Hello
I have some service (web for example), that i want to cluster (active/passive). I have two esx in two different location on two different datastore. I want to set up a apache cluster between two linux machines (centos) on different datastore.

this is not clustering, just HA. two different locations would suggest different subnets, therefore you'd need to be looking at changing your DNS entries for this, not actually anything on the machines themselves. DNS HA is generally pretty sucky. You could look at mechanisms to use http proxies (which themselves could be apache) to do failover to the servers behind, and those two proxies would then both be the target of DNS A records, however if one of those proxies fail you're still no better off...

Hmm, i mean i was looking into different types of hearbeat solution.

Well if you think that is the solution you may want to provide some useful information about the environment you're working with.

As acid_kewpie already mentioned you most likely can't do anything with clustering. Since you mentioned having these servers in two different physical locations this most likely means different IPs (unless you have a reliable means of transit between the two sites). As already mentioned you will then run into problems with DNS. I think the best you could hope for is using something to do regular server checks, and initiate a DNS change if the primary server is down.

Now the problem you can have with this is the time it will take for DNS changes to replicate through the world, and users hitting the down server until you update.