In-Depth
In the Tape vs. Disk War, Think Tape AND Disk
Here's a simple solution to the disk vs. tape debate: use the technologies together and get the best of both worlds.
By Mark Ferelli
As data protection becomes a growing part of the IT budget, it seems like every technology that records data wants to claim primacy and indispensability. Too frequently in the frantic dash for market share, technology that has stood the test of time is falsely accused of being hopelessly out of date. So it is with magnetic tape in the data center. The veteran technology is inaccurately identified as "yesterday's technology." Tape technology is experiencing a Renaissance; a rebirth based on the growing recognition that tape technology is responding regularly and reliably to today's vital business requirements.
Companies across all industries and of all sizes are looking for reliable solutions to protect the data and assure that it is readily retrievable.
Naturally, the first step is for IT to commit to data management. This includes management of the data itself, the software resources and the hardware resources. Best practices in data classification, metadata management, capacity utilization, and similar disciplines help IT managers grow into tightly integrated storage resource managers.
Analysts and disk vendors have been challenging the use of tape in the data center. A recurring death knell has been rung for tape technology, only to be repeatedly proven false. Contrary to frequent predictions, disk technology has not swept the backup and archiving IT markets. Those who condemn tape as "yesterday's technology" are reciting yesterday's marketing messages from competing technologies. When it comes to a full-featured hardware data protection strategy, the focus should be on disk and tape, not disk or tape.
Tiering Storage
Storage administrators understand that a large part of corporate data is accessed infrequently. Yet storage volumes are multiplying each year as corporations generate more electronic content and struggle to meet complex business transactions, regulatory compliance mandates, and e-discovery requirements. Expanding storage on the storage area network (SAN) simply by adding expensive Fibre Channel (FC) disks is typically not a cost-efficient option. By implementing a tiered storage architecture, an IT organization can dramatically improve storage capacities, manage storage costs, and improve performance.
The lure of added capacity is compelling; a 1 TB SATA hard drive costs far less than a 146 GB FC drive. When multiplied out over dozens, hundreds, and even thousands of drives, the added storage and lower disk cost can be substantial. Administrators can then further reduce costs by migrating reference data onto tape, which is cost efficient, reliable, and removable. Although tape cannot match the access time of high-end FC disks, businesses may realistically translate tiers of storage as "tiers of service," offering storage users an appropriate level of reliability, accessibility, and performance at each level.
Overall storage performance can benefit from tiered storage. With all data on a single hard disk tier, the effort to access stored data can slow performance to a crawl. That problem is eased once storage is reorganized into tiers across two or more storage subsystems. The reduction in performance speed is offset by the reduction in competition for data access. Furthermore, a secondary tape tier reduces the number of data requests arriving at the first tier, allowing faster access at that first tier.
Tape as a tier-2 solution for backup and archival is now popular for backup, but it is less useful for long-term archives of reference information.