Apple DAT Drive
| Apple DAT Drive | |
|---|---|
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|
| Loading a tape into the DAT drive of a Workgroup Server 8150, from Apple's administrator's guide | |
| Manufacturer | Hewlett-Packard, for Apple Computer, Inc. |
| Type | Internal DDS-2 (4 mm DAT) tape drive |
| Interface | SCSI |
| Compatible | Apple Workgroup Server 8150, Apple Workgroup Server 9150, Apple Workgroup Server 95, Apple Workgroup Server 80 |
| Model | 661-0039 (service part, Workgroup Server 8150) |
| Media | MRS DDS cassettes: 60 m and 90 m DDS, 120 m DDS-2 |
The Apple DAT Drive is the internal 4 mm digital audio tape (DAT) backup drive that Apple fitted to its Workgroup Servers. Apple's specification article identifies the drive in the Workgroup Server 8150 and 9150 as Hewlett-Packard's model C1533A, a DDS-2 drive.[1] Apple's support articles also cover the DAT drive in the Workgroup Server 95 and 80.[2][3] In the Workgroup Server 8150 the drive sits in the lowest front bay, on the external SCSI bus with ID 2 reserved for it, and Apple's service part number for it is 661-0039.[4][5]
The drive compresses data and corrects errors itself. Apple's guide uses Retrospect Remote, or another backup utility, to run backups and restores.[4]
Specifications
[edit | edit source]| Item | Value |
|---|---|
| Drive | Hewlett-Packard C1533A, DDS-2 |
| Capacity, 60 m DDS-1 tape | 2.6 GB typical |
| Capacity, 90 m DDS-1 tape | 4.0 GB typical |
| Capacity, 120 m DDS-2 tape | 8.0 GB typical |
| Sustained transfer rate | 510 KB/s native; 1.0 MB/s typical and 1.5 MB/s maximum with compression |
| Burst transfer rate | 3.0 MB/s asynchronous, 7.5 MB/s synchronous (maximum) |
Apple notes that the capacity depends on how well the data compresses: text compresses better than applications.[1] The Workgroup Server 8150/110 administrator's guide gives the supplied blank tape a maximum of 10 to 14 GB of compressed data.[4]
Tapes
[edit | edit source]The drive needs Media Recognition System (MRS) DDS cassettes. They carry the MRS marking, an insignia followed by four bars, and the 120 m length needs the DDS-2 rating. Apple's only qualified tape was the MRS DDS-2 cassette.[6][4]
- The drive reads non-MRS tapes but will not write to them. If backups fail with write errors, check the tape type first.[6]
- Audio DAT cassettes have a different mechanical specification from DDS data cassettes, although some vendors sell DDS cassettes as "DAT". Use only MRS data cassettes.[4]
- Apple gives MRS tapes a life of about 50 to 60 hours of use, after which they should be replaced.[7]
- Slide the tab on the back of a cassette so that the hole shows to lock it; the drive can then read it but not write to it.[4]
- Use tapes between 5 °C and 40 °C (40-104 °F). A tape that has been outside that range needs at least two hours at operating temperature first, and data should not be transferred while the temperature is changing by more than about 5 °C (10 °F) an hour. Do not leave cassettes in a car in sunshine.[4]
Status lights
[edit | edit source]The two lights beside the slot are the tape light on the left and the clean light on the right. At start-up the drive runs a self-test: both lights show solid green, then the left one flashes green and the right one goes out. With no tape loaded both then go out; with a tape loaded the left light stays green. Loading a cassette takes about 30 seconds while the drive threads and rewinds the tape.[4]
| Tape light (left) | Clean light (right) | Meaning |
|---|---|---|
| Flashing green (half-second) | Off | Cassette loading or unloading, or self-test in progress |
| Fast flashing green (quarter-second) | Off | Cassette loaded, reading or writing |
| Green | Off | Cassette loaded, drive on line |
| Any | Flashing amber | Media wear, or the heads need cleaning |
| Any | Amber | Error |
Apple's article for the Workgroup Server 95 and 80 uses a fuller table in which a steady amber left light means a write-protected cassette. Among the error states it lists:[2]
- Green left, pulsing amber right: media wear (caution).
- Amber left, amber right: high humidity, or no termination on the SCSI bus.
- Pulsing amber left, pulsing amber right: self-test running (normal).
- Pulsing amber left, amber right: self-test failure.
- Other combinations, such as either light lit while the other shows a state the table does not allow, are illegal states and indicate an error.
Cleaning
[edit | edit source]Clean the heads with a DDS cleaning cassette after every 25 hours of running time. The drive loads the cleaning cassette, cleans and ejects it by itself. Keep count of its uses and replace it after 25. Apple's rule of thumb is a weekly clean for daily backups and a monthly clean for weekly backups.[4] After every 25 hours of use, the drive shows the media-wear light pattern (left steady green, right pulsing amber) even with no tape loaded, until a cleaning cassette is run.[8] A caution signal is most often dirty heads: clean them and reinsert the tape. If it persists with a particular tape, copy the data to a new tape and discard the old one.[4]
Apple's article for the Apple Network Server gives HP's part number for its 4 mm DDS cleaning tapes as 922-83k, a two-pack.[9]
Faults
[edit | edit source]Stuck tapes
[edit | edit source]Check the lights first; they may be showing an error condition.[7] To force a tape out, hold the eject button for at least 5 seconds after the server has started. The drive waits 35 seconds for a normal eject, then unthreads the tape and ejects it. Apple warns that forcing an eject while the drive is busy can lose data or leave the tape wrongly formatted.[4]
Apple's article on stuck tapes adds:[7]
- Some early Workgroup Server 95 systems would not eject tapes because the DAT drive was out of line with the front bezel, a manufacturing fault.
- A broken tape, with no tension on it, usually means the mechanism did not seat the cassette fully before starting its motors. Two fingers in the cassette lock the hubs in storage; if the cassette covers do not open fully, the fingers stay in the hub teeth, and the tape snags and snaps when the motors tension it. To recover the cassette, shut down the server, disconnect the SCSI cable from the DAT drive, start the server, and press in on the cassette while pressing the eject button.
- If the drive fails to sense the end of the tape on every tape, the drive is faulty. If it happens only sometimes, suspect a stiff cassette that does not seat fully, or a faulty mechanism.
Condensation
[edit | edit source]When the drive detects condensation, both lights go solid amber, any command in progress is cancelled, further tape commands are refused, and the drive unthreads the tape to protect it and the heads.[4]
Self-test failure
[edit | edit source]A flashing amber right light after the self-test may mean the heads need cleaning or, with a tape loaded, a worn tape. A solid amber right light means the self-test failed; Apple's advice was not to use the drive and to take it to a service provider.[4]
A/UX
[edit | edit source]Under A/UX on the Workgroup Server 95, the tc tape driver must be accessed in 8K blocks, so tar needs a blocking factor of 16, for example tar -cvfb /dev/rmt/tc2 16 file; without it, tar gives tape write and read errors.[3] A later tc driver added support for HP's DAT-2 drive and fixed two faults: the Workgroup Server 95's DAT drive not supporting multiple files on a tape, and tapes that could not be reformatted with mt or Retrospect.[10]
Removing the drive
[edit | edit source]In the Workgroup Server 8150, take off the top housing, disconnect the SCSI data cable and the power cable from the back of the drive, press down the retaining clip and slide the drive out. Apple's instruction for a drive going back for exchange was to take it out of its carrier first.[5] Wear a grounding wrist strap.[5]
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Related pages
[edit | edit source]- Apple Workgroup Server 8150
- Apple Workgroup Server 9150
- Apple Workgroup Server 95
- Apple Network Server 500 and 700 General Maintenance
- Workgroup Server 8150 Administrator's Guide
References
[edit | edit source]- ↑ 1.0 1.1 1.2 Apple Computer, "Workgroup Server 8150 & 9150: DAT Drive Specifications (1/96)", Tech Info Library article 16138, created 30 August 1994, revised 9 January 1996, in the archive.org collection Apple's Technical Information Library Articles, https://archive.org/details/APPLE_TIL_ARTICLES, file TIL00001_to_TIL60496.zip. Source for the HP C1533A DDS-2 drive, the media it takes, the capacities and the transfer rates.
- ↑ 2.0 2.1 Apple Computer, "Apple Workgroup Server (AWS): DAT Status Lights (8/95)", Tech Info Library article 18365, created 11 August 1995, APPLE_TIL_ARTICLES collection (archive.org), file TIL00001_to_TIL60496.zip.
- ↑ 3.0 3.1 Apple Computer, "AWS 95: Using tar with DAT Tape Drive (10/96)", Tech Info Library article 16580, created 21 October 1994, revised 15 October 1996, APPLE_TIL_ARTICLES collection (archive.org), file TIL00001_to_TIL60496.zip.
- ↑ 4.00 4.01 4.02 4.03 4.04 4.05 4.06 4.07 4.08 4.09 4.10 4.11 4.12 4.13 Apple Computer, Administrator's Guide for the Workgroup Server 8150/110 (1995), hosted as File:Workgroup Server 8150-110 Administrator's Guide.pdf and described at Workgroup Server 8150 Administrator's Guide. Printed p. 35 (PDF p. 51): the DAT drive on the external SCSI bus with ID 2 reserved; chapter 5, "Using a DAT Drive and Tape Cassettes", pp. 49-54 (PDF pp. 65-70): compression and error correction, Retrospect Remote, MRS DDS cassettes and DDS-2 for 120 m, audio DAT cassettes, supplied tapes, self-test, loading, status lights, caution signal, forced eject, locking, humidity and temperature, head cleaning.
- ↑ 5.0 5.1 5.2 Apple Computer, Power Macintosh 8100/WS 8150 Service Source, hosted as File:Powermac_8100.ws_8150.pdf and described at Power Macintosh 8100/ WS 8150 Service Source. Take Apart, "Tape Drive", pp. 10-12 (PDF pp. 70-72): disconnect the SCSI data and power cables, press down the retaining clip and slide the drive out; remove the drive from its carrier before returning it to Apple. Exploded view (PDF p. 130): tape drive 661-0039.
- ↑ 6.0 6.1 Apple Computer, "Apple DAT Drive: Use Media Recognition System Tape Cart. (4/97)", Tech Info Library article 12119, created 14 May 1993, revised 23 April 1997, APPLE_TIL_ARTICLES collection (archive.org), file TIL00001_to_TIL60496.zip.
- ↑ 7.0 7.1 7.2 Apple Computer, "Workgroup Servers: Causes of Stuck DAT Tapes (10/94)", Tech Info Library article 16451, created 6 October 1994, APPLE_TIL_ARTICLES collection (archive.org), file TIL00001_to_TIL60496.zip.
- ↑ Apple Computer, "Apple WorkGroup Server: Meaning of DAT drive LEDs (2/95)", Tech Info Library article 17128, created 6 February 1995, APPLE_TIL_ARTICLES collection (archive.org), file TIL00001_to_TIL60496.zip.
- ↑ Apple Computer, "Apple Network Server: Getting More DDS Cleaning Tapes (10/96)", Tech Info Library article 20607, created 31 October 1996, APPLE_TIL_ARTICLES collection (archive.org), file TIL00001_to_TIL60496.zip.
- ↑ Apple Computer, "AWS 95 & A/UX: New Version of 'tc' For DAT-2 Drives (4/95)", Tech Info Library article 17670, created 28 April 1995, APPLE_TIL_ARTICLES collection (archive.org), file TIL00001_to_TIL60496.zip.