[Pacemaker] KVM live migration and multipath

[Sven Arnold]

Hi,

>> I did not trigger file system corruptions again. So, at this moment it
>> looks like it is important to:
>> - turn caching off
>> - use native aio
>> - *and* use an up-to-date machine type
>>
>> Failure to meet any of these criteria would result in fs corruption.
>> Does this make sense at all?
>
> Later part is a little bit surprising. You may want to look at qemu
> sources to see what are the differences between that machine versions,
> they all are in one file, and well organized. Usually differences are
> not so big, but I wouldn't say they may not affect what you observe.
>

Thanks for the pointer. I will see if I can get some additional insight 
there.


>> Do you manage the multipath daemon with pacemaker? In my setup multipath
>> is started at boot time and not managed by pacemaker.
>
> Yes. And all multipath records as well. That is the part of my iscsi RA.

Ah, you are using your own RA? Is this one public?
I use lsb:open-iscsi since it looked to me that the included iscsi RA 
relies on the operating system to start the iscsi daemon and I wanted to 
avoid that.

>
> Wait. You do have targets and initiators on the same boxes, correct?
>
> But what is it for? I recall you have active/passive drbd there, and
> then export it with iSCSI, and then connect via iSCSI to the same host?
> Why just doesn't back VMs with DRBD?

Not exactly. I do have three nodes, two of them providing storage as 
active/passive drbd. I want to run several VMs on the same cluster that 
are distributed among the nodes.
In fact I currently have a setup where two of the VMs that need a bit 
more I/O are backed directly with DRBD. The drawback is that those can 
not be live migrated.

>
> Vladislav
>

Vladislav, thank you very much for you kind support. Your help was very 
much appreciated!

I am off now for vacation and after that will see if I can ensure that I 
have reached a stable setup. I guess there are some minor issues 
regarding dependencies and monitoring of some resources but this is 
another topic.

Best regards,

Sven