3/26/2012 8:55:52 AM :: Queued for processing at 3/26/2012 8:55:52 AM
3/26/2012 8:55:52 AM :: Required resources have been assigned
3/26/2012 8:55:56 AM :: VM processing started at 3/26/2012 8:55:54 AM
3/26/2012 8:55:56 AM :: VM size: 90.0 GB (43.0 GB used)
3/26/2012 8:56:01 AM :: Using source proxy vbr-hq01.domain.local [hotadd;nbd]
3/26/2012 8:56:02 AM :: Using target proxy vbr-dc02.domain.local [hotadd;nbd]
3/26/2012 8:56:03 AM :: Discovering replica VM
3/26/2012 8:56:03 AM :: Preparing replica VM
3/26/2012 8:56:21 AM :: Preparing guest for hot backup
3/26/2012 8:56:24 AM :: Creating snapshot
3/26/2012 8:56:29 AM :: Releasing guest
3/26/2012 8:56:47 AM :: Processing configuration
3/26/2012 8:57:02 AM :: Creating helper snapshot
3/26/2012 8:57:11 AM :: Hard Disk 1 (50.0 GB)
3/26/2012 8:57:52 AM :: Hot add is not supported for this disk, failing over to network mode...
3/26/2012 8:58:06 AM :: Hard Disk 2 (20.0 GB)
3/26/2012 8:58:39 AM :: Hot add is not supported for this disk, failing over to network mode...
3/26/2012 8:58:52 AM :: Hard Disk 3 (10.0 GB)
3/26/2012 8:59:25 AM :: Hot add is not supported for this disk, failing over to network mode...
3/26/2012 8:59:31 AM :: Hard Disk 4 (10.0 GB)
3/26/2012 9:00:04 AM :: Hot add is not supported for this disk, failing over to network mode...
3/26/2012 9:00:12 AM :: Deleting helper snapshot
3/26/2012 9:01:13 AM :: Truncating transaction logs
3/26/2012 9:01:14 AM :: Removing snapshot
3/26/2012 9:02:01 AM :: Swap file blocks skipped: 13.5 MB
3/26/2012 9:02:01 AM :: Finalizing
3/26/2012 9:02:01 AM :: 1 restore point removed by retention policy
3/26/2012 9:02:37 AM :: Busy: Source 61% > Proxy 23% > Network 60% > Target 51%
3/26/2012 9:02:37 AM :: Primary bottleneck: Source
3/26/2012 9:02:37 AM :: Processing finished with warnings at 3/26/2012 9:02:37 AM
I assume the reason why you had these warning messages is that your backup job mode failed over to network mode because Virtual Appliance (Hot Add) mode was available. Anyway, you should have your backups in place, so there is nothing to worry about. Thanks!
Check out their backup mode used, I believe they didn't failover and were processed with a Virtual Appliance mode as it is selected by your backup proxy.
For virtual backup proxy servers it is always better to use Virtual Appliance mode, as it gives you better performance for the backup/replication jobs. However please be aware that for some VMs it will not be possible to use this mode, that is why these VMs will be processed in network mode and again there is nothing to worry about.
If Virtual Appliance mode fails to process some of your VMs and fails over to network mode, click here to see the complete list of current vStorage API limitation around Virtual Appliance.