Storage Area Networks For Dummies®

Chapter 6: SANs and Disaster Recovery
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✓ It’s great for legacy servers and mainframes.
✓ It offers some arrays (HDS Tagmastore) that can virtualize cheaper storage
to be used as target storage for the DR site, which helps minimize
costs for mainframe DR.
✓ It includes specialized functionality for mainframe environments.
✓ It can connect to FICON and ESCON equipment (mainframe stuff).
The disadvantages of an array-based solution follow:
✓ It usually requires the same hardware at both locations from the same
vendor.
✓ It can be very complex and expensive to implement and manage.
✓ It has very high bandwidth requirements.
✓ It usually cannot create consistency groups across storage arrays.
✓ It’s expensive to buy and maintain.
✓ It offers only limited application integration.
Choose an array-based solution when . . .
✓ You need to replicate mainframe or legacy data.
✓ You have deep pockets and want what the banks use.
✓ You expect to be standardizing on a single array vendor anyway.
✓ You need to replicate only a short distance, have plenty of bandwidth,
and want to use synchronous replication to avoid the chance of data loss.
✓ The proposed solution is cheaper than either host-based or appliancebased
replication.
Shipping tapes as a solution
The last method is to back up to tape and then ship the tapes offsite for
recovery. Companies without a SAN have shipped tapes to companies such
as Iron Mountain and SunGard for years. Shipping tapes can be cost-effective
to implement but does not provide the enhanced recovery time or recoverypoint
objectives gained from SAN-based data replication.
The advantages of shipping tapes follow:
✓ It’s usually cheaper than SAN-based replication.
✓ It doesn’t require a wide area network (WAN).