[Qemu-devel] Query regarding bdrv_co_discard

[Qemu-devel] Query regarding bdrv_co_discard

[Sanjay Kumar2]

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Hi,

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.

Thanks and Best Regards,
Sanjay Kumar

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Re: [Qemu-devel] Query regarding bdrv_co_discard

[Stefan Hajnoczi]

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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

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Re: [Qemu-devel] Query regarding bdrv_co_discard

[Sanjay Kumar2]

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:stefanha@gmail.com] 
Sent: Wednesday, September 03, 2014 4:06 PM
To: Sanjay Kumar2
Cc: qemu-devel@nongnu.org
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