D/T3590 Tape Drive Performance

Resolving The Problem

The 3590 models can achieve impressive sustained compressed data rates. However, many factors can affect sustained tape drive performance. These factors include compression ratios, data type, processor performance, applications, disk performance, bus-channel speeds, tape device data rates, data block size, network speeds, and more. Therefore, the environment of each user may vary. Let's examine the 3590 models as they relate to the iSeries 400 server environment.

Note: 3590 tape drives are not supported at V7R2 and above.

Attachment

The 3590 B-Ultra-SCSI tape drive attaches to all OS/400 releases that presently support 3590 devices: V3R2, V4R1, and later with the 6501, 6534, or 2729 IOP features with appropriate PTFs. The 3590 Model E will attach to OS/400 releases V4R1 and later on the same IOPs with appropriate PTFs (PTF list is at the bottom of this document). If attached to a Model 8xx or 2xx ISeries 400, a 2749 IOP can also be used.

Capacity

The 3590 B and E model drives use the same standard 3590 cartridge. When formatted on the B model (128 tracks), the cartridge can store up to 10GB uncompressed. When formatted on the E model (256 tracks), the cartridge can store up to 20GBs uncompressed.

o	The E model can read the B formatted cartridge.
o	The E model writes in 256 track format only and cannot write or append to a B formatted tape.
o	The E model can reformat a B format tape and then can write in the E format.
o	The B model cannot read E formatted data.
o	The B model can reformat an E format tape and then can write in the B format. The B model device must be a minimum device code level ( A_39F or B_731) to do so.

Many customers may choose to upgrade current B model drives to the E model for the additional capacity benefits provided by the E model 256 track format. The E model upgrade includes the dual Ultra-SCSI bus ports.

Performance

o	Current iSeries 400 systems using the 3590-B Ultra drive or Model E may get up to a 20% increase in performance over the 3590-B SCSI-2 (up to 60GB/hr or 17MB sustained compressed data rate) if all of the following conditions exist: -- They are using OS/400 V4 hardware. -- They are using IOP adapter FC 6534 or 6501 (not 2729). -- The current OS/400-3590 SCSI-2 can achieve maximum sustained performance today of 50GB/hr typically with large files. Note: OS/400-3590 SCSI-2 environments that do not already achieve 50GB/hr sustained data rates will not likely see any substantial performance gains when using the 3590-Model B Ultra-SCSI drive or Model E.
o	AS/400 or iSeries 400 systems using IOP 2729 will not see any performance gains when using the 3590 B-UltraSCSI or E model drive. Performance with IOP 2729 will remain at up to 47GB/hr.
o	Future OS/400 system enhancements will provide the capability for the 3590-B Ultra and Model E drive to achieve data rates in excess of 60GB/hr. Preliminary tests with forthcoming OS/400 enhancements have shown the 3590 performance at over 100GB per hour, up to 30MB.

Performance Note: Sustained data rate performance figures are estimates and are subject to the user environment including processor performance, data compression ratio, bus speeds, file types, application, and so on. User results may vary. Product plans are estimates and are subject to change or withdrawal without notice.

Summary

Today, an UltraSCSI B or E model drive should get similar performance on the current iSeries 400 systems. The user could get up to 17MB/second sustained data rate (60GB/hour) on the 3590 Ultra-B or E models assuming that the iSeries 400 system is at V4 hardware and the IOP adapter is a 6501 or 6534 and assuming large files with optimum blocking. With a user mix of data the data rate is typically about 9MB/s. The bottleneck is not the 3590. As the iSeries 400 group delivers future iSeries 400 system enhancements, the performance of the 3590 could far exceed 17MB/second. Users with additional capacity needs may choose the 3590 Model E today for the double cartridge capacity benefit and performance potential.

UPDATE: When using a 2749 IOP with R450 or above, transfer rates of 27MB/s can be achieved.

PTF Listing for 3590 B-Ultra and E

The following are the minimum required (many if not all of these have been superseded) for the 3590 B-Ultra and the Model E:

	6501	6534/2729
V3R2	None	N/A
V3R7	None	N/A
V4R1	None	MF20571 and MF20545
V4R2	None	MF20552 and MF20569
V4R3	None	MF20514 and MF20515

The following are also required for the 3590 Model E:

	6501	6534/2729	XPF
V4R1	MF22182	MF22176	SF56460
V4R1.4	MF22181	MF22175	SF56461
V4R2	MF22180	MF22174	SF56465
V4R3	MF22179	MF22173	SF56462
V4R4	MF22178	MF22172	SF56463

Note: 3590 tape drives are not supported at V7R2 and above.