I''m having some problems in Xen trying to create a new block script for
rbd devices (Ceph RBD) and using those devices in domUs. I''ve attached
the block-rbd script that I''ve created and placed in /etc/xen/scripts.
Basically, this should allow me to specify the following in my config file:
disk = [ ''rbd:image-name,hda,w'' ]
...where image-name is the name of an rbd image. The script uses
Ceph''s "rbd" command to map the image to a device (/dev/rbdN
where N is a number) and then feeds that to the xenstore commands necessary for
accessing the device. Everything seems to work fine - script runs, devices are
mapped, and xenstore gets updated - but I cannot see the disk in my HVM domU.
The only clue as to what might be wrong is the following entry in my
/var/log/xen/qemu-dm-<domU>.log file:
qemu: type (image format) ''rbd'' unknown for vbd
''/local/domain/0/backend/vbd/29/768/mode'' or image
''image-name''
There are a couple of puzzling things about this. First, the domU is getting
passed a block device in the form of /dev/rbd1, which it should be able to
access, so why does it care from the type/image format is? The block device is
no different than a phy: device with a physical HDD or an LVM volume, and, while
the setting for "type" is rbd, I don''t know why that would
impact it. Second, why is it referencing the "mode" node of the
xenstore tree for that backend device. That really doesn''t make any
sense - the vbd should be one level above that, and the mode is definitely set
to "w" for read-write (verified with with xenstore-ls).
Has anyone else used Ceph RBD to back Xen-based VMs? Or has anyone else
successfully added another type of block device to Xen with a script? Any hints
on where to go from here?
Thanks - Nick
--------
This e-mail may contain confidential and privileged material for the sole use of
the intended recipient. If this email is not intended for you, or you are not
responsible for the delivery of this message to the intended recipient, please
note that this message may contain SEAKR Engineering (SEAKR)
Privileged/Proprietary Information. In such a case, you are strictly prohibited
from downloading, photocopying, distributing or otherwise using this message,
its contents or attachments in any way. If you have received this message in
error, please notify us immediately by replying to this e-mail and delete the
message from your mailbox. Information contained in this message that does not
relate to the business of SEAKR is neither endorsed by nor attributable to
SEAKR.
