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September 10th, 2016 02:00
What should be the minimum size of each journal volume, if distributed consistency group is used?
We are using Recoverpoint/EX between 3 sites. Production and 1st DR is configured as synchronous and 2nd DR will be using asynchronous mode of replication. We are planning to use distributed consistency group. From documentation, I can find that Journal size for Distributed Consistency should be minimum 40 GB of size. Does it mean that, total journal size should be of minimum 40 GB? or Each volume assigned as Journal should be minimum 40 GB of size? Please someone clarify.
Thanks in advance.
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echolaughmk
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September 10th, 2016 05:00
Hi,
The 40gb journal size is the minimum per copy...this can be a single lun or multiple luns that add up to at least 40gb. This is the minimum per copy, however to answer your other question on what the sizes should be, this will depend on the write change rate of what you are replicating and the protection window you require per CG. The rule of thumb is about 15-20% of the total amount of data being replicated. For example, if one of your DCGs has a production server with LUNs totaling 500gb, then the journal per copy would be about 100gb following this rule. This could change and be more or less depending on how larger you want the protection window, but this is where most people start and then monitor. You can add volumes to the journal on the fly but you can't shrink it without losing the journal.
So in a nutshell, you need at least 40gb per copy, but yoy can use the rule of thumb or trial and error to tweak it as needed for your requirements keeping the minimum to at least 40gb.
Hth,
-keith