The size of LUNs needed for reserved Lun pool for mirroring on EMC VNX

We are going to be mirroring about 14 Luns from one san to another.
The largest lun is 1925GB and the smallest is 200GB. The other luns are all different sizes in between the 1925GB and the 200GB.
So my question is, do I take 20% of the largest lun which is 1925Gb, which comes out to 385GB and then make all 14 reserved luns that size, 385GB on both the primary and the secondary?
Is this correct?
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vmichAsked:
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Mr TorturSystem EngineerCommented:
Hi,
AFAIK you need to have exactly the same LUN size between primary and secondary.
Why are you speaking about 20 % ?
What are you using for mirroring, mirroview I suppose ?

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vmichAuthor Commented:
yes mirrorview and all the docs stat to use 20% as a rule of thumb..
So if I have 10 4TB luns on the primary san then I have to also setup 10 4TB luns on the secondary san?
Then once that is setup, then I have to create the reserved luns for each Lun correct?
Mr TorturSystem EngineerCommented:
Yes, but again as far as I know.
I am used to VNX but not to mirroring or replicating them sadly.
Going to have a look at these 20%, wait a little please.
is this Asynchronous ?
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vmichAuthor Commented:
yes it is Asynchronous
Mr TorturSystem EngineerCommented:
Could you have a look at this ?
https://community.emc.com/message/565687

it seems, and that is somehow speaking to me from old courses, that 20% value is about the RLP LUN size, RLP standing for Reserved Lun Pool as cache volume or something like that used by Mirrorview.

Another URL :
http://www.penguinpunk.net/blog/reserved-lun-pool-with-emc-mirrorviewasynchronous/
Duncan MeyersCommented:
You need a minimum of 28 reserve LUNs (14 for each storage processor, two for each LUN that you're replicating). Make them 50GB each abd half are assigned to SPA and half to SPB. Monitor replication. If you have good bandwidth between the sites, the RLP will hardly get touched. On the other hand, if you have low bandwidth and a large rate of change, you may need to add some more reserve LUNs. MirrorView will take a reserve LUN for each LUN that's being replicated. It will use more LUNs if a reserved LUN fills with data waiting to be replicated.
vmichAuthor Commented:
so I was told now that you don't need Reserve luns for doing mirroring.. Is that true or not?
Duncan MeyersCommented:
For synchronous mirrors, that's correct  - you don't. For asynchronous mirrors, yes you do. The RLP (Reserve LUN Pool) is use to track changing data. See page 40 of this document: https://www.emc.com/collateral/hardware/white-papers/h2417-mirrorview-know-cx-series-flare-wp-ldv.pdf

As I said earlier, if you've got reasonable WAN bandwidth, you won't need to commit a lot of space to the RLP, but you will need some. If the WAN bandwidth is inadequate, you'll need more space in the RLP
vmichAuthor Commented:
Duncan,
Do I have to setup a connection between the 2 san units before I am able to add a secondary image?
Right now when I go into data protection and then click on manage mirror connections, there is nothing showing up on the pri or sec san. Is there a doc or steps thatI can follow to set this up?
vmichAuthor Commented:
How do I setup the mirrored connections between the 2 vnx san units?
I can ping both units from each other but I don't see anything when I click on manage mirror connections in unisphere..
Duncan MeyersCommented:
The two arrays have to be in the same domain. Note that we're talking about a Unisphere security domain, not an Active Directory domain. Instructions here: http://www.techrantz.com/2012/03/managing-storage-domains-in-unisphere.html. Once you've done that, you can run the MirrorView Wizard to set up the relationship. Go to Unisphere>Data Protection>MirrorView Wizard and run the wizard. Then you should be good to go.
vmichAuthor Commented:
20 %
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