[sheepdog-users] qemu 1.4 does not pass sync to sheepdog (was: sheepdog replication got stuck)

Gerald Richter - ECOS richter at ecos.de
Wed Jan 8 06:30:53 CET 2014

> Old QEMU doesn't support object cache or not support it well. To verify if
> your work with object cache. Please try:
> 1 starupt sheepdog with object cache enabled
> 2 run a vm with QEMU option '-drive cache=writeback'
> 3 generate some big file(several GB is good enough) inside VM
> 4 try 'dog vdi cache info' to see how much data are dirty for this VM
> 5 inside VM, execute 'sync' in bash
> 6 after sync returns, try 'dog vdi cache info' to see if dirty data are gone
> 7 shutdown your VM
> 8 try 'dog vdi cache info' to see the cache for this vm is released completely
> 9 reboot the VM and see if the changes are still there

I made these tests and everything is working fine, except the sync command, which does not cause a cache flush. Cache is flushed after it goes above 40MB and is removed after shutdown and changes are still there after reboot.

So you are right, my qemu version is not fully working regarding the object cache, but this is not related to the original problem I reported (see my other mail)



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