   some data to it. Then, I unplug disk and stop/restart one sheep in a 
> > short
> >   time. After recovery is completed in the latest epoch, I find some 
> > replica is
> >   lost and only the corresponding oid.tmp file exists in the data 
> > directory. I tried
> >   to rebuild the replica using "dog vdi check", but it didn't work. I 
> > think it is
> >   caused by oid.tmp file. I have to delete the oid.tmp file manually 
> > and then
> >   "dog vdi check" successfully recoverd the lost replica.
> >       In function default_create_and_write() of sheep/plain_store.c, 
> > it returns
> >   success directly if oid.tmp file exists. I have read the comment in 
> > this function carefully,
> >   it says gateway and recovery thread may try to write the SAME data, 
> > so it is okay
> >   to simply return success here. To solve this problem, I want to 
> > change the code of
> > default_create_and_write() so that replica data will be written even 
> > oid.tmp file exists.
> >   If oid.tmp exists, the function should overwrite it.
> > I am not sure if this change will work good for all scenario. 
> > Especially, I doubt whether
> >   this change will lead to old data overwriting new data. But I 
> > haven't thought out any scenario
> >   that will lead to old data overwriting new data. Can someone give me 
> > some advice to solve this problem?
> >
> >
> >
> 
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