On 18 July 2013 00:04, Josh Durgin <[email protected]> wrote:
> You can verify that rbd_cache = true is set with the admin socket
> command 'config get rbd_cache'. You'd need to set
>
> admin socket = /path/to/socket
>
> in ceph.conf, then reattach the rbd device. librados will create the
> admin socket as long as the user running qemu isn't prevented by unix
> permissions, selinux, apparmor, etc.
>
>
Works like a charm.
>
> ceph.conf has entry:
>> [client]
>> rbd_cache = true
>>
>
> The ceph.conf entry isn't needed since qemu 1.2 when you've got
> cache=setting in the qemu command line.
I have created VM with KVM 1.1.2 and all I had was rbd_cache configured in
ceph.conf. Cache option in libvirt set to "none":
<disk type="network" device="disk">
<driver name="qemu" type="raw" cache="none"/>
<source
name="cinder_volumes/volume-f81d6108-d8c9-4e06-94ef-02b1943a873d"
protocol="rbd"/>
<auth username="cinder_volumes">
<secret type="ceph" uuid="9481a373-bef5-07e9-d156-d7d37bfed894"/>
</auth>
<target bus="virtio" dev="vda"/>
<serial>f81d6108-d8c9-4e06-94ef-02b1943a873d</serial>
</disk>
<disk type="network" device="disk">
<driver name="qemu" type="raw" cache="none"/>
<source
name="cinder_volumes/volume-9ab3e9b3-e153-447c-ab1d-2f8f9bae095c"
protocol="rbd"/>
<auth username="cinder_volumes">
<secret type="ceph" uuid="9481a373-bef5-07e9-d156-d7d37bfed894"/>
</auth>
<target bus="virtio" dev="vdb"/>
<serial>9ab3e9b3-e153-447c-ab1d-2f8f9bae095c</serial>
</disk>
Config settings received from admin socket show that cache is enabled. I
thought that without configuring libvirt with cache options it is not
possible to force kvm to use it. Can you explain it a little bit why it
works or claims to work?
regards
--
Maciej Gałkiewicz
Shelly Cloud Sp. z o. o., Sysadmin
http://shellycloud.com/, [email protected]
KRS: 0000440358 REGON: 101504426
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