How many hosts on each cluster?

[amiryala]

We are running 14 hosts in one cluster and want to fire up 18 more hosts. Best practices suggest that for VSphere 4.x, 8 hosts per a cluster (HA doesn't work between clusters) but it also says, 32 hosts per cluster will also work fine(some limitations). We are running 200 servers (Virtual Machines) on all the hosts. Now, I'm in a dilemma which one to go with.

Please help me.

[IMKrishna]

Have a look at This links:

http://www.yellow-bricks.com/2009/05/25/max-amount-of-vms-per-host/

http://www.yellow-bricks.com/vmware-high-availability-deepdiv/

Krishna

[Mauro Bonder]

the currenty maximum configurations supports 32 hosts per cluster you can validade it www.vmware.com/pdf/vsphere4/r41/vsp_41_config_max.pdf

[IMKrishna]

Yah, it can support 32 Hosts. But if you put more than 8 hosts in cluster, maximum number of vm's running on hosts limited to 40.

Krishna

[opbz]

You can put 32 hosts per cluster.

obviously when you go that high you can change the number of HA concurrent failover number.

seriously suggest you use esx4.1  it has inreased the time betwen hosts updates to 10sec (used to be every second) that reduces the traffic significantly.

Also the first 5 hosts you add are your HA primary ones .You need to ensure that if you are using blades that they are not all in the same chassis (again best practices) you can promote other servers to primary or configure them to be primary if you want but doing it this way is easy enough.

if you are using ESX (rather than ESXiyou should also increase the service console memory to the max. Finally ensure you do not mix ESX and ESXi servers in same cluster.. works fine for HA but can't really vmotion between them as the vmkernel is diferent enough..

by the way there is a new book HA rs deepdive that is VERY good and goes in detail over all the gory details about HA and DRs

good luck

[ArvindChaudhar1]

Dear Amiryala,

Its true you can go ahead with max 32 hots in one cluster, but do not go for maximum... pls verify the resource requirement of your servers(VMs) and compare with the availibility of resources of ESX Host(Physical Server), then design how much failover you are expacting along with some spare resources in each host. then calculate Total no of host required for your cluster.

-Arvind