How does RBD cache work? I wasn't able to find an adequate explanation in the docs.
On Sunday, June 22, 2014, Mark Kirkwood <mark.kirkw...@catalyst.net.nz> wrote: > Good point, I had neglected to do that. > > So, amending my conf.conf [1]: > > [client] > rbd cache = true > rbd cache size = 2147483648 > rbd cache max dirty = 1073741824 > rbd cache max dirty age = 100 > > and also the VM's xml def to include cache to writeback: > > <disk type='network' device='disk'> > <driver name='qemu' type='raw' cache='writeback' io='native'/> > <auth username='admin'> > <secret type='ceph' uuid='cd2d3ab1-2d31-41e0-ab08-3d0c6e2fafa0'/> > </auth> > <source protocol='rbd' name='rbd/vol1'> > <host name='192.168.1.64' port='6789'/> > </source> > <target dev='vdb' bus='virtio'/> > <address type='pci' domain='0x0000' bus='0x00' slot='0x07' > function='0x0'/> > </disk> > > Retesting from inside the VM: > > $ dd if=/dev/zero of=/mnt/vol1/scratch/file bs=16k count=65535 oflag=direct > 65535+0 records in > 65535+0 records out > 1073725440 bytes (1.1 GB) copied, 8.1686 s, 131 MB/s > > Which is much better, so certainly for the librbd case enabling the rbd > cache seems to nail this particular issue. > > Regards > > Mark > > [1] possibly somewhat agressively set, but at least a noticeable > difference :-) > > On 22/06/14 19:02, Haomai Wang wrote: > >> Hi Mark, >> >> Do you enable rbdcache? I test on my ssd cluster(only one ssd), it seemed >> ok. >> >> dd if=/dev/zero of=test bs=16k count=65536 oflag=direct >>> >> >> 82.3MB/s >> >> >> > _______________________________________________ > ceph-users mailing list > ceph-users@lists.ceph.com > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com >
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