Notes on installing Third Party DAT Drives on SGI's

The DDS1 DAT drives SGI has used in the past were Archive/Conner/Seagate Python 25601. Their DDS2's are Archive/Conner/Seagate Python 01931.

People seem to have problems with the WangDAT drives. Apparently they have some firmware problems. It might be better to go with a different drive manufacturer, unless they fix their problems. Disabling synchronous mode for the drive in both /var/sysgen/master.d/scsi and /var/sysgen/master.d/wd9[35] may help, but can cause more problems.

For some odd reason recently, Seagate seems to like keeping the fact that their DAT's can do audio a secret. Their tech. support will act like they don't know what's going on. Models numbers with an `A' at the end seem to indicate audio firmware, for example: Seagate 4326RPA. If you push hard enough and long enough, you might get a straigh answer.

Installation Help

If your system doesn't automatically recognize your DAT drive, go through the following steps so that is does:

Run `mt status' on the drive in question and you'll get an output similar to the following:
```
   Controller: SCSI
   Device: ARCHIVE: Python 28388-XXX5.63
   Status: 0x20262
   Drive type: unknown
   Media : READY, writable, at BOT
```
If the `Drive type:' is `unknow', then your system doesn't recognize the tape drive and you need to change some configuration files. The line of information you will need later, is the `Device' line.

As root, edit the file /var/sysgen/master.d/scsi and copy an entry that best matches your drive. In my case it was the DDS2 entry. Here's a sample entry:

{ DATTAPE, TPDAT, 7, 12, "ARCHIVE", "Python 01931" /*DDS2*/, 0, 0, {0},
        /* note: this drive uses modeselect page 0xf for compression control;
         * most of the other drives supporting compression use page 0x10 */
  MTCAN_BSF|MTCAN_BSR|MTCAN_APPEND|MTCAN_SETMK|MTCAN_PART|MTCAN_PREV|
    MTCAN_SYNC|MTCAN_SPEOD|MTCAN_CHKRDY|MTCAN_VAR|MTCAN_SETSZ|
    MTCAN_SILI|MTCAN_AUDIO|MTCAN_SEEK|MTCAN_CHTYPEANY|MTCAN_COMPRESS,
  /* minimum delay on i/o is 4 minutes, because when a retry is
   * performed, the drive retries a number of times, and then
   * rewinds to BOT, repositions, and tries again.  */
  40, 4*60, 4*60, 5*60, 512, 512*512, 0, (u_char *)0 },

Replace the 5th ("ARCHIVE") and 6th ("Python 01931") fields of the copied entry with your information In the case above, the 5th entry would be replaced with "ARCHIVE" and the 6th with "Python 28388". I did NOT need the "-XXX5.63" and it should NOT be added. The 6th field has a 20 character limit.
Replace the 3th and 4th fields with the lengths of the 5th and 6th fields respectively. In this case the string lenths didn't change.

If your drive has compression, you want it to work, and you are using IRIX < 6.5, also edit the file /dev/MAKEDEV.d/TPS_base. Find the section like the following:

*Drive?type:*DAT*|*Drive?type:*8mm?8200*)
    set s nrs ns "" nrns nr sv nrsv nsv v nrnsv nrv ;
    for add in 0 1 2 2 3 3 4 5 6 6 7 7 ; do
        mdev=`expr $minor + $add`;
        mknod ${prf}$1 c ${C_TPS} $mdev;
        case "$stat" {
        *Device:*Python*01931*) # DDS2 drive with compression
                mdev=`expr $mdev + 8`;
                mknod ${prf}$1c c ${C_TPS} $mdev;
                ;;
        }
        shift;
    done ;;

I changed the highligted to:

        *Device:*Python*01931*|*Device:*Python*28388*) # DDS2 drive with

This will cause the hardware compression devices to be made. The file /dev/MAKEDEV.d/TPS_base isn't used and doesn't even exist under IRIX 6.5.

I also made changes to my /dev/MAKEDEV file to create default names for the compression devices. I added the highligted lines in the `tapelinks' section.

*Drive?type:*DAT*) \
    echo \\tln -f rmt/tps$${c}d$${d}v tape; ln -f rmt/tps$${c}d$${d}v tape; \
    echo \\tln -f rmt/tps$${c}d$${d}vc tapec; ln -f rmt/tps$${c}d$${d}vc tapec; \
    echo \\tln -f rmt/tps$${c}d$${d}nrv nrtape; ln -f rmt/tps$${c}d$${d}nrv nrtape; \
    echo \\tln -f rmt/tps$${c}d$${d}nrvc nrtapec; ln -f rmt/tps$${c}d$${d}nrvc nrtapec;; \

*Drive?type:*DAT*) \
    echo \\tln -f rmt/jag$${c}d$${d}v tape; ln -f rmt/jag$${c}d$${d}v tape; \
    echo \\tln -f rmt/jag$${c}d$${d}vc tapec; ln -f rmt/jag$${c}d$${d}vc tapec; \
    echo \\tln -f rmt/jag$${c}d$${d}nrv nrtape; ln -f rmt/jag$${c}d$${d}nrv nrtape; \
    echo \\tln -f rmt/jag$${c}d$${d}nrvc nrtapec; ln -f rmt/jag$${c}d$${d}nrvc nrtapec;; \

I basically copied the previous line and added a `c' at the end of each tape name.

Finally reboot your system. This SHOULD cause a new kernel to be made with that recognizes your tape drive. If it doesn't, do a `autoconfig -f' to force a new kernel to be built and then reboot. The compression devices should also be automatically made after the reboot. You may need to delete the default `tape' names and remake the links after the system is up.

Problems

If you are having problems with your drive, here are some things to check:

SCSI ID: Make sure it is NOT 0 as this is the ID of the SCSI controller. Also make sure it is different from other devices already connected to that controller.
Cable length. Make the cable SHORT as possible. I've got an 18" (yes INCH) cable connecting our external enclosure to our machine. NO, 6 meters IS NOT the maximum cable length. 6 FEET would be pushing it. Remember there is cable INSIDE the boxes and that adds up.
Cable quality. Make sure you have high quality cables.
Termination. Make sure you have ONLY ONE terminator at the end and that it is an active terminator.
Number of external enclosures. Keep the number of external boxes to a MINIMUM. For Indys, TWO boxes it the usual maximum. One can have multiple devices in one enclosure, but keep the number of enclosures to a minimum.
Check all the dip switches/jumper settings to make sure they look reasonable. Parity MUST be enabled.
If you are connecting wide SCSI items to narrow SCSI ones, make sure the wide lines are properly terminated, other wise you could have problems. It sounds like finding such cables are difficult and that most cable makers don't do it properly.

Sample Automated Backup Setup

The following set up will backup all local file systems to a single tape if the tape is large enough. No provisions are made for changing tapes in the middle of a backup, although that shouldn't be too difficult to change. The backup script itself is set up to only do level 0 backups, but could easily be changed to do other levels.

The machine_name is used to make sure backup is only done to tape with proper machine_name label. This helps make sure backups are done to the correct tape if a single tape drive is used to backup multiple systems.

Tape labeling script: initialize_tape

Useage:

initialize_tape machine_name tape_number/name/lable

Don't use spaces or tabs in the label. If tape to be used on local machine, use "`hostname`" for machine_name.

Script executed from crontab entry: dobackups

Useage:

See crontab entry below for usage.

Script that actually does the backups: backup

Useage:

See dobackups script for usage.

Sample crontab entries:

10     2       *       *       3,4,6   /usr/local/backups/dobackups machine1 1>/usr/local/backups/machine1-error 2>&1
10     2       *       *       2,5     /usr/local/backups/dobackups machine2 1>/usr/local/backups/machine2-error 2>&1

Brent Bates' other notes on installing third party hardware on SGI's:

Working CD-ROM Drive Poll ,

Hard Disks,

Joysticks,

Magneto Opticals,

Memory, CDR's (Writeable CD-ROM's)

If you have any additions, corrects, or updates to the above information, please email me at: blbates@vigyan.com, thanks.

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Last update: May 14, 2002