I have a fairly old server, but it doesnt do much. Just a test lab at home. Its a HP DL380 G3 server, dual 3.2Ghz and 12GB RAM, installed vmware ESX 3.5.
Now I have 6 Windows 2003/2008 hosts on it, I have set memory for all to be 4GB each, but they dont all come on at thesame time. When I had 3 hosts, the performance was acceptable, but although saying this the RAID array was built on a raid 0. Now that I have rebuilt the array on a RAID 5, and added 3 extra hosts, I am not sure if its the IO that is slow or just the fact that i am no way a VM ware expert and just someone learning on the job.
I have started to read about vmware best practices, but I want to share my problem with others, I have seen things around memory/cpu reservation etc, I dont think I have done any of that. Also the physical server has 12GB RAM, but i find that i still have vswap files of 4GB each, this makes me to believe that its using the disk swap files as memory for the VM hosts, pls correct me if i am wrong. What i want to know is, what is happenning to all the 12GB RAM on the server itself.
Thanks in advance.
vmware supports memory over commit, memory ballooning, compression and transparent page sharing. yes the vswap size = the number of memory you assigned to the virtual machine. if you have raid5, then the raid penalty would be 4 hence it's would be slower than raid 0. to know whether it can cater the needs of additional 3 hosts really depends on how heavy your virtual machine on the disk IOPS. http://www.yellow-bricks.com/2009/12/23/iops/