On 03/28/17 15:41, Patrick O'Callaghan wrote: > On Tue, 2017-03-28 at 15:08 +0200, Laszlo Ersek wrote: >> On 03/28/17 14:21, Patrick O'Callaghan wrote: >>> On Tue, 2017-03-28 at 11:47 +0200, Laszlo Ersek wrote: >>>> I recommend the following setup: >>>> >>>> - hard disk(s): virtio-blk or virtio-scsi disk, as you prefer >>> >>> I'm interested in why someone would prefer one over the other. Can you >>> explain? >> >> I prefer virtio-scsi because it supports thin provisioning (UNMAP scsi >> operation); it lets me conserve space in host filesystems that support >> discard (such as ext4 or xfs, for example -- there may be more). Given >> the right configuration, if you delete files in your Windows 8 or >> Windows 10 VM, the space is eventually released on the host filesystem. > > OK, thanks. > >> With virtio-blk, the software stack is less featureful and thereby >> thinner, which is said by some to lead to better performance. Also, as >> far as I know, dataplane is only available for virtio-blk at the moment, >> it is in progress for virtio-scsi. (I could be out of date on that >> though.) YMMV. > > No idea what that is. As I'm not provisioning multiple high-load > servers, does this matter to me?
I couldn't give you more authoritative documentation than what google turns up, so please go ahead and search for it yourself. Personally, I have never ever set up virtio-blk dataplane, in my short or long term guests (some of which use GPU or other device assignment as well), and I have no complaints about IO performance. (I too don't run production servers, like you.) The bottleneck on my laptop has always been SSD capacity (even with two SSDs), which virtio-scsi (with unmap/discard enabled) has remedied impeccably. I guess, if you haven't complained to yourself about IO performance, don't bother with dataplane. Laszlo _______________________________________________ vfio-users mailing list [email protected] https://www.redhat.com/mailman/listinfo/vfio-users
