fstrim for Windows Guests and Ceph Storage

[starnetwork]

Hello,
how can I run fstrim solution for Windows KVM with Ceph storage?
the best is if possible to run it In a constant timing

Thanks!

 

[Klaus Steinberger]

discard is possible with virtio-scsi, but only with 2012 / Vista upwards

Windows 7 and Windows 2008R2 (and older ones of course) don't support the scsi unmap command.
(they support s-ata trim, but that is not supported in sata and virtio-blk driver)

with Windows server 2012 the optimization is usually run on a scheduled task
look for the "optimize drives" tool

so the answer is yes but not with Windows 7 or older

 

[starnetwork]

Hi,
thanks for that response!
as you can see at the screenshot, discard is disabled, Ceph + Virtio + OS Type: Win10/2016

any suggestion?
os should be power Off for that?

 

[Klaus Steinberger]

You seem to use the virtio-blk driver (which does not support trim and may get deprecated)

Do the following:

-> add a additional dummy disk with virtio-scsi driver
-> install the virtio-scsi driver in the WIndows VM via device manager
-> remove the dummy disk again

then:

shutdown the vm
detach the disk from the vm
add it again with virtio-scsi treiber and discard on

Ahh and hopefully you did a backup and/or snapshot of the VM before in case something goes wrong ......

 

[starnetwork]

Thanks Klaus!
I did and got for the Win2016 blue screen after moved to virtio-scsi
also, for the win2012 it's not detecting the virtIO scsi driver from the last and stable ISOs

suggestions?

 

[Klaus Steinberger]

you have to install the driver (as shown in my message) _before_ you move to virtio-scsi

Please read here: https://pve.proxmox.com/wiki/Windows_VirtIO_Drivers

 

[starnetwork]

sure, I did for the 2016
add dummy drive, install and remove the dummy drive
after that I moved the disks to virtio-scsi and try to boot

 

[Klaus Steinberger]

did you really add the dummy disk as virtio-scsi?

with some of the ISO's for virtio-win some time back I had the problem that the device-manager did not find the correct driver and installed an incorrect one.
Then you had to browse to the correct driver and os Version to get the correct version

 

[RCK]

discard is possible with virtio-scsi, but only with 2012 / Vista upwards

Windows 7 and Windows 2008R2 (and older ones of course) don't support the scsi unmap command.
(they support s-ata trim, but that is not supported in sata and virtio-blk driver)

I just tested discard with latest proxmox 5.3, and sata is now trimming correctly with win7/2008r2 !
So if you want to have discard working correctly you need to use local-lvm (thin) and:

1. os >= Win8/2012 + VirtIO SCSI controller + SCSI hdd + Discard option (best HDD perf)
2. os = Win7/2008r2 + VirtIO SCSI controller + SATA hdd + Discard option

 

[Rainerle]

Hi,

after reading your posts I reconfigured my Windows 7 and Server 2008r2 systems to use SATA on Ceph RBD storage.

...
bootdisk: sata0
ostype: win7
sata0: ceph-proxmox-VMs:vm-106-disk-0,cache=writeback,discard=on,size=30G
scsihw: virtio-scsi-pci
...

Using https://github.com/CyberShadow/trimcheck I was able to confirm that it works for both mentioned versions.

Unfortunatly the qm agent <VMID> fstrim command gives the following message:

root@proxmox01:~# qm agent 106 fstrim
{
"error" : {
"class" : "GenericError",
"desc" : "fstrim is only supported for Win8+"
}
}
root@proxmox01:~#

So I ran disk optimizer within the OS.

Overall I was able to save 11% of the total used space on the Ceph storage...

 

[RCK]

Well, I validate this behavious with:

• I setup on kvm with win7 "sata + discard" on one "local-lvm" + "thin pool" storage.
• my win7 doesn't have any agent, so I can't run "qm agent xxx fstrim"
• I made a backup of vm --> 20GB
• I copied a big 10 gb file on my vm, I made a backup --> 30 GB
• I delete the big 10 gb file on my vm, I made a backup --> 20GB again

 

[RCK]

Confirmed with another VM on Windows 7 and proxmox-ve: 5.3-1, discard is working well here with following conf:
Localt agent is not needed, nor fstrim command.

bootdisk: sata0
cores: 4
ide2: none,media=cdrom
keyboard: fr
memory: 8192
name: Generateur-Win7-202
net0: virtio=00:11:97:09:02:02,bridge=vmbr0
numa: 0
onboot: 1
ostype: win7
sata0: local-lvm:vm-202-disk-0,discard=on,size=110G
scsihw: virtio-scsi-pci
sockets: 1
tablet: 0
vga: std

 

[RCK]

Be carefull, even if "discard=on" is working with sata, there is a huge performance drop with sata vs scsi on Win7x64
My local test on SSD show me that sata driver is 2 to 4 x slower than scsi.