[sheepdog-users] Object Cache Question

[Bastian Scholz]

Ping?

Anyone has an idea or hint, while enabling
Object Cache has this impact on performance?

Cheers

Bastian

Am 2014-03-11 09:42, schrieb Bastian Scholz:
> Hi List,
> 
> I try around with object cache of sheepdog in my
> Testcluster (3 nodes, copies=3).
> 
> For this, I start an additional gateway sheep
> process on one node (separated disk for cache but
> same type as the obj disks). But when enabling
> Object Cache, the rw performance of random 4k
> rw drops to 1/10th of the speed without OC enabled.
> 
> # sheep --version
> Sheepdog daemon version 0.7.7
> 
> # qemu --version
> QEMU emulator version 1.1.2 (Debian 1.1.2+dfsg-6a)
> 
> # virsh --version
> 0.9.12.3
> 
> qemu cache setting is none (managed by libvirt), but
> it didnt make any noticeable difference when set to
> writeback or writethrough...
> 
> # sheep /mnt/soeren/3/ -g -p 7003
> # fio guest results
> read : io=11612KB, bw=594415 B/s, iops=145 , runt= 20004msec
> write: io=11804KB, bw=604243 B/s, iops=147 , runt= 20004msec
> 
> # sheep /mnt/soeren/3/ -g -p 7003 -w size=10G
> # fio guest results
> read : io=1172.0KB, bw=59934 B/s, iops=14 , runt= 20024msec
> write: io=1256.0KB, bw=64230 B/s, iops=15 , runt= 20024msec
> 
> For comparison the fio results of the sheep
> cache directory.
> 
> read : io=10576KB, bw=541355 B/s, iops=132 , runt= 20005msec
> write: io=10712KB, bw=548317 B/s, iops=133 , runt= 20005msec
> 
> Any Ideas whats wrong? Maybe some Problems with
> the old QEMU Version?
> 
> Cheers
> Bastian