On Fri, Aug 10, 2012 at 8:30 PM, Paolo Bonzini <pbonz...@redhat.com> wrote: > 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". >
I think it works on any, You can of course not boot from a if=scsi disk in qemu, but any '-drive file=iscsi://...,if=scsi' should work as long as it is not the boot device. SCSI emulation in qemu picks this up via WRITESAME10/16 and then calls bdrv_aio_discard() block/iscsi.c is invoked for discard and then translates this back to a SBC UNMAP command it sends to the target. Now, block/iscsi.c does assume that any target that reports that it supports thin-provisioning actually implements UNMAP command. There could be targets that support thin-provision ing that does NOT support UNMAP and unly support discard via WRITESAME10/16 so at some stage I should send a patch to iscsi.c to check which commands the target supprots and use one of the supported ones instead of a blanket "you say you support thin-provisioning, I take that as confirmation you support SBC UNMAP" regards ronnie sahlberg
