Tape Backup Rides Shotgun

In one key regard, retooling your storage infrastructure is a lot like walking into a Wild West gunfight at high noon. In either scenario, it's reassuring to know that someone is watching your back. And, it's doubly reassuring to know that the person who has you covered is not some tenderfoot who might turn yellow at the first sign of danger. On the not-so-dusty streets of a corporate data center or disaster recovery facility, that steady, experienced backup comes from, well, the backup - tape backup, that is.

You need your tape backup system to remain focused on reliable back end protection. But, you also need the vendors who provide that protection at the back to know something about the view from the middle of main street - the corporate LAN or WAN (wide area network), where storage devices confront applications and users. That's why it is perhaps triply reassuring to know that SAN (storage area network) management software developers aren't the only ones worrying about how you're going to manage your stored assets. So are the suppliers of tape media, drives, and automated libraries.

Tape Joins Software For Business Continuity
Mention storage these days, and tape backup providers are just as likely to mention storage virtualization as they are to discuss capacity and throughput. Consider the following comment from Pete Koliopoulos, director of product marketing for ATS (automated tape solutions) at StorageTek (Louisville, CO): "We show our customers how storage management tools can help them keep more data available without going to tape retrieval. That way they can get their data faster and with less hassle. Virtualization tools allow customers to manage and reconfigure the back end without touching the front end." Koliopoulos clearly knows that, under the harsh glare of a midday showdown with a potential systems failure, companies want to be able to reload in a hurry. (A quick primer: Virtualization refers to the software's ability to ignore physical differences in storage hardware and media. That allows data to be assigned to and retrieved from logical units and partitions across various kinds of storage devices, thus eliminating an application's or user's need to know which particular device is currently housing which particular data.)

Echoing Koliopoulos regarding the importance of management strategies is Bob Covey, VP, marketing, for tape library specialist Qualstar Corp. (Simi Valley, CA). He points to scaling as representative of the evolution of storage management. "There are no real physical or mechanical limitations to tape libraries when it comes to scaling up in capacity. There are libraries out there now that can hold 50,000 tapes," Covey explains. "Traditionally, scaling has been done primarily by mechanically bolting additional modules into a single library. But, the emerging way is to use storage management software to virtualize libraries that house different tape technologies."

Of course, post-9/11 anxieties about business continuity have accelerated concerns about retrieving more than just data. "We're in the data recapture business, but we're hearing more and more about the need to restore the system to its pre-loss status," admits Bill Reed, VP, marketing and business development, Spectra Logic Corp. (Boulder, CO). "In addition to having offline copies of their data, companies now want to back up the state their applications were in at any point in time. They want to know what the disk partitions looked like and what users' passwords were in effect at the moment the system went down. So, tape backup is one part of a business continuity strategy."

Tape Partners With Disk For Staged Backup
In a non-disaster situation (i.e. during normal day-to-day operations), business continuity still involves recovering data as fast as possible. Disk crashes, momentary systems lockups, and the like often force the need to quickly retrieve a second copy of key data. For that purpose, mirroring on magnetic drives - for example, in a RAID (redundant array of independent disks) configuration - is effective. However, it can also be expensive, particularly if it is used to keep days' or weeks' worth of data. Many companies are, instead, using it for staged backup, in which data is consistently copied from disk to disk before being backed up to tape in fairly frequent intervals - say, daily, twice daily, or hourly.

Moving a copy of data to secondary online storage before moving it to tape ensures quick retrieval of the most recent data (not yet backed up to tape). It also provides a temporary, second layer "vault" from which to move data to tape without the need for lengthy, systems-interrupting backup windows. Says Reed, "The greatest need for restore generally occurs very soon after the initial storing. Even if you limit yourself to keeping only 24 hours' worth of data in snapshot form with online availability, you're going to answer most users' needs. Then you can move it off to tape and free up that disk space for the next snapshot. Backing up the snapshot copy rather than the primary online copy makes the process essentially windowless."

Of course, not all companies can afford, nor may they even need, staged backup using a preliminary disk to disk step. Nonetheless, all three vendor representatives agree that each new generation of tape technology - whether it be media, drive, or library - offers increased capacity and throughput for attacking backup duration. However, Koliopoulos offers a final word of caution when it comes to users' expectations. "Customers need to realize that increasing backup performance doesn't necessarily shrink the backup window proportionally. They might expect that doubling performance will cut the window by half," he says. "But that number doesn't necessarily stay constant because the company may have brought on new applications, increased the amount of servers it is backing up, or begun to back up more often in order to capture snapshots."