Re: [Qemu-devel] virtio-scsi vs. virtio-blk

[Stefan Priebe - Profihost AG]

Hi,

i tried that but i then get:
kvm: -device 
scsi-block,bus=scsihw0.0,channel=0,scsi-id=0,lun=0,drive=drive-scsi0,id=scsi0: 
scsi-block: INQUIRY failed
kvm: -device 
scsi-block,bus=scsihw0.0,channel=0,scsi-id=0,lun=0,drive=drive-scsi0,id=scsi0: 
Device 'scsi-block' could not be initialized

VM start command was:
http://pastebin.com/raw.php?i=6WNLPemy

Stefan
Am 10.08.2012 12:30, schrieb Paolo Bonzini:
> Il 10/08/2012 12:28, Stefan Priebe - Profihost AG ha scritto:
> > I'm using iscsi. So no raw or qcow2.
>
> Ok, then you need to use scsi-block as your device instead of scsi-disk
> or scsi-hd.  This will disable the QEMU SCSI emulation and let your VM
> talk directly to the NAS.
>
> CCing Ronnie who may be interested in bug reports since I'm on holiday
> starting "soon".
>
> Paolo
>
> > Thanks,
> >
> > Stefan
> >
> > Am 10.08.2012 12:20, schrieb Paolo Bonzini:
> > > Il 10/08/2012 11:22, Stefan Priebe - Profihost AG ha scritto:
> > > > virtio-scsi is now working fine. Could you please help me to get discard
> > > > / trim running? I can't find any information what is needed to get
> > > > discard / trim working.
> > >
> > > You need to add discard_granularity=NNN, where NNN is usually 512 for
> > > raw and the cluster size (65536) for qcow2.
> > >
> > > However, discard is supported only for XFS on raw, and on qcow2 it will
> > > not reclaim space---the space will only be reused for future qcow2
> > > allocation.
> > >
> > > Better support for discard on raw (other filesystems + block devices),
> > > and more efficient support also on other formats is on my todo list for
> > > the future.  However, an efficient implementation unfortunately requires
> > > changes at all levels including the kernel.
> > >
> > > I hope to present something about it at KVM Forum.
> > >
> > > Paolo