[SOLVED] Cannot use Ramdisk for KVM storage

[smarteos]

Hello,

I have a fresh setup with Proxmox 3.0 (manual install over Debian 7), and cannot start a newly created KVM (Windows) guest VM with storage based on /run/shm (tmpfs filesystem).

This is the output of the start command :

kvm: -drive file=/run/shm/images/260/vm-260-disk-1.qcow2,if=none,id=drive-ide0,format=qcow2,aio=native,cache=none: could not open disk image /run/shm/images/260/vm-260-disk-1.qcow2: Invalid argument
TASK ERROR: start failed: command '/usr/bin/kvm -id 260 -chardev 'socket,id=qmp,path=/var/run/qemu-server/260.qmp,server,nowait' -mon 'chardev=qmp,mode=control' -vnc unix:/var/run/qemu-server/260.vnc,x509,password -pidfile /var/run/qemu-server/260.pid -daemonize -name xptmpfs1 -smp 'sockets=1,cores=1' -nodefaults -boot 'menu=on' -vga cirrus -k fr -m 512 -device 'piix3-usb-uhci,id=uhci,bus=pci.0,addr=0x1.0x2' -device 'usb-tablet,id=tablet,bus=uhci.0,port=1' -device 'virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x3' -drive 'if=none,id=drive-ide2,media=cdrom,aio=native' -device 'ide-cd,bus=ide.1,unit=0,drive=drive-ide2,id=ide2,bootindex=200' -drive 'file=/run/shm/images/260/vm-260-disk-1.qcow2,if=none,id=drive-ide0,format=qcow2,aio=native,cache=none' -device 'ide-hd,bus=ide.0,unit=0,drive=drive-ide0,id=ide0,bootindex=100' -netdev 'type=tap,id=net0,ifname=tap260i0,script=/var/lib/qemu-server/pve-bridge,vhost=on' -device 'virtio-net-pci,mac=D6:5A:56:B6:EE:B2,netdev=net0,bus=pci.0,addr=0x12,id=net0,bootindex=300' -rtc 'driftfix=slew,base=localtime'' failed: exit code 1

And here is pveversion -v :
pve-manager: 3.0-20 (pve-manager/3.0/0428106c)
running kernel: 2.6.32-20-pve
proxmox-ve-2.6.32: 3.0-100
pve-kernel-2.6.32-20-pve: 2.6.32-100
lvm2: 2.02.95-pve3
clvm: 2.02.95-pve3
corosync-pve: 1.4.5-1
openais-pve: 1.1.4-3
libqb0: 0.11.1-2
redhat-cluster-pve: 3.2.0-2
resource-agents-pve: 3.9.2-4
fence-agents-pve: 4.0.0-1
pve-cluster: 3.0-4
qemu-server: 3.0-15
pve-firmware: 1.0-22
libpve-common-perl: 3.0-4
libpve-access-control: 3.0-4
libpve-storage-perl: 3.0-6
vncterm: 1.1-3
vzctl: 4.0-1pve3
vzprocps: 2.0.11-2
vzquota: 3.1-2
pve-qemu-kvm: 1.4-12
ksm-control-daemon: 1.1-1


The goal is to locate a KVM template in RAM, and create in near realtime some new guests from this ramdisk template to get the best I/O.

Thanks a lot for your help

Best regards,

Smarteos


Thanks a lot for your help

 

[dietmar]

Try to use writeback cache settings for the disk.

 

[smarteos]

Try to use writeback cache settings for the disk.

Thank you so much Dietmar

It works perfectly now, and it's wonderfully fast ;-)

and associated with this new Kvm template function, it's a killing feature !!

Long life to your team

Best regards

Smarteos