[Bug 1523246] Re: Virtio-blk does not support TRIM

[mohammadreza nasrabadi]

thanks. so now my question is that are these sparsed blocks rewritable? I mean 
after deletion of a file and downloading again, will these files be stored on 
the sparsed blocks or the number of starting block for write operation will be 
after the number of latest sparsed block?

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https://bugs.launchpad.net/bugs/1523246

Title:
  Virtio-blk does not support TRIM

Status in QEMU:
  Fix Released

Bug description:
  When model=virtio is used, TRIM is not supported.

  # mount -o discard /dev/vda4 /mnt
  # mount | tail -1
  /dev/vda4 on /mnt type fuseblk 
(rw,nosuid,nodev,relatime,user_id=0,group_id=0,allow_other,blksize=4096)
  # fstrim /mnt/
  fstrim: /mnt/: the discard operation is not supported

  Booting without model=virtio allows using TRIM (in Windows as well).

  Full QEMU line:

  qemu-system-x86_64 -enable-kvm -cpu host -bios
  /usr/share/ovmf/ovmf_x64.bin -smp 2 -m 7G -vga qxl -usbdevice tablet
  -net nic,model=virtio -net user -drive discard=unmap,detect-
  zeroes=unmap,cache=none,file=vms/win10.hd.img.vmdk,format=vmdk,if=virtio

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