On Sat, Jan 17, 2015 at 12:11:28AM +0100, Richard Taubo wrote: > On 16 Jan 2015, at 17:49, Cole Robinson <crobinso@xxxxxxxxxx> wrote: > > > > On 01/15/2015 04:29 PM, Richard Taubo wrote: > >> Hi! > >> > >> As mentioned in an earlier mail I have installed > >> KVM on a logical volume like this (CentOS 7): > >> [#] lvcreate -L 300G -n lv_vm1 VolGroup > >> [#] virt-install --name=vm1.mydomain.com \ > >> --disk path=/dev/VolGroup/lv_vm1 \ > >> --ram=8192 --os-type=linux --os-variant=rhel7 \ > >> --vcpus=8 --check-cpu \ > >> --network bridge:br0 --nographics \ > >> --location=/usr/local/src/linux_isos/CENTOS7/CentOS-7.0-1406-x86_64-Minimal.iso \ > >> --extra-args 'ks=http://www.mydomain.com/anaconda-ks.cfg ksdevice=eth0 \ > >> ip=192.168.19.2 netmask=255.255.255.192 dns=8.8.8.8 gateway=192.168.19.1 console=ttyS0,115200n8 serial’ > >> > >> I would like to run fstrim from within the VM client (I have fstrim working on the VM host machine). > >> Running fstrim from within the VM gives me errors like this: > >> "fstrim: /usr: FITRIM ioctl failed: Operation not supported" > >> > >> Is it possible to run fstrim on the VM client with the setup described above? > >> > >> Thanks for any feedback! > > > > There's some details here: > > > > http://dustymabe.com/2013/06/11/recover-space-from-vm-disk-images-by-using-discardfstrim/ > > > > I think it boils down to using a scsi disk, and using discard=unmap. The blog > > post doesn't say it but modern virt-install supports the --disk discard > > option, so you don't need to edit the XML separately. > > > Thanks for the link! > > In the comment section there are some comments on using fstrim vs mounting the filesystem with “discard” on the guest. > I assume that either fstrim or “discard” on the guest will REQUIRE virt-install with --disk discard on the host, correct? There's a bunch of things that need to happen: (1) Host RHEL >= 7 -- you've got this. (2) Guest RHEL also >= 7. (3) Using virtio-scsi disks. (4) <driver name="qemu" [...] discard="unmap"> in the libvirt XML. (5) Inside the guest, mount the filesystem with -o discard. Try dumping the libvirt XML of the guest and posting it. Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com libguestfs lets you edit virtual machines. Supports shell scripting, bindings from many languages. http://libguestfs.org _______________________________________________ virt-tools-list mailing list virt-tools-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/virt-tools-list
