IBM produces its own proprietary, enterprise or mainframe line of tape drives, the 359X family. These are the top end of IBM's tape offering, underpinned by its mid-market LTO models, known in IBM-parlance as the 3580. We described LTO's characteristics here.

IBM also provides what it describes as complementary tape products:- - 7205 - a DLT or SDLT format drive. - 7206 - a 4mm DDS format drive, also in VXA-2 format. - 7207 - an SLR and QIC tape format drive. - 7208 - a Mammoth format drive.

You may encounter references to 3480 and 3490 drives. These are not current.

We cover IBM's older generation proprietary format, the 3590 in its B, E and H iterations first, and then look at the newer 3592 and its roadmap.

This is a half inch linear tape format with tracks running up and down the tape. IBM provides three basic versions of this with progressively greater capacity.

3590 B 3590 E 3590 H
Raw Capacity 10GB 20GB 30GB
Compressed Capacity 30GB 60GB 90GB
Raw Transfer Rate 9MB/sec 14MB/sec 14MB/sec
Compressed Transfer Rate 27MB/sec 42MB/sec 42MB/sec

IBM quotes high compression ratios, 3:1 in fact, higher than other vendors. The 3590 H can, it's said, transfer data at up to 70MB/sec with a Fibre Channel link. It's up to 34MB/sec using UltraSCSI. The drives can use mainframe ESCON and FICON channel interfaces as well as SCSI and Fibre Channel.

The 3590 B has 16 read/write heads and 128 tracks. The 3590 E has 16 heads and 256 tracks. The 3590 H has 16 heads again and 384 tracks. The use of BX, EX and HX cartridges doubles the capacity in the 3590 B, E and H drives respectively.

Host servers can be the various IBM servers plus Sun and HP Unix/True64 Unix systems.

This is the future. Once again it is a half inch, linear format. The current 3592 drive has 8 read/write heads and 512 tracks. There are two future generations which IBM has indicated will lead to a cartridge with a terabyte capacity. We have extrapolated numbers from the 3592 to indicate the characteristics of them. These are our estimated numbers.

3592 Gen 2 Gen 3
Raw Capacity 300GB 600GB 1TB
Compressed Capacity 900GB 1.8TB 3TB
Raw Transfer Rate 40MB/sec 80MB/sec 160MB/sec
Compressed Transfer Rate 120MB/sec 240MB/sec 480MB/sec

IBM has demonstrated a terabyte cartridge in its R&D facility. We might speculate that the second generation 3592 tape will arrive in 2005/ 6 and the third generation will appear in 2007/ 8.

The 3592 connects to hosts by FICON or ESCON channels or via Fibre Channel. Hosts can be mainframe, Unix and Windows servers.