rename whilst in use

rename whilst in use

[Wolfgang Hennerbichler]

hi,

I've accidently renamed a rbd object that has been in use within a
kvm-domain.

After detaching the rbd object I could rename it, but the source seems
still to be around in space:

# rbd ls -l rd | grep mysql3
mysql3.new  12000M          2

# rbd create rd/test --size 1
# rbd rename rd/test rd/mysql3
rbd: rename error: 2013-02-27 13:53:29.817863 7f3424ba8780 -1 librbd:
rbd image mysql3 already exists
(17) File exists

unfortunately my scrollback buffer isn't long enough to find out about
the actual error I got during the first rename, but it should be easy to
reproduce.
I assume this is a bug, that's why I posted it to ceph-devel directly.

Wolfgang




-- 
DI (FH) Wolfgang Hennerbichler
Software Development
Unit Advanced Computing Technologies
RISC Software GmbH
A company of the Johannes Kepler University Linz

IT-Center
Softwarepark 35
4232 Hagenberg
Austria

Phone: +43 7236 3343 245
Fax: +43 7236 3343 250
wolfgang.hennerbichler@risc-software.at
http://www.risc-software.at

Re: rename whilst in use

[Josh Durgin]

On 02/27/2013 04:59 AM, Wolfgang Hennerbichler wrote:
> hi,
>
> I've accidently renamed a rbd object that has been in use within a
> kvm-domain.
>
> After detaching the rbd object I could rename it, but the source seems
> still to be around in space:
>
> # rbd ls -l rd | grep mysql3
> mysql3.new  12000M          2
>
> # rbd create rd/test --size 1
> # rbd rename rd/test rd/mysql3
> rbd: rename error: 2013-02-27 13:53:29.817863 7f3424ba8780 -1 librbd:
> rbd image mysql3 already exists
> (17) File exists

Since it doesn't appear in rbd ls, this suggests that the old
rbd_id.mysql3 object still exists.

> unfortunately my scrollback buffer isn't long enough to find out about
> the actual error I got during the first rename, but it should be easy to
> reproduce.

I can't reproduce it (at least not with format 2 images). Can you?
I'd expect this problem with format 1 images, since they don't separate
the header object from the name of the image.

> I assume this is a bug, that's why I posted it to ceph-devel directly.

Thanks, it certainly seems like a bug.

Josh

Re: rename whilst in use

[Wolfgang Hennerbichler]

On 02/27/2013 11:01 PM, Josh Durgin wrote:

> Since it doesn't appear in rbd ls, this suggests that the old
> rbd_id.mysql3 object still exists.

Yes. Is there a way I can safely delete it?

rados ls -p rd | grep mysql | less
mysql3.rbd
rbd_id.mysql3.new

=> here it is (and yes, it's format==1). can I just say rados rm ...
without having to fear that everything breaks down?

>> unfortunately my scrollback buffer isn't long enough to find out about
>> the actual error I got during the first rename, but it should be easy to
>> reproduce.
> 
> I can't reproduce it (at least not with format 2 images). Can you?

I currently only have this production system to play, so I can't really
try. but you're right, it's a format 1 image. (that was the use case, I
tried to "convert" a format 1 image to a format 2 image by creating the
.new and copying stuff over)

> I'd expect this problem with format 1 images, since they don't separate
> the header object from the name of the image.

so true. :)

> Thanks, it certainly seems like a bug.

as it's a format==1 bug, maybe it's of less importance. so: is rados rm
mysql3.rbd a good idea? :)

> Josh

Wolfgang

PS: I didn't receive mails (even not your reply) on the mailing-list for
about 12 hours, did your mailserver break? Is your mailserver backed by
ceph-fs? :)

Re: rename whilst in use

[Josh Durgin]

On 02/27/2013 10:01 PM, Wolfgang Hennerbichler wrote:
> On 02/27/2013 11:01 PM, Josh Durgin wrote:
>
>> Since it doesn't appear in rbd ls, this suggests that the old
>> rbd_id.mysql3 object still exists.
>
> Yes. Is there a way I can safely delete it?
>
> rados ls -p rd | grep mysql | less
> mysql3.rbd
> rbd_id.mysql3.new
>
> => here it is (and yes, it's format==1). can I just say rados rm ...
> without having to fear that everything breaks down?

If you've just had this problem with a format 1 image, you can safely
rados rm the old header (oldname.rbd). It's the only thing that wouldn't
be cleaned up by a rename while it's in use.

>>> unfortunately my scrollback buffer isn't long enough to find out about
>>> the actual error I got during the first rename, but it should be easy to
>>> reproduce.
>>
>> I can't reproduce it (at least not with format 2 images). Can you?
>
> I currently only have this production system to play, so I can't really
> try. but you're right, it's a format 1 image. (that was the use case, I
> tried to "convert" a format 1 image to a format 2 image by creating the
> .new and copying stuff over)
>
>> I'd expect this problem with format 1 images, since they don't separate
>> the header object from the name of the image.
>
> so true. :)
>
>> Thanks, it certainly seems like a bug.
>
> as it's a format==1 bug, maybe it's of less importance. so: is rados rm
> mysql3.rbd a good idea? :)

If mysql3 is the old name of the image that was renamed while in use,
yes.

>> Josh
>
> Wolfgang
>
> PS: I didn't receive mails (even not your reply) on the mailing-list for
> about 12 hours, did your mailserver break? Is your mailserver backed by
> ceph-fs? :)

Not yet :) I'm not sure why that happened, I didn't notice any issues
with vger or my other emails today.