On 16/03/2015 07:19, Wen Congyang wrote: > On 03/13/2015 05:05 PM, Fam Zheng wrote: >> On Fri, 03/13 17:01, Wen Congyang wrote: >>> On 03/11/2015 02:49 PM, Fam Zheng wrote: >>>> On Wed, 03/11 14:44, Wen Congyang wrote: >>>>> On 03/03/2015 03:59 PM, Fam Zheng wrote: >>>>>> On Tue, 03/03 15:53, Wen Congyang wrote: >>>>>>> I test qcow2_make_empty()'s performance. The result shows that it may >>>>>>> take about 100ms(normal sata disk). It is not acceptable for COLO. So >>>>>>> I think disk buff is necessary(just use it to replace qcow2). >>>>>> >>>>>> Why not tmpfs or ramdisk? >>>>> >>>>> Another problem: >>>>> After failover, secondary write request will be written in (active disk)? >>>>> It is better to write request to (nbd target). Is there any feature can >>>>> be reused to implement it? >>>> >>>> You can use block commit or stream to move the data. >>> >>> Can the job stream move the data? I don't find the write ops in >>> block/stream.c. >> >> It is bdrv_co_copy_on_readv that moves data. > > Does the job stream move the data from base to top?
Yes. block-commit goes in the other direction. Paolo
