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5. Tape

(No compression added in calculations unless specified otherwise)

5.1. Cartridge vs Cassette

Cartridge has only one reel (i.e. 3480, DLT). Cassettes have two reels (i.e., 8mm, 4mm, 19mm, VHS) and may not need to be rewound to dismount.

5.2. Longitudinal

have heads that write bit streams that are parallel to the edge of the tape.

5.3. Serpentine

are longitudinal that write the full length of the tape, then turn around and write the length of the tape in the opposite direction with the heads in a slightly different position. This process may repeat many times.

5.4. Helical Scan

are like your VCR with a rotating head mounted at an angle writing "swipes" at an angle not parallel to the edge of the tape. The tape is moved only slightly between swipes. Two or so longitudinal tracks may also be used for fast positioning purposes.

5.5. Tape Media Lifetimes (Longevity) {Brief}

See and for some info on this topic. Other contributions gladly accepted, this topic comes up frequently in the newsgroup. (rdv, 1996/3/20)

5.6. 9-track {brief}

The old 2400 foot round reel of tape written at 800, 1600, or 6250 BPI.

5.7. 3480/3490/3490E {brief}

        Square cartridge:
                IBM 3480 - 18 track - 200 MB/cartridge, 1984
                IBM 3490 - Smaller packaging, IDRC standard, 1989
                        reports that it is a 3480 in ID string
                IBM 3490E - 36 track, double length - 800 MB/cartridge 
		native, 1992
        	IDRC data compression is also available.

These drives have traditionally come from the mainframe vendors -- IBM, Fujitsu, Storage Tek, etc. They were originally very large objects, with vacuum columns and mainframe interfaces, the size of large filing cabinets.

However, recently they have become available in smaller packages, 19" rack mount or table top, and with interfaces such as SCSI.

Here's one from last year that I recently dug out of some old mail:

IBM has just made generally available the following:
  3490E Model E SCSI tape drive
  fast/wide differential
  IDRC compression
  3 MB/sec at the tape head, 6.5 MB/sec with compression
  approx 800 MB tape capacity with out compression, 2.4 GB with a 3:1 comp
  7 tape CSL(cartridge stack loader)
  Desk top and rack mount
  List $27,000, 94/4/11

There's also a standalone drive with a small autoloader from a company called Overland Data. Their L490e is a win because it reads and writes both 18 and 36 track tapes. At $20K it's reasonably priced. For the www-enabled, see (, 94/12/21)

5.7.1. New IBM Tape (NTP) 3590

Same form factor as 3480, serpentine. 9 MB/sec., 10GB/cart. Bare drive should retail ~$35K, 1Q95. Two SCSI interfaces? Robotics also planned. (, 09/30/94)

NTP has been released (95/4/10) as the 3590 tape subsystem with the Magstar tape drive. The press release didn't mention price, availability, or interfaces (though it did say attachable to Suns, RS-6k, etc.).

list price for the 3590 drive is approximately $43.5K; list for media is approximately $50; list for 3590 drive + 10 cartridge stacker is approx $48K (95/9/18,

IBM Storage has an excellent WWW page at

5.8. Magstar Coyote (IBM 3570) {Brief, New}

There is a second type of tape drive from IBM based on the Magstar technology. Known as Coyote or 3570, it's 2.2 MB/sec., 5GB in a two-reel cassette. Unlike 3590, the tape never leaves the cassette. The width of the tape is much less than 1/2", maybe 1/4"? The cassette is about the size of an 8mm, give or take. There's an associated desktop modular autochanger. (rdv, 97/6/5)

5.9. QIC {brief}

Quarter Inch Cartridge. Primarily low-end (ie, PC) available from multiple vendors but 3M is pushing it into midrange market with estimates of 100 Gigabytes per cartridge by 1999. Two-reel cassette.

In Dec '94, 3M, Sony, HP and others announced a new format, 2.3 times the capacity, available mid-1995. The cartridge and drive mechanics apparently change. It will be .315 inch tape instead of .25, with 750 feet of media in a cartridge. (rdv, 94/12/16)

5.9.1. Travan

Travan is a 3M trademarked name for a new family of data minicartridge tape media. Travan provides additional capacity via longer length(750' / 229 meters) and greater width(.315" / 8mm) tape then previous generations of data minicartridge. Drives that can accommodate Travan cartridges must have a mechanism that can handle wider tape (.315" / 8mm vs. earlier data minicartridge that are .25"/6.2mm) and be able to accept the slightly larger Travan cartridge. All major drive manufactures have modified existing drives or designed new mechanisms to accommodate the Travan cartridge. Today's Travan capable minicartridge tape drive maintains the industry standard QIC formats. These drives can write and read smaller capacity data minicartridge tapes of the same QIC format family(See below).

Travan TR1 capable drive functionality
Cartridge 	Format		Capability	Native Capacity
DC2120		QIC-80		W/R		120MB
DC2120XL	QIC-80		W/R		170MB
QW5122F		QIC-80		W/R		208MB
TR1(Travan)	QIC-80		W/R		400MB

Travan TR3 capable drive functionality
Cartridge 	Format		Capability	Native Capacity
DC3010XL	QIC3010	              W/R		346MB
QW3010XLF	QIC3010	              W/R		425MB
DC3020XL	QIC3020	              W/R		692MB
QW3020XLF	QIC3020	              W/R		850MB
TR3(Travan)	QIC3020	              W/R		1600MB


1. TR3 capable drives can read only all combinations of QIC-80 formatted
2. 3M has developed a TR2  800MB QIC3010 format tape but has not gone to
market with it at this time
3. There will be TR4 and greater media products in the future. These
products will offer greater capacity and performance.

(thanks to, aug 16 1995) TapeStor {brief,new}

The TapeStor 800 and 3200 from Seagate are Travan TR1 and TR3 drives, respectively, targetted at the home PC market. (rdv, 96/11/4)

5.10. 4mm {brief}

Multiple vendors. Initially for home audio market. Original product held 1.3 GB on one 60 meter tape at about 180 KB/second. Search speeds run about 200 times nominal speed. DDS (Digital Data Storage) format has overtaken the DATA/DAT format. Two-reel cassette. gives HP DDS drive information gives specs for the DDS2 C1533A

5.11. 8mm {brief}

Sony developed transport designed initially for home video market. Exabyte has U.S. rights with Kubota qualifying as a second source when needed.

EXB 8200 model holds 2.3 Gigabytes per tape at 220 KB/sec

EXB 8500 model holds 5 Gigabytes per tape at 500 KB/sec

Search speeds of the 8200 is dismal, but is significantly improved in later models. Compression and half-height (standard is full-height 5.25-inch) features are also available.

See for more info.

5.11.1. Mammoth (EXB-8900) {Brief}

Mammoth is the new Exabyte drive. It holds 20 GB uncompressed per cartridge, with a transfer rate of 3 MB/s. Exabyte has been touting this drive since at least April '93; it is now shipping. SCSI-2 fast or fast & wide interface. Read (not write) compatible with all older Exabyte drives. (rdv,96/11/1)

5.11.2. Sony SDV-300 {New}

An article in Computer Tech Review says that Sony has announced a 25GB native 3MB/sec 3.5" 8mm drive based on the same media technology they developed for Exabyte's mammoth.

At this point (June 10, 1996), opinions in the newsgroup differ as to whether or not the _media_ is compatible with Exabyte's Mammoth, though everybody agrees that SDV-300 will not be read or write compatible with Mammoth or earlier Exabytes.

Sony's new drive does look impressive. The information that I have says that production shipments begin this summer (late July for initial shipments) for units without the data compression feature. That would be 25GB native capacity @ 3MB/sec. Drives with compression will ship in 4Q96, for a guess, probably October-ish.

The interesting feature is the NIC cartridge that has positioning information due out by mid-97 that will eliminate the need to rewind before unloading the tape and will allow the tape to seek in either direction on loading. This is a flash chip built into the cartridge itself.

The SDX-300C is apparently one model in this line, already shipping in some autochangers. No flash index chip yet. (rdv,96/11/4)

(Jeff Johnson (, Bob Covey ( and others, 1996/6/10)

5.12. DLT {full}

See for info on current issues concerning DLT.

Also see the DLT FAQ, maintained by Larry Kaplan, For Suns, there is info at

Digital Linear Tape (DLT)
TZ87 (DLT2000) - 10 GB native per cartridge
See also robotics (DLT2700 is 7 tape library)
Ref: Digital's Customer Update, March 14, 1994
Serpentine recording.

Developed from DEC's TK50 & TK70 technology. The unit that developed this was sold to Quantum.

DLT is the new tape technology getting the most air time around here. There is also a DLT-specific FAQ maintained by Larry Kaplan from Quantum.

See for specifications, for some FAQ answers. I also have an old copy of Larry Kaplan's different FAQ available at

From the newsgroup:

Tape uses a special hook for load/unload mechanism.

DEC is the initial vendor, but other vendors are re-selling them (sort of like TTI's reselling of the Exabyte 8mm tape drive).

Transfer rate of 2.5 MB/sec, but that assumes 2:1 compression, so it is 1.25 MB/Sec native. Likewise the 20 GB cartridge is 10 GB native.

DLT4000 ($2K upgrade from DLT2000) soon (9/94?) Double the capacity. Some agreement with Cypher. Still not shipping in quantity, 1/95.

Can be used on NON-DEC systems (standard SCSI interface).

One report of a batch of tapes that were "too wide".

> (Michele Michelotto) wrote: >You're comparing the top QIC format with the rather new DLT tecnology. What is so special about DLT? I'll try to answer:

>1. Serpentine format means that there are several parallel tracks. the head goes down the first track and comes back down the second one etc. If I need to access a file at the end of the "logical tape" and the drive knows that it is at the beginning of the 52th track it goes directly to the 52th track and start seeking on it. So the worst case access time is close to the rewind time (about 100 sec) the average access time is about (60 sec).

>2. the unit I tested was a 6 GB/cartridge (no compression) 700 kB/sec. the cartridge had 112 tracks but since the drives use two heads, it could access track N and track N+54 together. So it looked like a 54 track cartridge. Now it's very easy to put 4 (or 8) heads in the drive and double (or multiply by 4) the transfer speed while maintaing the backward compatibility (with 8 head you use only head #1 and #5 to emulate a 2 heads unit).

>3. DEC is selling to the OEM a DLT4000 unit with 20GB uncompressed (40GB with compression). [may be available 9/94]. [Thinner, longer tape plus somewhat higher density and slightly more efficient packing/blocking]

DLT cost $5K US for 20GB drive, $10K for a 140GB stacker, $150K for a 3.2 TB robot.

Autochangers are made by DEC, Odetics (available through EMASS) and Metrum (now MountainGate).

Piping tar into dd, with a bs=64k can increase your speed.

The drives have a tape mark directory that is used for a SPACE command, but if you just SPACE 1 FILEMARK multiple times, efficiency is poor (and is the fault of the software implementation as it should "SPACE n FILEMARKS").

Submitted (approved?) ANSI standard, but that does not mean anyone other that DEC is doing anything more than OEM'ing it.

5.12.1. DLT7000 {Brief}

35 GB on a cartridge (uncompressed), 5 MB/sec. transfer rate. Drives available in limited quantities now, general availability was targetted for June/July '96, but still apparently months away? (Alex Brill,, 1996/2/23, updated rdv, 96/7/8)

5.12.2. DLT4000

Streaming tape drive
Quoted 40 GB includes 2:1 compression
Quoted 3.0 MB/sec includes 2:1 compression
Extended 5.25-inch form factor
SCSI-2 interface, either single-ended or differential, 
optional fast SCSI.
Compression is DLZ (Digital Lempel-Ziv)
"...a head life of 10,000 hours (compared to 2,000 hours for 
other tape products), a recommended average of 10,000 read/writes per 
cartridge, and an MTBF of 80,000 hours."
Search speed averages 68 seconds
Repositioning time 1.3 seconds
Hard error rate: 1 x 10**17 bits read
Undetected error rate: 1 x 10**30 bits read
Serial serpentine (128 tracks), variable block
bits/inch: 82,000
Tracks/inch: 256
Recording media: CompacTape (tm) IV
0.5 in x 1,700 ft x .3mi thick
Cartridge: 4.1 x 4.1 x 1 inch
shelf life: 10 years
Height: 3.235 in, width: 5.7 in, length: 9 in
Reliability: 80,000 MTBF
Media reliability: 500,000 passes in start/stop mode (or an 
average of 10,000 uses/cartridge)

5.12.3. DLT2700 (from DEC)

random access, seven tape, 1 drive library
rack mountable 8-inch form factor
includes operator control pannel and LED indicators
400,000 mean mechanical cycles before failure
uses a 7 cartridge magazine.
Magazine "precheck": 75 seconds per magazine
Cartridge load (max): 28 seconds
Cartridge unload (max): 30 seconds
SCSI command set for robotic commands
Subsystem reliability: 30,000 power-on hours
Height: 10.4 in, width: 8.7 in, length: 27 in
weight: 65 lbs
same as the TZ877?

5.12.4. DLT2000 (from DEC (now Quantum))

CompacTape (tm) III
Capacity: 20 GB/cartridge
        (assumes 2:1 compression)
1.25 MB/sec. (Rodney D. Van Meter), (Peter Van Epp),,, rrohbeck@ufhis.enet

5.13. MountainGate (was Metrum) VHS {brief}

	800-556-0222 or 702-851-9393 Phone
	702-851-5533 Fax
	in Europe: Mountaingate Data Systems Linda Radley in the UK
	+44-1256-464-767 (tel) +44-1256-597-48 (fax)
        Drive: RSP-2150, 2MB/sec sustained, 4MB/Sec burst
        ST-120 cartridge holds 14.5 GB
        ST-160 cartridge holds 18 GB
        See also robotics

Integrated with lots of SW packages, and drive prices have come way down. I think you can now get them for less than $15K. Integrates smoothly with robotics.

See for one performance evaluation. Lots of good info there, but keep in mind that the testing was conducted in 1992.

5.14. VCR VHS

This appeared recently in the newsgroup, but I don't know anything about it. This is the widget that takes data in one end and spits out a video signal that you can pipe into your home VCR to use your it for data storage. It's only $350, but, for those of us in the U.S. and Japan, it doesn't work for NTSC VCRs.

Subject: VTS Tech Specifications for Users
Date: Mon Nov 28 09:24:29 PST 1994

Having received a lot of questions from different users of VTS 1020,
I'd like to answer them giving short specifications of this unit.
1. CAPACITY: 4 GB Compressed / 2 GB Uncompressed on one E-180 cassette.
             The amount of data grows according to the tape length.
2. SPEED:    100 KB/sec for PC/AT 286-16 Mhz
             200 KB/sec for PC/AT 386-33 Mhz etc.
3. SOFTWARE: The current version is for DOS. Windows support-DOS Window.
             Read/Write verification is provided.
4. VIDEO:    PAL/SECAM System, VHS Tape

Also from the newsgroup a while back:

We, AT Systems Inc., are distributors of VCR cassete backup kits (including PC board and software package with 1 year warranty and 2 weeks money back policy), please send all inquiries to my e-mail address (Michael V. Kuzmin,, 4/95)

And more recently:

Check out a company call Cybernetics in Yorktown, Virginia. They put Sony VCR drives in their own enclosures for backup devices. Contact Thomas Dougherty at (804) 833-9000. (Mike Rothenberg,, 1996/4/1)

5.15. 19MM (D1 and D2) {Brief}

19mm is 3/4 inch helical scan tape. Two varieties exist, D1 and D2. Both originated from broadcast and/or data recorder applications, where the data/signal was analog in nature. They have been modified for digital use, with error correcting capabilities added.

Data rates are in the 8-45 MByte/sec range, with storage capacities in the 25-175 GB range in physically different size cartridges with different length tapes, but all fitting into the same tape drive unit.

5.16. ID-1

SHMO: I'd like to hear more of people's experiences using these things.

Note: I would recommend you talk to people who've used these things before buying one!

5.16.1. DATATAPE

DATATAPE (Pasadena, CA, formerly a division of Kodak), has an ID1 system available, with a HiPPI interface. You can find more info and even give them design feedback at The DCTR-LP400 goes up to 50 MB/sec., the fastest single general-purpose tape drive I know of. Reachable by phone at (818)796-9381 (rdv, 96/8/7)

5.16.2. Sony

Sony makes several models of a D-1-based data drive; the format is generally referred to as ID-1. It comes in different models, with equivalent price tags, that run from 8 to 32 MB/sec. The original machine had a VME interface that was extremely low-level ("any lower and you'd have to turn the spindles by hand," someone said); now there is a HiPPI interface available from a company called TriPlex. I understand the HiPPI interface also adds another layer of ECC to improve the otherwise abyssmal error rate (10^-10 becomes ???). Sony is also supposed to be doing their own SCSI and HiPPI interfaces. I don't know the status nor if they are compatible with tapes from the TriPlex unit (I suspect not).

SONY has announced 3 interfaces so far. ;-)

DFC-1500 - SCSI interface

DFC-1700 - FW-SCSI-2 interface

DFC-1800 - 8 bit ECL interface that acts as a "scrollable" buffer.

All of the interfaces are fully buffered. They list for 40K-88K.

I have used the DFC-1700 for some time. From the standpoint of SCSI functionality it is quite good. It obeys the MT commands and if you wish you can either write to it in "raw" mode or DTF, which is SONY's version of the DD-1 spec. On an HP I get 14+MB/Sec on the DTF side and near 16MB in RAW mode.

TriPlex makes an interface that does SCSI,FW-SWCI-2 and HIPPI. The price varies. List for the HIPPI version is in the $130K range. The controller is fully buffered.

Myriad Logic also builds boards (VME) and a controller. The controller was demonstrated in Europe this year. It is a HIPPI attached controller built out of their existing products. No good feel for the price, but I would GUESS that it will be less than 90K. It is also fully buffered with 384MB of VSB memory.

These are very expensive -- $100K+, but for people with the need, they've got the speed.

(, (John Stephens), (Rod Van Meter), (stephen w. poole) (8/95))

Sony's sales literature now (1996/3/22) says they plan to introduce a 64 MB/sec. drive "in the near future". (rdv)

5.17. D-2

Ampex supports D2. Data rates are in the 15 MByte/sec range.

The Ampex tape transport and head system were originally sold through E-Systems (EMASS), who built the storage controller and sold it as the ER-90 and coupled it with Odetics robots. Ampex now makes their own interface for the unit, sold as the DST. They also make their own very fast robotics.

The ER-90 is popular with the oil crowd. I don't know if the tapes are interchangeable with the DST.

(rdv, 12/94)

DD-2 (19mm Data D-2 Format)

Ampex DST General:

3 cartridge (cassette) sizes - 25, 75, 165 gigabytes (uncompressed). 15 megabyte/sec. sustained (20 megabyte/sec. burst) transfer rate (per drive). Up to 800 megabyte/sec. search speed (per drive). Smart DD-2 format includes partitioning and system zones to maximize storage efficiency and speed data access. 3 layers of Reed-Solomon error correction, with read-after-write verification and automatic rewrite yield error rate of 1 in 10E15 bits read. Drive(s) dual ported SCSI-2 (16 bit fast, differential).

DST 310 Tape Drive:

All 3 cartridge (cassette) sizes supported - 25, 75, 165 gigabytes (uncompressed). Rack mount or table top configurations. Single unit price: $120K.

Ampex recently (dec. '95 or thereabouts) announced a new tape drive model that's substantially cheaper, ~US$80K. Still 15 MB/sec., but I think it only supports S cassettes.

Ampex Corporation
401 Broadway, M.S. 3-46
Redwood City, CA 94063-3199
Inquiry:  415-367-2982
Facsimile:  415-367-3850

(see also Ampex under autochangers -- they make their own for this tape drive)

(, 94/12/23)

5.18. StorageTek Helical {Brief}

Storage Tek has been working on a project called Redwood for a number of years. The cartridge will be 3480 form-factor, to protect users' investment in Storage Tek robotics. ( (Rod Van Meter)) Cartridges come in three lengths, with capacities of 10, 25 and 50 GB. That would put one of their 6,000-cartridge silos up to 300 TB.

The ESCON interface is in betatest; SCSI fast & wide due out soon. (, 94/12/19)

Reportedly available now (95/5/15) with the SCSI interface; ESCON has been delayed until end of the year.

Sustained transfer rate of 11.25 MB/s. Supports compression. List price ~$100K.

Compatible with most of the STK robots. See and also autochangers in part 2 of this FAQ.

5.19. Optical

A company called Creo, from Canada I believe, makes a large tape drive that uses ?1"? tape and gets a terabyte of data on a $10,000, 880 meter reel. The time to read the media (media granularity) is huge; at 3 MB/sec. it takes almost four days to read a tape!

EMASS have aquired the rights to manufacture the optical tape drive from CREO. The drive ($350k) provides 1TB on line with data transfer at 3MBytes/sec and an average seek time of just 30 seconds. Optical tape media is supplied on 12.5" reels (capacity 1 TByte) by ICI Imagedata in the UK. Expected archival life 30yrs. Typical price of a reel is $8,500. (updated 1995/9/18, has some info.

5.20. D-6 {brief}

From Toshiba & BTS, originally designed as a full-speed (~150MB/sec.) digital HDTV VTR. A model with a HiPPI interface is supposed to be available end of 94. The video version is priced at US$300K+. I believe the tape transport and cartridge are the same as for D-2, though the tape material is different.

(4/94, rdv)

5.21. D-3 {brief}

From Martin Marrieta, mentioned here on the net recently. Very fast (10.8 MB/sec.), ~$125K. General availability scheduled for 11/14/94 (9/20/94, I believe the cartridge is the same as Betacam, so look for the broadcast autochanger companies here (rdv).

5.22. Sony DTF {Brief}

Sony DTF is also a helical scan device, utilizing 1/2" digital data cartridges, same form factor as Digital Betacam. Capacitities of 12 (small cartridge) and 42 Gigabytes (large cartridge) UNCOMPRESSED at a sustained transfer rate of 12.2 MB per second again UNCOMPRESSED with and error rate of 10 to the -17. MTBF 200,000 HRS.

INLINE sells this as the INLINE RES-400. Cost $55,000 per transport with 16-bit SCSI differential interface.

800.465.4637 or 703.478.0800 main, 703.478.0966 fax

(John Tibbitts,, Oct. '95)

Also available from Cybernetics, EMASS, Transitional Technology here in the U.S. and several others in Europe and Asia (contact rdv if you're interested in contacts). One of these makes an SBCON interface for the drive. No Fibre Channel or HiPPI yet that I know of. Not available directly from Sony.

(updated rdv, 1/96)

5.22.1. GY-2120 {New}

Sony introduced the GY-2120 DTF tape drive in March of 1997. This is a re-engineered version of the first DTF drive, GY-10D. It is now a one piece, smaller and lighter version with added features. Best of all, the new suggested list price is $31,000.00.

     12 MB/sec sustained data rate
     up to 20 MB/sec w/compression
     42 GB Native Capacity
     108 GB w/compression
     ALDC High Performance Compression, Average ratio 2.59:1
     Automatic Head Alignment
     Automatic Head Cleaning system
     Automatic Tape Cleaning system
     300 MB/s Search Rate
     Fast Unload/load of < 25s
     Head Life > 5,000 hrs
     MTBF: > 200,000 hrs
     Read/Write Passes: > 20,000
     Tape Archive Life: up to 30 years
     Distribution has changed as well, we now sell to VAR's and through 
     Sony's Broadcast Division in addition to OEM's:
     OEM's:     Cybernetics
                Precision Echo
     VAR's:     Ovation Data Services
                Performance Group
                RFX, Inc.

( (Wes Kuch), 1997/6/24)

5.23. DATATAPE DTR-48 {Brief}

In addition to their ID-1 tape drive, DATATAPE makes a 1/2" tape drive called the DTR-48, 6 MB/sec., 35 GB on a cartridge. I believe the cartridges are the same physical form factor as Betacam. (rdv, 96/8/1)

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Copyright 1996 Rod Van Meter