First, there is no rule or best practice that says the source and target arrays must have the same Reserve LUN Pool configuration.  Sizing an RLP is dependent on the workload of the one array that RLP is servicing.  That said, you should calculate the proper RLP sizing for the source and target independently from each other.  They may have very similar results, they may not.  For example, if the source array is a Mirrorview/A Source with NO Snaps, but the Mirrorview/A target is also using snaps, the RLP on the target array will likely need to be larger.  Generally, EMC recommends picking an average sized LUN size for the pool using a % of the size of the LUNs you are replicating.   So if your production data is on LUNs ranging in size from 100-500GB in size, then calculate 10% of the largest LUN sized (50GB) and use that as the individual LUN size.  Then calculate the amount of data changed during the lifetime of a snapshot (Mirrorview/A creates a special version of snap for each update) and ensure that the total size of all LUNs in the RLP can handle that change rate.  There are a couple of other rules...  1.) You need to have, at a minimum, 1 RLP LUN per replicated or snapped LUN.  If you are replicating 5 LUNs, your RLP MUST have at least 5 LUNs.  When a snapshot is created (or an MV/A session starts) Snapview/MirrorView will grab one LUN from the RLP to track changes for the production LUN.  You can have multiple snaps against the same production LUN and they will all share the same RLP LUN until it fills up, at which time another RLP LUN will be allocated.  2.) Each array has a maximum for number of LUNs in the RLP, if your change rate is high, you may hit the maximum # of LUNs and still need more space.  If this occurs, use fewer/larger LUNs in the RLP.  When I first started using MV/A a long time ago we sized the RLP with 15GB LUNs and as we grew we maxed out the LUN count.  I then configured the RLP using 30GB LUNs and that solved the problem.  Since the remote DR array was a different model, with lower LUN count limits in the RLP, it had larger RLP LUNs, and we had more overall space in the RLP at the target side since we wanted to leave snaps running for longer periods of time during the DR test.
Hi All,  Background Information:  We have two SAN sites.  Source and Target.  Were using Mirrorview/Asynchronous.  When I first set things up about 6 months ago, I made about 30 5GB Luns at each site for RLP.  Then about a week ago the target sites RLP's all filled up.  I kept adding more and they kept filling up.  I contacted EMC and they advised me my RLP's were too small for the LUNS and the LUN sizes at my source site.  So I started creatig 50GB LUNS and began adding them to the RLP at the target.  I also changed my "update type" from 0 to 10.  This fixed the problem.  Now finally, here is my question.  Now that my RLP is significantly larger, do I also need to change my RLP's at the source?  They are still 5GB LUNS vice the 50GB LUNS that are at the target.  What is best practice?  Thank you.
Configuring Reserver LUN Pools (RLP's)