KVm Boot Vms with DRBD

[vitor costa]

I have some DRBD cluster (6 clusters). The Option START ON BOOT apear not work in Vms storaged in DRBD. Vms in local storage start at boot ok, but not the DRBD storage.

One cluster have 2 TB storage and another 500GB. After boot host,, i can log on and cat /proc/drbd show the DRBD resync process...take some time (2 - 3 minutes). I think KVM machins cant start while resync....

Are any way to program QEMU-SERVER to wait some minutes before load ? Or anther way to solve the question ?

 

[bohansen]

Seems like DRBD ressources are started later than qemu-server. Try changing the startup order. E.g. like this moving drbd to startup order 23 (qemu-server is 24 here):

update-rc.d -f drbd remove
update-rc.d drbd start 23 2 3 4 5 . stop 08 0 1 6 .

Best regards,
Bo

 

[vitor costa]

Tanks Bohanse, your solution works very nice.

Proxmox Team, is possible make this as default situation (in distro) ?

Another question:

- With this change the VMs boot when host boot, but the drbd sync process take 2-5 minutes with Vm already runing. The Sync Data will come from another node to node where VM is runing.. so if VM after boot start write data on virtual disc this will be colide situation ! or not ?

 

[dietmar]

Proxmox Team, is possible make this as default situation (in distro) ?

I am not sure if that change solves all problems. Instead, qemu-server should wait until DRBD is up and running.

 

[vitor costa]

Dietmar,

I think is needed a script in qemu-server start to check drbd is syncing,.. if is then wait... This script can test cat /proc/drbd for syncing word, waiting while found and continue when not found (if splitbrain or another condidion the syncing will desapear and the qemu start anyway).

 

[vitor costa]

I made this script:

while $flag; do

    result_dr=`grep -o Sync /proc/drbd`

    if [ $result_dr ]; then
        flag=true
    else
        flag=false
    fi
    sleep 3
done

Put in /usr/sbin , then insert a call in /etc/init.d/qemu-server:

case "$1" in
  start)
        (egrep '^flags.*svm' /proc/cpuinfo >/dev/null && modprobe -q kvm-amd) ||
        (egrep '^flags.*vmx' /proc/cpuinfo >/dev/null && modprobe -q kvm-intel) ||
        echo "unable to load kvm module"

        modprobe -q vhost_net || true
        /usr/sbin/wait-drbd
        $PROG startall
        ;;

All is working Now.