Hi:
few years ago virtio-blk device was showing as hard-disk under
windows. recent years the driver change the device to show as
thin-provisioned disk. the change is good for ssd, but not so good
for raw hard-disk.
under windows server 2022 the default virtio-blk situation is quite
bad, ssd trim is very slow. and defrag a bigger volume like 1TB
harddisk will always show "memory not enough", even when the volume is
empty.
I found discussions to change the "discard_granularity" to make trim
happy again. and libvirt support the syntax like below:
<blockio discard_granularity='2097152'/>
I also found if I can set "discard_granularity" to zero, then
windows will recognize the device as "traditional hard drive" again
and won't do unnecessary trim to it. I want to do this for years, but
couldn't find a way to set it up like vitio-scsi's rotational
parameter.
the sad part is if I setup it under RHEL 9.4 with librirt 10.0 like below:
<blockio discard_granularity='0'/>
the line will just disappear when I close "virsh edit"
so I can only use complex format with "<qemu:override>" to set
"discard_granularity='0'"
I wonder if libvirt would be changed to accept
"discard_granularity='0'" so the traditional hard-disk can be
recognized under windows again.
or is there better ways to distinguish hard-disk/ssd/thin-disk
for virtio-blk now?
Regards,
tbskyd
