I have been running an ESXi 4.0 server for months with a couple of WinServer2003 and several Ubuntu Server 10.4 VMs. The performance has been impressive on 6GB i7 Asus P6T hardware.
Suddenly, a week ago, ssh logins to the Ubuntu VMs take 10 minutes when connecting over the LAN (over a WAN the connection (pipe) is broken long before that). When logging in to these VMs the password prompt arrives immediately, and failed passwords are responded to immediately.
But the moment I log in then the shell prompt appears and I hang for many minutes. Sometimes the connection hangs before the shell prompt appears and sometimes I can type in a command but the moment I hit return the machine hangs. 10 full minute later control returns and the VM is responsive.
NOTE: there are several Ubuntu VMs on the same host machine that are identical in all ways that I can tell. However, only one of the VMs displays this behavior. That is why I mention the ESXi host in passing - I don't think it has anything to do with the problem.
This behavior is never seen when I connect with the troubled-VM's console (through vSphere Client). From the console the Ubuntu VMs all respond beautifully.
I have seen: http://kb.vmware.com/selfservice/microsites/search.do?cmd=displayKC&docType=kc&externalId=1003496&sliceId=1&docTypeID=DT_KB_1_1&dialogID=229586372&stateId=1%200%20229588522 ...and since that relates to delays in seeing the password prompt that does not appear to be the solution here.
Any other suggestions very welcome - thank you.