Discussion:
[ceph-users] Is it still unsafe to map a RBD device on an OSD server?
Sebastien Han
2014-06-10 16:46:43 UTC
Permalink
Hi all,

A couple of years ago, I heard that it wasn?t safe to map a krbd block on an OSD host.
It was more or less like mounting a NFS mount on the NFS server, we can potentially end up with some deadlocks.

At least, I tried again recently and didn?t encounter any problem.

What do you think?

Cheers.
????
S?bastien Han
Cloud Engineer

"Always give 100%. Unless you're giving blood."

Phone: +33 (0)1 49 70 99 72
Mail: sebastien.han at enovance.com
Address : 11 bis, rue Roqu?pine - 75008 Paris
Web : www.enovance.com - Twitter : @enovance

-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 496 bytes
Desc: Message signed with OpenPGP using GPGMail
URL: <http://lists.ceph.com/pipermail/ceph-users-ceph.com/attachments/20140610/a4237024/attachment.pgp>
Jean-Charles LOPEZ
2014-06-10 16:51:37 UTC
Permalink
Hi S?bastien,

still the case. Depending on what you do, the OSD process will get to a hang and will suicide.

Regards
JC
Post by Sebastien Han
Hi all,
A couple of years ago, I heard that it wasn?t safe to map a krbd block on an OSD host.
It was more or less like mounting a NFS mount on the NFS server, we can potentially end up with some deadlocks.
At least, I tried again recently and didn?t encounter any problem.
What do you think?
Cheers.
????
S?bastien Han
Cloud Engineer
"Always give 100%. Unless you're giving blood."
Phone: +33 (0)1 49 70 99 72
Mail: sebastien.han at enovance.com
Address : 11 bis, rue Roqu?pine - 75008 Paris
_______________________________________________
ceph-users mailing list
ceph-users at lists.ceph.com
http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
John Wilkins
2014-06-10 18:49:06 UTC
Permalink
Sebastian,

It's actually not an issue with Ceph, but with the Linux kernel itself. If
you want to do this and avoid a deadlock, just use a VM on the same host to
mount the block device.

Regards,


John


On Tue, Jun 10, 2014 at 9:51 AM, Jean-Charles LOPEZ <jeanchlopez at mac.com>
Post by Jean-Charles LOPEZ
Hi S?bastien,
still the case. Depending on what you do, the OSD process will get to a
hang and will suicide.
Regards
JC
Post by Sebastien Han
Hi all,
A couple of years ago, I heard that it wasn?t safe to map a krbd block
on an OSD host.
Post by Sebastien Han
It was more or less like mounting a NFS mount on the NFS server, we can
potentially end up with some deadlocks.
Post by Sebastien Han
At least, I tried again recently and didn?t encounter any problem.
What do you think?
Cheers.
????
S?bastien Han
Cloud Engineer
"Always give 100%. Unless you're giving blood."
Phone: +33 (0)1 49 70 99 72
Mail: sebastien.han at enovance.com
Address : 11 bis, rue Roqu?pine - 75008 Paris
_______________________________________________
ceph-users mailing list
ceph-users at lists.ceph.com
http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
_______________________________________________
ceph-users mailing list
ceph-users at lists.ceph.com
http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
--
John Wilkins
Senior Technical Writer
Intank
john.wilkins at inktank.com
(415) 425-9599
http://inktank.com
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.ceph.com/pipermail/ceph-users-ceph.com/attachments/20140610/d2ccf24f/attachment.htm>
Sebastien Han
2014-06-10 21:20:20 UTC
Permalink
Thanks for your answers :)

????
S?bastien Han
Cloud Engineer

"Always give 100%. Unless you're giving blood."

Phone: +33 (0)1 49 70 99 72
Mail: sebastien.han at enovance.com
Address : 11 bis, rue Roqu?pine - 75008 Paris
Post by John Wilkins
Sebastian,
It's actually not an issue with Ceph, but with the Linux kernel itself. If you want to do this and avoid a deadlock, just use a VM on the same host to mount the block device.
Regards,
John
Hi S?bastien,
still the case. Depending on what you do, the OSD process will get to a hang and will suicide.
Regards
JC
Post by Sebastien Han
Hi all,
A couple of years ago, I heard that it wasn?t safe to map a krbd block on an OSD host.
It was more or less like mounting a NFS mount on the NFS server, we can potentially end up with some deadlocks.
At least, I tried again recently and didn?t encounter any problem.
What do you think?
Cheers.
????
S?bastien Han
Cloud Engineer
"Always give 100%. Unless you're giving blood."
Phone: +33 (0)1 49 70 99 72
Mail: sebastien.han at enovance.com
Address : 11 bis, rue Roqu?pine - 75008 Paris
_______________________________________________
ceph-users mailing list
ceph-users at lists.ceph.com
http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
_______________________________________________
ceph-users mailing list
ceph-users at lists.ceph.com
http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
--
John Wilkins
Senior Technical Writer
Intank
john.wilkins at inktank.com
(415) 425-9599
http://inktank.com
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 496 bytes
Desc: Message signed with OpenPGP using GPGMail
URL: <http://lists.ceph.com/pipermail/ceph-users-ceph.com/attachments/20140610/1837dbc5/attachment.pgp>
Mikaël Cluseau
2014-06-11 09:46:08 UTC
Permalink
Post by Sebastien Han
Thanks for your answers
ummmm I have that for an apt-cache since more than 1 year now, never had
an issue. Of course, your question is not about having a krbd device
backing an OSD of the same cluster ;-)
-------------- next part --------------
A non-text attachment was scrubbed...
Name: mcluseau.vcf
Type: text/x-vcard
Size: 344 bytes
Desc: not available
URL: <http://lists.ceph.com/pipermail/ceph-users-ceph.com/attachments/20140611/4e31d00a/attachment.vcf>
Loading...