My analysis of the failure leads me to think that it was caused by there being too many disks attached via Hot Add to my Veeam backup server.Unable to allocate processing resources. Error: Collection was modified; enumeration operation may not execute.
My VBR server is a VM with one (1) HDD C: on SCSI 0:0 and three (3) HDDs on a separate controller SCSI 1:0 1:1 and 1:2
At the time of failure I had a VM with four (4) HDDs being backed up, plus another two VMs each with two (2) HDDs queued up. So I interpret that as possibly:
1 disk C: on the VBR server
4 disks via Hot Add for VM being backed up
2 disks in the queue for additional VM backup
2 disks in the queue for another VM backup
totalling 9 ... more than that 8 allowed. Is this analysis likely to be correct? Is it possible for me to add another SCSI controller to the VBR server and then force VBR to use that controller for the HotAdd tasks?