Can anyone give me some insight on what is a good rule of thumb for the number of virtual machines per ESX host in a farm? On top of that I am also wondering what limits should be observed as to when your CPU and Memory use should be considered at its maximum.
We have (4) Dell R900 servers with 4 quad core procs in aeach and a 128GB of memory. We currently have around 45 vm's per host and the CPU and memory use hangs around the 40-50% range.
Any advice would be appreciated.
Can anyone give me some insight on what is a good rule of thumb for the number of virtual machines per ESX host in a farm?
Depends on core type, how many. but the REAL difference is the DISK. CPU and Memory is irrelevant, DISK is most important.
Quad core can do 8 vCPU PER core (as a rule) which means VM's with a SINGLE CPU. Memory of course is a limit which you can easily identify. Six core processors (R910/R710) can do around 12-16 VM's PER core, same memory and CPU, but spindle count is the ultimate dependence.
SAS/SCSI is better than SATA, SATA MAY be OK for a few VM's but if you want performance go SAS/SCSI.
Yes I agree that disk is important as we are getting ready to replace our entire SAN. But there si only so much CPU and memory capacity from a ohysical standpoint on our ESX hosts. Currently all four hosts are around the 50% mark. My question is how high can that get before a new host should get added to the cluster.
My question is how high can that get before a new host should get added to the cluster.
Well you don't want it to go above 90%, actually 80% for cushion.. Otherwise your host will begin to swap, that's bad.
So if you see memory getting around 80% consistently, it may be time to add a new host.