Re: [Qemu-devel] [Important] Query regarding bdrv_co_discard

[Sanjay Kumar2]

Output of hdparam is below. Also let me know does network based protocol 
supports 'qcow2' format. As my block driver is network based. It is perfectly 
working for raw format. When I change the type='qcow2', then it is not working 
because bdrv_get_geometry() is returning 0. This I am talking about 
qemu-kvm-0.12.1.2.

address@hidden ~]# hdparm -I /dev/sda

/dev/sda:
SG_IO: bad/missing sense data, sb[]:  70 00 05 00 00 00 00 0a 00 00 00 00 20 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

ATA device, with non-removable media
Standards:
        Likely used: 1
Configuration:
        Logical         max     current
        cylinders       0       0
        heads           0       0
        sectors/track   0       0
        --
        Logical/Physical Sector size:           512 bytes
        device size with M = 1024*1024:           0 MBytes
        device size with M = 1000*1000:           0 MBytes
        cache/buffer size  = unknown
Capabilities:
        IORDY not likely
        Cannot perform double-word IO
        R/W multiple sector transfer: not supported
        DMA: not supported
        PIO: pio0

-----Original Message-----
From: Sanjay Kumar2 
Sent: Wednesday, September 03, 2014 4:11 PM
To: Stefan Hajnoczi
Cc: address@hidden
Subject: RE: [Qemu-devel] Query regarding bdrv_co_discard

Thanks Stefan.

I using the same. Below is the XML.

    <disk type='network' device='disk'>
      <driver name='qemu' type='raw' cache='none' io='native' discard='unmap'/>
      <source protocol='oflame' 
name='/dev/of/vdisk/{a30c3997-0ad8-4495-8549-68431abfa84a}'>
        <host name='10.209.133.163' port='9999'/>
      </source>
      <target dev='sda' bus='scsi'/>
      <address type='drive' controller='1' bus='0' target='0' unit='0'/>
    </disk>
....

    <controller type='scsi' index='1' model='virtio-scsi'>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x07' 
function='0x0'/>
    </controller>

I am able to see the scsi disk, /dev/sda inside the guest, but does not showing 
TRIM supported in the hdparm output.  Fstrim command is also failing.

Regards,
Sanjay

-----Original Message-----
From: Stefan Hajnoczi [mailto:address@hidden 
Sent: Wednesday, September 03, 2014 4:06 PM
To: Sanjay Kumar2
Cc: address@hidden
Subject: Re: [Qemu-devel] Query regarding bdrv_co_discard

On Tue, Sep 02, 2014 at 02:09:44AM -0700, Sanjay Kumar2 wrote:
> Please let me know how to test bdrv_co_discard interface. I mean what steps I 
> need to do on KVM host and inside guest to do end to end testing of this 
> interface. I have implemented a network protocol based block driver and 
> defined bdrv_co_discard interface as well which free the blocks on the remote 
> storage device.

Use a virtio-scsi storage controller and then the guest can send SCSI discard 
commands.  Make sure to use the -drive ...,discard=unmap option, otherwise 
discard commands are silently ignored.

Stefan