Hi paolo, I test window guest with ide device with the following config,trim with ide drive failed.
1 The host fs is ext4 with discard option: /dev/sdb1 on /home/sdb type ext4 (rw,relatime,discard,data=ordered) 2 qemu config : ide drive with discard open x86_64-softmmu/qemu-system-x86_64 -enable-kvm -name win7 -M pc-0.15 -m 1024 -smp 2 -boot c -device piix3-usb-uhci,id=usb,bus=pci.0,addr=0x1.0x2 -drive file=/home/win7_base.qcow2,if=ide,index=0,format=qcow2,id=ad -drive file=/home/sdb/raw.img,if=ide,index=1,format=raw,id=hd,discard=on -monitor stdio -vga qxl -vnc :1 -device usb-tablet,id=input0 3 In win7 guest,init drive d,fill it with files,then shift+del files 4 The file /home/sdb/raw.img does not become small,when listing with -s option. It seems that the windows ntfs does not send trim to ide controller. No IDE_DMA_TRIM request received. Is there any config wrong? Btw,I found the info from the URL: http://msdn.microsoft.com/en-us/library/windows/desktop/hh848053(v=vs.85).aspx Qemu can do the same thing like hyper-v with windows guest? Thanks baiqing > -----Original Message----- > From: Paolo Bonzini [mailto:pbonz...@redhat.com] > Sent: Tuesday, July 23, 2013 2:35 PM > To: Libaiqing > Cc: qemu-devel@nongnu.org > Subject: Re: trim in windows guest witch virtio > > Il 23/07/2013 03:05, Libaiqing ha scritto: > > Hi paolo, > > Recently I test trim function,and it works well in linux guest with ext4 > fs. > > > > How to test it in windows guest? I got some info like this: > > 1 windows7 can send discard command when the storage device is > ssd; > > 2 find a tool like 'fstrim', 'TRIM' the volume manually. > > I think it only works with IDE and AHCI on Windows. You need a filter > driver to send it on SCSI disks. > > Paolo