Accessing storage at different locations - design considerations

[Madura Malwatte]

I have a requirement where we need to connect two Data center rooms together via an ISL link between two MDS switches. The rooms may be more than 100m apart. Compute devices in one room will be accessing storage in the same room (directly connected to the MDS switch) and will also need to access storage (connected off the adjacent MDS) in the other room. Will this be an issue when the compute accesses storage in the same room compared to accessing in the other room? From experience how much latency would traffic going 1 hop and over an ISL link actually account for? Would the difference in access speed cause problems? Are there any studies I can refer to when designing access across inter-room storage, in particular when compute devices are accessing storage at different locations?

[Walter Dey]

Hi

I assume (hope) you have a dual fabric in each DC, meaning MDS A/B in DC1, and MDS C/D in DC2

You would then stretch the fabric across the 2 DC, e.g. having a ISL (or most likely ISL port channel) between A and C, resp. B and D. 

Of course, this can be done ! don't know if you synch mirror between the 2 DC ?

Latency isn't a problem, bandwidth/oversubscription has to be carefully designed.