-002 Model Highlights
       The IBM 6157 Model 002 provides the same functions and features as the Model 001.  The Model 002 offers more than double the storage capacity (150Mb/cartridge) of the Model 001.  The 6157 Model 002 has a read/write speed of 150Mb in 30 minutes (approximately 5Mb 
per minute). Tapes recorded on the Model 001 are readable on the Model 002.  Tapes recorded on the Model 002 are not readable on the Model 001. 

nobel
To insert a tape, Turn the lever clockwise, pull out the drawer.  insert the tape into the drawer with the metal side down and the top of the tape to the left. Push the drawer & tape in.  Turn the lever counter clockwise.

DESCRIPTION 
       SY-TOS/IBM 6157 Tape Utilities, combined with the IBM 6157 Streaming Tape drive, provide an easy-to-use, versatile, high performance tape save/restore system.  The utilities come with two menu systems:  EZ-Function and Advance.  In addition to the menu systems, SY-TOS/IBM 6157 Tape Utilities provide the capability to enter commands directly from the DOS prompt.  SY-TOS/IBM 6157 Tape Utilities also provide a configuration utility to allow customization of the program. 
       A security system for both tape and disk access is provided. The utility supports file, partition, or disk transfers; in addition, there is the capability to restore selected files from a disk backup. 
       Multiple file sessions and disk sequences can reside on the same tape.  The ability to have several tape volumes for systems whose disk capacity is larger than the tape capacity is also 
supported.  SY-TOS/IBM 6157 Tape Utilities allow the user to restore information to another disk. 
       SY-TOS/IBM 6157 Tape Utilities provide the ability to have the system select files based on user specified criteria.  The menu systems, configuration utility, Library system, Journal option, and 
online Help system combine to make SY-TOS/IBM 6157 Tape Utilities a powerful, yet easy-to-use product. 
       SY-TOS Version 2.0 includes support for the IBM Token-Ring network and Novell(2) network operating with the IBM Token-Ring Network Adapters. 

 BSD Bob
It can be used on an RT or a PS/2 (usually a Model 80 with AIX). The standard 6157 is a 9 track low density tape drive that will run tapes from 50-1000 feet, provided you don't mind the tape wait timeouts on tapes longer than 620 feet.  The 6157-002 is the 18 track version for DC600A or DC6150 tapes.  The 002 will read the low density tapes, but not write them.  The 002 will not run longer than 620 foot tapes, in my hands.  (anyone know why?) The manuals say you should not run DC300 tapes through the thing, but I have done that on mine for years, and don't have any significant tape wear (DC300 tapes are not too common anymore so you probably won't have to worry about that).

On the RT, the thing will stream continuously on BSD, but on the PS/2, it shoeshines, unless you have a special tar with the numbers of blocks set to 2000 or such, and sufficient memory to
buffer it, or dd the tarballs out to tape.  I don't remember, offhand, what AIX does with it on the RT.

> if so, any idea how i find out what card to run  it from. i have at least one RT card that has the correct connector. a _long_ serial type.

I don't remember the card offhand, but it is the only one in the RT with the 36 pin DB connector, that I am aware of.  If you have a stock RT, that will probably be the only card that it can hook up to. I was thinking it was a half length ISA card though.  The PS/2 MCA card is a full length thing with the same connector on the back.

The drive mechanism is a Cipher.  The small locking knob on the front will break easily, but you can find a replacement from any radio shop that will usually work, or find an old Beckman DU spectrophotometer and use the light gate knob off of that for antique appeal, like I did.

Clean the head about every 20 to 30 tapes, using a cotton swab and a little isopropyl alcohol, being very careful not to get the alcohol on the drive wheel.  If the drive wheel is soft and mushy (decomposing due to bad rubber compounding), you can take a piece of ordinary gas or air hose, and usually find a size that will fit and be approximately the same diameter, and superglue it in place on the drive wheel hub. The box is a humdinger to get apart, requiring the judicious insertion
of 4 long shank flat bladed screwdrivers into the bottom locking holes (after removing the cork feet) and then gently prying the release tabs towards the centerline of the box.  Do not remove the drive mount screws until the box is open.....(:+\\......  It is a 5 handed operation. After the box is open, disassembling the drive to get at that rubber wheel is more pain, but can be done if you are careful and don't lose any parts.  Big Blue did not intend for joe enduser to open it up often.
 

>For example, which of the many cartridges will it use?
Peter says:
  The IBM 6157 (naturally a CIPHER 540S) is a QIC-150 tape drive (150MB)
   The -001 is a 60MB using standard DC-600 cardridges, may run on higher (-H and -E) but needs to reformat them after a bulk-erase. The -002 is a 120 / 150MB using DC-6120 / DC-600H and DC-600E (extended lenght).
   The 3M 600A (60/120MB) 600 feet, 12.500 ftpi / 550 hci (Oerstad) will fit in both most likely. Compatible is the BASF DC 600 HS (same data). The Mod. 002 will also like the 3M 6150 (a.k.a. 600-E / -XL extended length), the 60MB might choke on it a bit. 
   I used them on various Wangtek / Maynard 60 - 120 - 150MB with no problems.

Mark Whetzel
  The correct descriptions for the -s and -d flags of the AIX backup  command are:

-slength
      Specifies the length of the usable space on a tape medium. This is a combination of the physical length and the number of tracks on the tape. The default "length" is 2700.
    To get the value for "length", you should multiply the physical length of the tape by the number of tracks (see table below).

-ddensity
      Specifies the amount of data a system can write to a tape medium in bytes per inch. The default "density" is 700 bytes per inch.
     The density written to the tape is hardware controlled and can not be changed. The 6157-001 writes at 10,000 ftpi (flux transactions per inch) which is approximately equivalent to a density rating of 8,000 bits per inch. The 6157-002 writes at 12,500 ftpi which is equivalent to a density rating of 10,000 bits per inch.
      The -d (density) parameter is used with 0.5 inch tape drives to specify the density, such as 800, 1600, or 6250 bpi, but doesn't affect the density, that is, bits per inch, of the 6157.
      The -d parameter is used for the 6157 in the calculation of what quantity of data will be put on the tape. To increase the amount of data on the tape, the value for -d should be 1000 for 6157-001 or 1200 for 6157-002.

Reference: AIX/RT Commands Reference Volume 1, SC23-2011-1, page 91.
           AIX PS/2 Commands Reference, SC23-2025, page 35.

CALCULATION OF TAPE CAPACITY:

      The following formula yields the approximate capacity of a tape:

      # tracks * length * 11 inches * density = capacity (in bytes).

       9 * 300 * 11 * 1000 =  29,700,000 bytes or about 29 MB
      18 * 600 * 11 * 1200 = 142,560,000 bytes or about 142 MB

      The "11 inches" is the length of the recording foot, the actual amount of data stored on the tape per foot, and the interblock gaps take up approximately 1 inch per foot.

TABLE:

  For the following AIX command(s), the values for -s and -d are in the table below:

       find ./ -print : backup -iv -C2000 -f/dev/rmt0 -sXXXX -dYYYY

   Recommendations for 6157-001:

   TAPE CARTRIDGE LENGTH    TRACKS   -s    -d   CAPACITY

   3M DC 300A     300 feet     9    2700  1000    29 MB
   3M DC 300XLP   450 feet     9    4050  1000    44 MB
   3M DC 600A     600 feet     9    5400  1000    59 MB

   Recommendations for 6157-002:

   TAPE CARTRIDGE LENGTH    TRACKS   -s    -d   CAPACITY

   3M DC 600A     600 feet    15    9000  1200   118 MB
   3M DC 600XTD   600 feet    18   10800  1200   142 MB

 ================== end of included netnews article ========================
[ More of my comments now... MW ]

Nowdays the 600XTD cartridge has been replaced with the 6150 cartrige. This is the same drive that the RS6000 needs for it's original quarter inch (7207?  can't remember number soup right now) model 1 tape drive. 

> Also, is anyone using tape software other than tar or backup??? Is there any special tape software for this drive?

There was a version of SYTOS tape backup software for the RT that understood how to access the drive from AIX V2.  I have a copy gathering  dust around here someplace.

6157-001 drive   (RT 6150)
--------------
Write at 10000 ftpi =  8000 bits/in = 1000 bytes/in. Format: QIC-24
Speed 90 inches/second
Only DC300XLP recommended due to tape head wear.
By experiment, writes:
DC300XLP:  46*2000 blocks =  92000 blocks;  923*100 blocks =  92300 blocks
DC600A:    63*2000 blocks = 126000 blocks; 1275*100 blocks = 127500 blocks
DC6150:    63*2000 blocks = 126000 blocks; 1275*100 blocks = 127500 blocks
Backup flags:
DC300XLP:  -s4000  -d1000 -C2000     gives  92000 blocks. tar -s4000@1000
DC600A:    -s5400  -d1000 -C2000     gives 126000 blocks. tar -s5400@1000
DC6150:    -s5400  -d1000 -C2000     gives 126000 blocks. tar -s5400@1000

6157-002 drive   (RT 6150)
--------------
Write at 12500 ftpi = 10000 bits/in = 1250 bytes/in.
By experiment, writes:
DC300XLP: Read only
DC600A:   131*2000 blocks = 262000 blocks; 2638*100 blocks = 263800 blocks
DC6150:   157*2000 blocks = 314000 blocks; 3155*100 blocks = 315500 blocks
Backup flags:
DC600A:    -s9000  -d1250 -C2000     gives 262000 blocks. tar -s9000@1250
DC6150:    -s10750 -d1250 -C2000     gives 314000 blocks. tar -s10750@1250

> Lately there have been write errors on the drive, and the backup aborts. Other times the backup stops and just asks to reinsert the same volume (tape).  The backup continues, but gives no clue why (the tape is then <50% full).

I've come across this problem at my old job and left before it was solved.  From what I've been told by my replacement, the solution was to get an update to 2.2.1.  What would happen was, after having backed up ~50 Mb, 'backup' would come back and say "Backup MEDIUM I/O Error".  Once the updates were applied this problem went away.

  Also, backups were REAL slow for us until we found that by increasing the buffer-size which defaults to 20 blocks to 2000 blocks, it drastically decreased the time involved for backups.

  ie: The command we used:

li -Ra pathname | backup -i -v -r -f /dev/rmt0 -s10000 -d1000 -C2000

-s10000 :  18 tracks * 600 feet yields 10800 feet of tape.  I just
           chopped off 800 for safety.

-d1000  :  apparently dc600xtd (or the newer dc6150) tapes are rated
           for 1200bpi.  To be safe I used 1000.

-C2000  :  This is what actually speeds up the backup.  Default 
           without the switch is 20.  That causes a fair bit of
           tape movement.  ie: slowdown.

Just two weeks ago, I timed a backup of 65 meg on a system with 6 active users, and it took 22 minutes.  So for 250Meg you'll probably be looking at an hour and a bit.  Still pretty good.

> We use the 6157 streaming tape drives on our RTs (running Mach 2.5) to backup other machines on the same subnetwork, and it takes an  inordinate amount of time --- about 20 meg/hour.  I notice that the tape seems to have a lot of what appear to be seek failures (forward, backspace, forward, backspace, etc.)

The 6157 has to get "up to speed" before writing data. What you are seeing is the backing up that is necessary to get a running start at the next record to be written. I'm not sure that is clear, let me try
a picture.

---- write ----->
                 --- stop tape --->
(now we do the next write)
     <----- backspace tape --------
     - start --- --- write ----->
                                 --- stop tape --->
                     <----- backspace tape --------
                     - start --- --- write ----->

The -> and <- are to indicate tape movement.

The way to minimize this is to make the write blocksize as large as possible. If I remember correctly (and this was with AIX 2.2.1), I used the -C option of backup as in backup -C2000 . . . This wrote
1 meg records instead of the default. Time savings was significant.