Re: hard-disk via virtio-blk under windows (discard_granularity=0)

Andrea Bolognani <abologna(a)redhat.com&gt; > I'd also be surprised if this only affected Windows. Wouldn't Linux > guests likely see a similar change in how the device is presented? I don't understand all the impact under windows. but defrag is the obvious part. by default windows will do disk optimization weekly. trim was fast when I was using windows 2019 with virtio-blk drivers at that time. and you could manually do traditional defrag to the device although it will also do unnecessary trim after defrag. But recent windows server 2019/2022 with recent virtio-blk driver, trim was very slow and a bigger disk like 1TB thin-device will just show "memory not enough" when defrag(but NTFS really need defrag). I don't know what/when changed the behavior. I found "discard_granularity" seems the saver for both cases. when I use linux I don't care since it won't do trim automatically. I need to mount with options or do fstrim for the device. and there is no need to defrag the hard-disk. Since there is no automatic part, I don't know if this is useful or not to distinguish hdd/sdd/thin-device under linux?