Merging two SANs in to one larger SAN

[dayoung]

Currently I have two SAN's in two different data centers.  SAN A is in one data center that does NOT have generator power so is always susceptible to power issues.  SAN B is in a data center in another building less then 1/2 mile away but does have generator power so having power outages really isn't an issue. 

We are contemplating moving some storage devices from the SAN A data center to the SAN B data center so in the event we have power issues in the SAN A data center at least the storage devices that are sitting in the other data center would not be affected.

So in order to do this we'd need to connect the two SAN's so we'd essentially have one big SAN between two data centers.  I do not have any experience doing this so wondering if there is some documenation somewhere that lays out what needs to be done.  A couple questions I have.

1) Will I need any additional hardware?  Currently the SAN's in each building use 2499-384? (or 768?) switches.  Do I need anything additional at each end?

2) Will an ISL link between the two switches be the only thing required assuming we currently have some fiber channel connectivity between the two data centers?

And of course we won't want any performance degradation :-)

Any thoughts or guidlines/documenation would be appreciated.

Thanks.

[alexey.stepanov]

The distance is not that long, so if your combined SAN wouldn't break any domain/port/wwn/npiv/whatever else count limits, then you are good to just join two SANs together.
Make sure your links between the buildings are single mode, and prepare the suitable number of long wave SFPs.
Merging two live fabrics is a task in itself, especially if you want to do it without any interruptions. You'll need to do some preparation work for it, i.e. make all domain IDs unique, check the compatibility of all the fabric wide and ISL parameters etc... And also prepare and activate the merged zoning config.