[SOLVED] qm importdisk kills my SAN

[Hannes Ylä-Jääski]

Hi!

I am migrating from XenServer to PVE. When running qm importdisk with raw disk images on my node local disk it kills my SAN connection. Which is 10GBit/s fibre multipath scsi to Fujitsu Eternus SAN. Vms shows sda: abort (with virtio_scsi) and some SATA emulated vms show i/o error and things goes bad.

EDIT: To clarify raw image sits on my nodes local disk and it is supposed to go to my storage which is located on SAN

Tried to run that import with ionice -c3 but did not much help..

Any ideas why qm importdisk is taking SO MUCH bandwith and kills all my vms?

 

[LnxBil]

How did you connect your VMs to your storage? Are you using LVM?

 

[Hannes Ylä-Jääski]

Yes. I am using lvm-thin on top of iscsi pvs..

 

[Hannes Ylä-Jääski]

Oh.. qm importdisk spawns qemu-img process.. I tried ionice -c3 for qm command.. maybe I should ionice that qemu-img instead..

 

[LnxBil]

Yes. I am using lvm-thin on top of iscsi pvs..

So, you're using a SAN with only one machine or are you planning to create a cluster?

 

[Hannes Ylä-Jääski]

So, you're using a SAN with only one machine or are you planning to create a cluster?

I am planning to run these kn cluster. I have lots of xen nodes in cluster and i am going to migrate them all to pve.

 

[dcsapak]

I am planning to run these kn cluster. I have lots of xen nodes in cluster and i am going to migrate them all to pve.

Yes. I am using lvm-thin on top of iscsi pvs..

you cannot use lvm-thin in a shared manner, this will not work and destroy your data

if you want to use a shared scsi use normal LVM

 

[LnxBil]

you cannot use lvm-thin in a shared manner, this will not work and destroy your data

if you want to use a shared scsi use normal LVM

That's why I asked :-D

There are a lot of settings you can tweak to optimize iSCSI, offloading, jumbo frames, multipathing, etc. ... the best one I always use is not to use iSCSI at all. I've never had I/O timeouts with FC-based environments.

 

[Hannes Ylä-Jääski]

Oh nice to hear now that I cannot use it in shared manner.. well i'll create new LVM pool for that then. I managed to figure this out by wrapping qemu-img into ionice -c2 shell script. Now it does not kill my SAN connection. Thanks for this information and I will use normal LVM when creating bigger data pools for the upcoming cluster.

Have to say that when using now PVE at work and at home it is far best virtualization environment I've ever used. Compared to XenServer its like day and night. Thanks for this support and this awesome software! Marking as solved.