New Twists in Tape Libraries

Posted on October 01, 1997

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New Twists in Tape Libraries

Check out some of the more recent innovations in the hottest segment of the tape automation market--DLT libraries.

Dave Simpson

Most storage integrators are aware of the key benefits of tape libraries: economies of scale, centralized storage and storage management, lights-out operation, data protection, and a reduction in the total cost of ownership. While still providing decent margins and follow-through sales opportunities for resellers, tape libraries at the end-user level have plummeted in some cases to mere pennies per megabyte--a big draw for today`s cost-conscious IT managers.

So, it`s no wonder that the tape library market is booming. And the fastest growing segment is DLT libraries. Freeman Associates, a storage market research firm in Santa Barbara, CA, estimates that the overall market for tape libraries is growing at a 26% annual rate, and DLT library shipments are surging at more than 33% per year.

Nevertheless, the perception at some IS shops is that "if you`ve seen one tape library, you`ve seen them all." Not so. In an attempt to differentiate themselves in an explosive-yet-crowded market, library manufacturers are adding a raft of nifty features that collectively could provide a number of benefits for IS managers, including increased ease of use and manageability, faster data access times for "near on-line" (as opposed to strictly backup) applications, and no-brainer scalability well into terabyte territory.

With demand so high, it`s no surprise that DLT library introductions are coming on almost a weekly basis. For example, Hewlett-Packard earlier this week announced major upgrades to its line of DLT libraries. Formerly available only with 20 GB (uncompressed) DLT 4000 drives and Fast/Narrow SCSI interfaces, HP`s SureStore libraries will be available in a couple months with 35 GB (uncompressed) DLT 7000 drives and Fast/Wide SCSI buses.

HP`s libraries, which are based on the company`s optical jukebox robotics mechanisms, come in 15-slot versions with one or two drives or in 28/48-slot versions with two or four drives. HP is expected to round out the low end of its DLT libraries in December with production shipments of the Autoloader 418, a one-drive eight-slot implementation.

Similarly, ADIC last week rounded out the low end of its DLT library line with a one-drive seven-tape autoloader. (Freeman Associates defines an autoloader as a single-drive mechanism; a library is a multiple-drive unit.) ADIC`s FastStor autoloader is primarily designed for users who are upgrading from standalone DLT drives.

At next month`s COMDEX extravaganza, Quantum--the sole manufacturer of DLT drives--will introduce a multi-drive DLT library. Shipments are expected by year-end.

At the high end of the DLT library market, Breece Hill is expected to show at COMDEX a huge library system that at least theoretically can scale to 1,680 cartridges--or 118 TB in compressed mode--in an eight-module configuration that`s linked via fault-tolerant pass-through mechanisms. Shipments are expected by the end of the year. Breece`s Saguaro system can be configured with 12-drive 70-cartridge libraries or in 9 x 140 or 6 x 210 versions. Saguaro will compete with high-end libraries from such vendors as ATL Products and tape library leader Storage Technology.

Scalability is also the name of the game at Overland Data. Users can stack as many as nine LibraryXpress modules in a Lego-like fashion for up to 3.36 TB of uncompressed capacity (6.72 TB with compression).

For the utmost in scalability, consider Emass` massive libraries, which can be configured with as many as 50,000 cartridges. Emass` "low-end" libraries, introduced earlier this year, hold 118 to 788 cartridges.

Users can mix virtually any type of tape technology (and, for that matter, optical technologies) in Emass` "mixed-media" libraries. For example, you could configure a library with a mix of IBM 3480/ 3490/3490E/3590 drives and cartridges or you could use the libraries for mass migrations from one tape technology to another.

Similarly, MediaLogic`s tape libraries include a "MixedMedia Interchange Drawer" that allows different tape technologies--or RAID subsystems--to be mixed in a single library. MediaLogic`s libraries come with one to five drives in a Ferris wheel-like carousel loading mechanism and redundant robotics, with one loader per drive. Potential advantages include faster load times, hot-swapping drives and/or DataPaks for off-line storage, and the ability to reassign drives in the event of a drive or robotics failure.

Web-based Management

On the software side, ATL is ahead of the DLT pack with its WebAdmin software. WebAdmin allows remote monitoring and configuration of libraries from standard Web browsers. (For more information on Web-based storage monitoring, see "Managing Storage over the Web," pp. 38-42.) Potential advantages include increased availability and time savings because administrators can receive failure alerts, detailed failure information, and remote diagnostics from centralized browser consoles.

For now, WebAdmin runs only on Solaris, but HP-UX and AIX versions are due later this month and an NT version is due early next year. WebAdmin is based on code developed by Veritas Software (see the sidebar "VML Takes the Sting out of Library Management").

Software is also a key differentiating factor at Exabyte, the developer of 8mm tape technology and a recent convert to DLT libraries. Like ATL, Exabyte is developing UNIX-based library management software, based on Veritas` VML code, that allows administrators to configure, monitor, and diagnose tape libraries remotely. For the Windows NT market, Exabyte is working with HighGround Systems to develop library management and automation software.

In another twist, ATL recently began shipping low-end DLT libraries equipped with standard PCI buses. The P1000 library is the first implementation under an umbrella architecture, dubbed Prism, that will eventually encompass ATL`s entire line of libraries. The advantage for storage integrators is the ability to easily upgrade to network-attached interfaces such as Fibre Channel, Ethernet, FDDI, and ATM.

Currently, there`s little demand for interfaces such as Fibre Channel in the tape library market, but demand is expected to pick up once Fibre Channel is deployed in mainstream disk-based applications. ADIC, for one, plans to introduce networking gear for Fibre Channel- to-SCSI attachment of tape libraries by year-end. Other DLT library manufacturers, such as Overland Data and Storage Technology, are also working on Fibre Channel attachments to their tape libraries. (For more information about Fibre Channel, see this month`s Cover Story.)

ATL has even more futuristic plans for its DLT libraries. In a move that may make tape libraries look more like RAID systems or clustered servers, ATL eventually plans to embed full-fledged servers inside its libraries. Potential advantages include resource sharing and load balancing across tape drives as well as tape-to-tape mirroring, copying, and archiving for disaster planning and recovery.

Tape Trends

All DLT library vendors tout superior speed, but in reality the speed of the robotics mechanism is fairly irrelevant in backup applications, which are by far the most common library applications. For backup, the transfer rate of the tape drive is the key performance criterion as IT shops try to backup more and more data in shrinking backup windows.

But as the speed of DLT drives--and other tape technologies such as Exabyte`s Mammoth, IBM`s Magstar, and Sony`s AIT--increases, libraries are being used more and more in near on-line applications. In these cases, data access times become critical. Fast data access times are a key advantage of technologies such as Magstar and AIT. Applications driving the trend toward near-online libraries include video, imaging, multimedia, Internet/ intranet servers, technical applications such as seismic analysis, and to a lesser degree, more conventional applications such as data warehousing and data mining.

Hierarchical storage management (HSM) is another application that benefits significantly from fast access times. HSM migrates files between disk drives and tape or optical devices based on a number of criteria, such as frequency of file use, age since last use, schedule date, disk utilization, and file type, ownership, and size.

Bear in mind, however, that overall performance may depend more on the speed of the host CPU, the disk-drive subsystem, and the I/O channel as well as on bus overhead and the performance of the operating system, file system, and applications software. Library management software is responsible for functions such as robotics control, queuing of user requests, control of media movement, management of data, and interface control.

Another trend in the tape library arena is toward rack-mountable designs. Vendors such as ADIC, Hewlett-Packard, and Quantum tout the small footprint and rack-mount capabilities of their libraries. For example, you can put two HP Autoloader 418 units in a single 19-inch rack. Size becomes increasingly important as IS shops try to centralize their storage devices and save expensive--and shrinking--floor space.

Yet another trend in the tape library market is embedding library management code into operating systems. Most of this action is taking place in the Windows NT market. Software vendors such as Microsoft, HighGround Systems, and Veritas Software are building into NT 5.0 a number of features that promise to make it much easier for administrators to manage libraries and other robotics mechanisms such as optical jukeboxes. However, many of these library management features won`t be available until Windows NT 5.0 arrives, and it`s anybody`s guess when that will be.

VML Takes the Sting out of Library Management

A key trend in the tape library market is a move toward more functionality in media management software. In the UNIX market, one of the leaders is Veritas Software, which released its Veritas Media Librarian code this summer. VML is licensed to OEMs, including ATL Products and Exabyte. Veritas is expected to announce other licensees in the next couple of months.

VML is a removable media management tool that allows a virtually unlimited number of users and applications to share access to distributed heterogeneous storage devices. Potential advantages include increased manageability, availability, media accessibility, as well as reduced management costs.

VML is currently compatible with Solaris, HP-UX, and AIX. An NT version is due next year. An NT version of VML would compete with media management software from HighGround Systems.

PicTel Relies on DLT

PictureTel is a worldwide leader in video conferencing. At the company`s Andover, MA, headquarters, the engineering group`s network supports about 400 workstations and more than 50 servers, all connected over a 100Base-T FDDI backbone with 10Base-T connections to the desktop. Most of the computers on the network are Sun systems.

Alan Silverman, a member of the technical support team for the engineering network, is responsible for backing up all of those systems. His solution? DLT libraries from Breece Hill Technologies, in conjunction with BudTool automated backup software from Peripheral Devices Corp. (PDC).

Before installing the DLT libraries, PicTel backed up the network using a 10-cartridge 8mm tape library. "We were having some hardware problems," says Silverman. "We had more exchanges of 8mm drives with the vendor than I thought was a reasonable number."

This Bud`s for you

Silverman turned to PDC for a better solution, and they recommended the Breece-BudTool combo. "I`d heard that DLT was very reliable and had good capacity and data transfer performance, and we relied on PDC to come up with a solution," says Silverman.

In addition to an 8mm library, PicTel`s backup resources now include two Breece Hill Q2.15 libraries, which each support one or two Quantum DLT4000 drives and 15 tape cartridges. Ten cartridges are in a removable magazine; the other five are fixed.

About 200 workstations are backed up over the network to dual DLT libraries, with each handling about half the load. The backup operation for workstations includes nightly incremental backups and weekly full backups.

Servers are also backed up over the network to the DLT libraries. The servers range up to 40 GB, with an average of 10 GB to 15 GB. "A full weekend backup is about 75 GB on each of our libraries," says Silverman. The BudTool backup software runs on a Sun server that is primarily dedicated to backup operations.

DLT advantages

The biggest difference Silverman has seen with the addition of DLT is superior reliability. "The backup process is pretty much the same as it is with 8mm drives," he explains, "but with the 8mm I was constantly playing catch-up. Something would go wrong with a drive, the backup would be interrupted, and we`d get behind."

Silverman also likes the fact that the drives are easy to maintain. "The read-write heads barely touch the tape, so you don`t have to clean the tape drives. That`s a real plus."

DLT cartridge capacity is another important advantage. "The fact that I don`t have to spend so much time changing tapes is definitely a benefit." Silverman typically changes only the 10-cartridge magazine and leaves the other five cartridges in the Q2.15.

"The next step will be to add a second drive to the other library," says Silverman. "We keep adding more and more disk capacity, and that has a big impact on the backup window. The second drive will back up in parallel with the first with very little loss of efficiency. That will let us do more with the same backup window."

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ATL`s WebAdmin software allows remote library administration from standard Web browsers. Management functions include library setup, monitoring, event logging, and event notification.

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