Re: [Qemu-block] [Question] the problem about driver-mirror

[Stefan Hajnoczi]

On Thu, Apr 23, 2015 at 5:51 PM, 张敏 <address@hidden> wrote:
> I test the function of driver-mirror when run io stress test in vm.
> The fio's model is 128 iodepth, 4K block-size, 100% write, 100% randon.
> This is a continuous test, and then I start drive-mirror to copy data
> to other image file. I find this job can't finish.
> I analysis the problem and find the dirty bitmap is always set, the job
> can't converge.
> Any ideas to solve this problem?

You can use QEMU I/O throttling to limit writes to the guest's disk so
the mirror job can complete.

I don't have a magic number for you, but if you look at the rate at
which the block job runs, make sure that the guest write throughput is
limited below that number.

Stefan