Removable Storage Media Devices
374 AS/400e System Handbook
IBM 3590 High Performance Tape Subsystem Models E1A and E11
The IBM Magstar 3590 High Performance Subsystem Model E11 tape drive is a
rack-mountable model using high performance ½-inch tape cartridges. The 3590 E Models
can read or write twice as much data as the B1X Models on the 3590 High Performance
Cartridge Tape. With the E1X Models, the cartridge can contain up to 20 GB of
native/uncompressed data per cartridge (60 GB with a 3:1 compression ratio).
The 3590 E Models use an advanced serpentine recording technique, which makes sixteen
passes along the tape to provide greater capacity and performance. The head element is
composed of two groups of 16-track read/write heads. The 3590 writes 16 data tracks at a
time to the end of the tape. Then, it electronically switches heads to write 16 different
interleaved tracks and records back on the tape to the beginning. The head is indexed
(physically moved) slightly to record the next set of tracks. A total of 256 tracks are recorded
on the 3590 cartridge. Fully written tapes are positioned back at the load point, virtually
eliminating the rewind operation as with 3490E tape drives. The “locate” function has been
enhanced to position the drive on the proper track and location without having to sequentially
search the entire recorded tape. The 3590 cartridge tape has servo tracks written on it.
These tracks enable the 3590 drive to accurately position the read and write head, with
respect to the media while the tape is in motion.
The Model E11 includes a ten-cartridge Automatic Cartridge Facility (ACF) with a cartridge
magazine. This magazine has a random mode operation feature that allows random access
to any cartridge in the ACF. Status indicators on each cell of the ACF alert the operator to
conditions that may need to be addressed. The ten-cartridge ACF, coupled with increased
capacity of the 3590 cartridge, reduces the frequency for operator interaction with the tape
subsystem. The increased capacity of the 3590 cartridges allows the ACF to typically contain
from 200 GB native to 600 GB with a 3:1 compression ratio of data. Other standard features
include a 16 MB dynamic data buffer, an improved data compression, auto-blocking of small
records, and one-pass-read-after write. Drive reliability includes the use of an enhanced error
correction code and the use of servo tracks for read and write.
The IBM 3590 Exx models have a 14 MBps device data rate, which is 50% faster than IBM
3590 Model B11/B1A Tape Drives. With compression, the 3590 drive on the AS/400 system
may achieve a sustained data rate of up to 17 MBps with compression or 60 GB per hour for
large files. The actual throughput achieved in a system environment is a function of many
components, such as system processor, disk data rate, data block size, data compressibility,
I/O attachments, and the system or application software used. Other operating
characteristics are:
• Tape speed: 3.14 meters per second (124 inches per second)
• Search/Rewind speed: 5 meters per second (198 inches per second)
• Full cartridge rewind time: 2 seconds
• Maximum rewind time per cartridge: 60 seconds
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