vmware srm – replicating over a wan – optimizations

I’ve been working through a SRM setup and have been looking at ways to optimize the amount of traffic that is sent over the WAN. The first obvious move is to move your vmware swap files off the replicated LUNS.

Another way is to reduce the sync window. i.e. how often is yoru replication technology trying to keep the source and destination in sync? — Increasing this window can sometimes help you out. But that all depends on your delta’s.

For example – In the case of a windows page file on an active server (SQL etc) it could “potentially” change the whole file within an hour. If your replication was set to every hour and the page file was 4gb then you’d be sending at least 4gb every hour. Changing the sync on your replicated LUN to 8hrs instead would mean you’d only send the 4gb of “delta” (i.e. blocks that have changed since original snap)

Problem is that you would typically want to sync your virtual machines on a more frequent schedule than 8hrs. So this is where you need to move your windows page files onto a separate LUN (also replicated), but on a larger sync window (perhaps only once if your servers are static).