QUESTION: When building a SAN, what are the DR considerations? Do you need a separate SAN for DR or a NAS?
ANSWER: It is very important to know what kind of data will be stored on the SAN. Is it mission-critical, in that it must be available 100% of the time? Or can it be backed up to remote tape, since it doesn't need to be recovered quickly? Should it be mirrored or use data replication? Key questions to ask should be: what is your recovery time objective? What kind of data is stored on the SAN or NAS? How much money do you have for DR? (Cost will be a huge factor if you need to create a secondary site that is mirrored with the same hardware and software profiles). You don't necessarily need a separate DR SAN or NAS but you do need to have compatible site equipment so that when you back up to a secondary site, the data is available and can be recovered when there is a failure. In a number of cases, this will mean having a separate storage network at the second site for SAN and NAS that uses the same vendors.