Add Hard Disk "Storage Selector" times out

[cdukes]

I am having difficulty when adding a new disk to a vm where the storage selector dropdown is timing out. I assume this is from I/O degradation so the dropdown can't get the list of available NFS or iSCI mounts.
But I can't ascertain the cause.
The NAS is connected via quad gigabit bond and the current network utilization on that interface is < 100Mbps.
This is on pve-manager/4.3-1/e7cdc165 (running kernel: 4.4.19-1-pve) using a two-server cluster. If I move the VM to the other server, it exhibits the same behavior.
My "guess" is this is some performance issue with NFS, but I don't know where to look to find out.

Also, not sure if this is related, but I happened to leave an ssh session open last night and had this on one of the servers this morning:

Broadcast message from systemd-journald@ucs (Wed 2016-10-26 00:17:23 EDT):
iscsid[2042]:
Message from syslogd@ucs at Oct 26 00:17:23 ...
iscsid:
Broadcast message from systemd-journald@ucs (Wed 2016-10-26 05:46:18 EDT):
iscsid[2042]:
Message from syslogd@ucs at Oct 26 05:46:18 ...
iscsid:

Quite an odd message (no message at all, just "iscid:").

 

[wolfgang]

Hi,

your correct this behavior occurs when a storage is hanging.
You can check this if you go on the GUI and see the storage summary if it makes trouble you get a notification on this view.

 

[cdukes]

You can check this if you go on the GUI and see the storage summary if it makes trouble you get a notification on this view.

It was hanging for both NFS and iSCI when I checked.
Because of that console message earlier about iSCI, I tried removing the iSCI from the system and now it works as expected.
The odd thing here is that both NFS and iSCI are connected to the same NAS server (Synology RS3617xs)