We have a VMWare ESXi 4.1 server hosting a number of Linux and Windows guests. Recently a new Linux guest was added to this server and seemed to be performing well. Tomcat and some other applications on this server were then installed which seem to have caused the server to run really slowly without any obvious resource issues.

Slow performance include:

• The time taken to bring up the password prompt over ssh takes a few seconds when it was previously instantaneous.
• The time taken to unzip a zip file which was previously a few seconds now takes around 30 seconds
• The time taken to compile vmware tools has increased by similar factors

Both the VMWare console and monitoring commands don't report any issues with high CPU or memory usage but something is obviously slowing the server down somehow.

Does anyone have any ideas what may be causing this issue and how it can be resolved?

Thanks,

Tom

Edit

As per your questions I’ve looked at some of the performance indicators on both the VM host and VM guest indicated.

Firstly I tried reserving the full amount of memory (3gb) for this VM – no other machines on this server have any memory reservation.

The swap in rate and swap out rate for the VM host and guest are now both zero.

Balloon memory on the guest is zero and on the host is 3.5gb (total memory on the host is 12gb)

The swap rate for the guest is also zero.

Swap used by the host is 200mb on average.

Compression and decompression rates for the host and guest are zero.

Command aborts for the host are zero.

Read latency is very low – maximum 10ms average 0.8ms.

Write latency is higher – a few spikes to 170ms but mostly around 25ms – is this bad?

Queue command latency is zero .

Physical disk read latency averages 5ms but often 10ms

Physical disk write latency averages 15ms but is often 20ms

I hope this helps - let me know if you need any more information.