Feature

Tape libraries automate backup

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The new generation of tape drives or "super drives" such as LTO, Super DLT, AIT3 and Super AIT will have a dramatic affect on library automation (see "How new generation tapes change libraries" below). The increased cartridge capacity and transfer rate performance of super drives will increase the density and reduce the size of libraries, which will need fewer slots and less media.. That will help maintain tape's 60-fold cost advantage over disk, while providing faster data access to enhance applications


How new generation tapes change libraries

The latest generation of tapes will have a dramatic effect on library automation as they add capacity and capabilities to libraries.
TECHNOLOGY VENDOR EXAMPLE TAPE CAPACITY (NATIVE UNCOMPRESSED)

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SUSTAINED TRANSFER RATE (NATIVE) INTERFACES SUPPORTED FORM FACTOR MEDIA AUXILIARY MEMORY IN CASSETTE
8mm Helical Sony
AIT-3
100GB 12MB/s IDE
SCSI, Fibre
3.5 AME 64k MIC
LTO HP, IBM
Seagate
Ultrium
200GB 20-40MB/s SCSI,
Fibre
3.5
5.25
MP 32k CM
SDLT 320 Linear Quantum
Super DLT
160GB 16MB/s Ultra2,160
SCSI
5.25 AMP No
S-AIT Helical Sony 500GB 30MB/s Ultra SCSI
160, Fibre
5.25 AME R-MIC
VST (DLT1) Linear Benchmark
VST80
80GB 6MB/s SCSI 3.25 MP No
Source: Open Systems I/O Evaluator Group, Chapter 4, 2002.

On the downside, super drives are not designed for the high duty cycles of the enterprise market. Enterprise class drives like StorageTek's 9840/9940 and IBM's 3480/90 should be used where duty cycles exceed 50%.

Tape libraries are great in SANs
Currently, the killer application for SANs is backup/recovery. Today, most SANs are connected by FC. The FC option on a tape drive costs more than SCSI. FC tape drives are needed in high-end library applications. Until the FC option cost comes down, it's less expensive to use routers and bridges to support multiple SCSI drives in a library. However, it is better to use native support than convert. Also, care must be taken to address the FC topology. For example, special ports or switches are needed that support arbitrated loop.

When using storage resource management software, make sure it's compatible with your tape library and HBAs, switches, and operating systems.Keep in mind that testing should be down to the firmware level. Don't mix and match - use tested, validated configurations. Once you arrive at a stable configuration, your tape library can aid in:

Serverless backup. Most backup software ISVs allow the tape drive to be the initiator in the SAN. Backup is much faster through a host and doesn't degrade the network.

Disaster recovery. SANs can be bridged or linked over large distances by iFCP, FCIP and soon, iSCSI. Even if you have redundant RAID, snapshots to a tape library are required as there are too many single points of failure such as software corruption, viruses and sabotage. Using the right backup software, a SAN can also split or duplex the write to a remote location.

SAN management and virtualization. Used to reduce the complexity and proprietary nature of SAN solutions. Tape, disk and memory strengths are blended and used proportionately to reduce cost. Tape is represented as an image on disk and then tapes are completely filled using volume stacking. StorageTek and IBM are the leaders in this market. SAN virtualization will become important.

Tape striping or redundant array of inexpensive taped (RAIT). This approach works for high bandwidth applications such as telemetry and seismic data. Currently, RAIT applications don't share data well in a SAN, due to EOT and other specific differences. Specialized software will be an important part of your tape library selection for this application.


Popular libraries and tape drive support
Cartridge
slots
ADIC ATL Exabyte HP IBM Overland Data Inc. Storage Technology Inc. Qualstar
20 S100 DLT LTO SDLT M1500/SX DLT LTO SDLT 221L LTO 230D DLT 2/20 DLT LTO 7337 DLT 3570C/XL Non DLT LXM, NEO DLT SDLT LP2/3 AIT L20 DLT DLT1 LTO SDLT 4420 AIT 6220 DLT DLT1 SDLT 8222 LTO
40 S100 DLT LTO SDLT AIT M1500x2/sx DLT LTO SDLT P1000 DLT SDLT 430M Mammoth 4/40 DLT LTO 3583 LTO 3575L06 3590 NEOx2 DLT SDLT L40 DLT DLT1 LTO SDLT 4440 AIT 64xx DLT 6430/60 DLT1 SDLT 84xx LTO
80 S100 DLT LTO SDLT AIT M1500x3/x4 DLT LTO SDLT P1000,7700 DLT SDLT A2000 AIT X80 Mammoth 6/60 DLT LTO 3583 LTO NEOx3 DLT SDLT L80 DLT DLT1 LTO SDLT 4480 AIT 64xx DLT 6460 DLT1 SDLT 68120 SDLT 84xx LTO
180 S1000 DLT LTO SDLT AIT M1500x9 DLT LTO P2000 DLT LTO SDLT P4000 DLT LTO SDLT X200 Mammoth 6/140 DLT LTO 10/180 9840 DLT LTO 3584-227 LTO 3494 3590 3575L18 3590 NEOx7 L180-140 9840 9940 DLT LTO SDLT 412180 AIT 68120 DLT SDLT 88132 LTO
700 S1000-390 /698 LTO S1000-390 SDLT S1000-418/ 668 DLT S1000 AIT S10K AIT DLT LTO SDLT A6000 AIT P7000 DLT LTO SDLT P4000 DLT LTO SDLT   20/700 9840 DLT LTO 3585-227/ 667 DLT LTO 3494 3590   L700-396/ 678 9840 9940 DLT LTO SDLT 412600 AIT 68240 DLT SDLT 88264 LTO
Source: Evaluator Group

This was first published in June 2002

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