Replicated LUN size consideration using RC

[Rahul_Jindal]

Hello Team,

I am designing a solution for my company wherein we have two sites 40 km apart from each other. My solution includes 3PAR 7400 at each site and remote copy will be used to replicate the volumes for DR purpose.

What parameters should i consider while creating a baseline for replicated LUN sizes?

Regards,

Rahul

[Sheldon Smith]

For starters, the LUNs need to be large enough to hold the data that needs to be replicated! :)

One consideration would be how you are connecting the two sites: RCFC or RCIP, and what is the round-trip latency?

Assuming the latency is too long for a supported synchronous replication, then what is the minimum periodicity for each RC Group that would allow the Groups to complete their synchronizations before starting the next ones.

Lastly, how much needs to be initially replicated vs bandwidth? How long will it take to get the initial volume to the second site? You may need to read the Remote Copy User's Guide on the process to use an external medium (tape?) to initially synchronize the volume(s).

Note: While I work for HP, all of my comments (whether noted or not), are my own and are not any official representation of the company.
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[Rahul_Jindal]

Hi Sheldon,

We will be using RCFC. The distance between two sites is 25 miles and the bandwidth available is 6GB/s.

We will use async replication to replicate the data. Initial data which needs to be replicated will be around 20 TB.

The concern that i have is regarding LUN size of replicated volumes. If i define a LUN size baseline of 2GB each exported to VMware, will there be any challenge during replication. Apart from DS, i have ~ 30 RDM's with 10 TB each in size.

Regards,
Rahul

[Sheldon Smith]

The 3PAR array supports virtual volume sizes up to 16 TB.

The initial transfer will obviously take some time. Create the remote copy group with the desired synchronization period, start the group. Check the task details for the remote copy group.

There are web sites with bandwidth calculators to help give you an idea of how long the initial copy will take.