[sheepdog-users] cache performance test
sirio81 at gmail.com
Tue Jun 25 12:16:15 CEST 2013
sheep -w size=20000 /mnt/sheep/meta/,/mnt/sheep/dsk02
/mnt/sheep/meta is a ssd disk. Cache it stored here. No objects are
stored on the same physical disk.
/mnt/sheep/dsk02 is a mechanical sata disk, 7200 rpm like all the
other hdd of the cluster.
This is my guest
qemu-system-x86_64 -enable-kvm -smp 2 -m 512 -drive
and is running on the node with the ssd.
vdi named 'big' is formatted with ext4 and is where is write.
I compare the write speed of the guest using cache, with the write
speed of the host writing directly on the ssd.
dd if=/dev/zero of=n bs=1M count=512 oflag=direct
Guest: 55 MB/s
Host: 130 MB/s
dd if=/dev/zero of=n bs=1M count=512
Guest: 103 MB/s
Host: 302 MB/s
Honestly I expected not to see such big difference (with oflag=direct)
between the two using cache.
What do you think?
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