[ClusterLabs] Preventing multiple resources from moving at the same time.

[Matthew Schumacher]

On 4/21/21 10:21 AM, Andrei Borzenkov wrote:
>> If I set the stickiness to 100 then it's a race condition, many times we
>> get the storage layer migrated without VirtualDomain noticing, but if
>> the stickiness is not set, then moving a resource causes the cluster to
>> re-balance and will cause the VM to fail every time because validation
>> is one of the first things we do when we migrate the VM, and it's at the
>> same time as a IP-ZFS-iSCSI move so the config file goes away for 5
>> seconds.
>>
>> I'm not sure how to fix this.  The nodes don't have local storage that
> Your nodes must have operating system and pacemaker stack loaded from
> somewhere before they can import zfs pool.

Yup, and they do.  There are plenty of ways to do this: internal SD 
card, usb boot, pxe boot, etc....  I prefer this because I don't need to 
maintain a boot drive, the nodes boot from the exact same image, and I 
have gobs of memory so the running system can run in a ramdisk.  This 
also makes it possible to boot my nodes with failed disks/controllers 
which makes troubleshooting easier.   I basically made a live CD distro 
that has everything I need.

>> I suppose the next step is to see if NFS has some sort of retry mode so
> That is what "hard" mount option is for.
>
Thanks, I'll take a look.

Matt