TK50 Tape Not Loading - DEC

This is a discussion on TK50 Tape Not Loading - DEC ; urbancamo skrev: > Another question I'd like to ask is if it is possible to use any of > the newer (higher density) media in a TK50 drive, possibly by > degaussing first, or whether TK50s are only compatible with ...

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Thread: TK50 Tape Not Loading

  1. Re: TK50 Tape Not Loading

    urbancamo skrev:
    > Another question I'd like to ask is if it is possible to use any of
    > the newer (higher density) media in a TK50 drive, possibly by
    > degaussing first, or whether TK50s are only compatible with Compaq
    > Tape I cartridges.
    >
    > I would be nice to be able to buy a compatible cartridge new and know
    > it has some guaranteed life (and that it wasn't going to gunk up the
    > heads at some indeterminate point).


    I seem to remember that at least TK70 tapes could be used in a TK50 if they were
    degaussed first.

    Johnny

    --
    Johnny Billquist || "I'm on a bus
    || on a psychedelic trip
    email: bqt@softjar.se || Reading murder books
    pdp is alive! || tryin' to stay hip" - B. Idol

  2. Re: TK50 Tape Not Loading

    ChrisKalisiak skrev:
    >> And no, you don't clean it by pushing something in from the front.

    >
    > Actually, as a matter of fact, that's exactly how you clean a TK50
    > with a TK50/TK70 cleaning kit.
    >
    > But few of them exist now, so it's probably not particularly relevant.
    > Just figured I'd follow up on that.


    Ah. Never seen one. Not even when I worked at DEC. The TK50 we had on the
    VAX-11/750 there was constantly open, since we needed to clean it regularly.

    > Regarding bulk erasing a TK70 to make it work in a TK50... It's
    > actually a bad idea with a DLT tape, because it nukes the servo track,
    > and then the drive is left to write its own, for better or for worse.
    > I don't know if there's a servo track on TK50/TK70 tapes. With that
    > said, TK/DLT tapes have never been backward compatible (e.g. DLT-IV
    > tapes cannot be used in a DLT2000), so it doesn't sound feasible.


    I know that there is some kind of information on the tape, since a TK50-drive
    will not accept a TK70 cartridge (and if nothing else, the head seeks that are
    performed at load is a sign that something on the tape is checked). But I seem
    to remember that bulk erasing a TK70 cartridge made it usable on a TK50.

    But I have no clue about newer cartridges.

    Johnny

    --
    Johnny Billquist || "I'm on a bus
    || on a psychedelic trip
    email: bqt@softjar.se || Reading murder books
    pdp is alive! || tryin' to stay hip" - B. Idol

  3. Re: TK50 Tape Not Loading

    On Dec 6, 7:22 pm, Johnny Billquist wrote:
    > ChrisKalisiak skrev:
    >
    > >> And no, you don't clean it by pushing something in from the front.

    >
    > > Actually, as a matter of fact, that's exactly how you clean a TK50
    > > with a TK50/TK70 cleaning kit.

    >
    > > But few of them exist now, so it's probably not particularly relevant.
    > > Just figured I'd follow up on that.

    >
    > Ah. Never seen one. Not even when I worked at DEC. The TK50 we had on the
    > VAX-11/750 there was constantly open, since we needed to clean it regularly.
    >
    > > Regarding bulk erasing a TK70 to make it work in a TK50... It's
    > > actually a bad idea with a DLT tape, because it nukes the servo track,
    > > and then the drive is left to write its own, for better or for worse.
    > > I don't know if there's a servo track on TK50/TK70 tapes. With that
    > > said, TK/DLT tapes have never been backward compatible (e.g. DLT-IV
    > > tapes cannot be used in a DLT2000), so it doesn't sound feasible.

    >
    > I know that there is some kind of information on the tape, since a TK50-drive
    > will not accept a TK70 cartridge (and if nothing else, the head seeks that are
    > performed at load is a sign that something on the tape is checked).


    The DLTTape media format specifies three areas on the tape
    right after the leader splice and before the BOT hole:
    Scratch area - set write currents, etc
    Calibration area - vertical position, azimuth, density detection
    Directory area - directory of data objects, read into the drives
    memory on load and updated at upload.
    Thats what you see the head doing, moving up and down
    on a load. Not sure what happens if errors pop up in any
    of the three areas ?

    Of course you could have a tach problem under the rear idler
    roller or a bad BOT/EOT mounted sensor right after the r/w head.
    Anything can void a tape load.

    But I seem
    > to remember that bulk erasing a TK70 cartridge made it usable on a TK50.
    >
    > But I have no clue about newer cartridges.
    >
    > Johnny
    >
    > --
    > Johnny Billquist || "I'm on a bus
    > || on a psychedelic trip
    > email: b...@softjar.se || Reading murder books
    > pdp is alive! || tryin' to stay hip" - B. Idol



  4. Re: TK50 Tape Not Loading

    On Dec 6, 10:15 pm, bob.bi...@gmail.com wrote:
    > On Dec 6, 7:22 pm, Johnny Billquist wrote:
    >
    >
    >
    > > ChrisKalisiak skrev:

    >
    > > >> And no, you don't clean it by pushing something in from the front.

    >
    > > > Actually, as a matter of fact, that's exactly how you clean a TK50
    > > > with a TK50/TK70 cleaning kit.

    >
    > > > But few of them exist now, so it's probably not particularly relevant.
    > > > Just figured I'd follow up on that.

    >
    > > Ah. Never seen one. Not even when I worked at DEC. The TK50 we had on the
    > > VAX-11/750 there was constantly open, since we needed to clean it regularly.

    >
    > > > Regarding bulk erasing a TK70 to make it work in a TK50... It's
    > > > actually a bad idea with a DLT tape, because it nukes the servo track,
    > > > and then the drive is left to write its own, for better or for worse.
    > > > I don't know if there's a servo track on TK50/TK70 tapes. With that
    > > > said, TK/DLT tapes have never been backward compatible (e.g. DLT-IV
    > > > tapes cannot be used in a DLT2000), so it doesn't sound feasible.

    >
    > > I know that there is some kind of information on the tape, since a TK50-drive
    > > will not accept a TK70 cartridge (and if nothing else, the head seeks that are
    > > performed at load is a sign that something on the tape is checked).

    >
    > The DLTTape media format specifies three areas on the tape
    > right after the leader splice and before the BOT hole:
    > Scratch area - set write currents, etc
    > Calibration area - vertical position, azimuth, density detection
    > Directory area - directory of data objects, read into the drives
    > memory on load and updated at upload.


    Typo thats "....updated at unload......"

    > Thats what you see the head doing, moving up and down
    > on a load. Not sure what happens if errors pop up in any
    > of the three areas ?
    >
    > Of course you could have a tach problem under the rear idler
    > roller or a bad BOT/EOT mounted sensor right after the r/w head.
    > Anything can void a tape load.
    >
    > But I seem
    >
    > > to remember that bulk erasing a TK70 cartridge made it usable on a TK50.

    >
    > > But I have no clue about newer cartridges.

    >
    > > Johnny

    >
    > > --
    > > Johnny Billquist || "I'm on a bus
    > > || on a psychedelic trip
    > > email: b...@softjar.se || Reading murder books
    > > pdp is alive! || tryin' to stay hip" - B. Idol



  5. Re: TK50 Tape Not Loading

    > > Regarding bulk erasing a TK70 to make it work in a TK50... It's
    > > actually a bad idea with a DLT tape, because it nukes the servo track,
    > > and then the drive is left to write its own, for better or for worse.
    > > I don't know if there's a servo track on TK50/TK70 tapes.

    >
    > No servo tracks on the TK50, 24 serpentine tracks written/read
    > one at a time forward to EOT than reverse ans stepping the head
    > down. The SDLT has an optical servo track at end of tape.


    The DLT tapes used in DLT2000/DLT2000XT/DLT4000/etc. drives have a
    magnetic servo track that's laid down by the manufacturer. Bulk
    erasing wipes out that servo track, and if a tape drive can't find the
    servo track, it lays down one on its own. The problem with that is if
    the drive that lays down the servo track is out of alignment, then the
    next drive that you try to use may not be able to read that tape.

    The intent of the optical servo track on SDLT tapes is to allow for
    denser media; it allows for more precision. And the added benefit is
    bulk erasing has no effect on the servo track.

    Chris

  6. Re: TK50 Tape Not Loading

    In article , Johnny Billquist writes:
    >
    > I seem to remember that at least TK70 tapes could be used in a TK50 if they were
    > degaussed first.
    >

    In fact, most TK50 tapes would write and read in a TK70 if you
    degaussed them first. Of course, you were writing at a higher
    density than supported and occaisionally one would fail.


  7. Re: TK50 Tape Not Loading

    On Dec 7, 8:33 am, ChrisKalisiak wrote:
    > > > Regarding bulk erasing a TK70 to make it work in a TK50... It's
    > > > actually a bad idea with a DLT tape, because it nukes the servo track,
    > > > and then the drive is left to write its own, for better or for worse.
    > > > I don't know if there's a servo track on TK50/TK70 tapes.

    >
    > > No servo tracks on the TK50, 24 serpentine tracks written/read
    > > one at a time forward to EOT than reverse ans stepping the head
    > > down. The SDLT has an optical servo track at end of tape.

    >
    > The DLT tapes used in DLT2000/DLT2000XT/DLT4000/etc. drives have a
    > magnetic servo track that's laid down by the manufacturer. Bulk
    > erasing wipes out that servo track, and if a tape drive can't find the
    > servo track, it lays down one on its own. The problem with that is if
    > the drive that lays down the servo track is out of alignment, then the
    > next drive that you try to use may not be able to read that tape.


    I'm not so sure you can call them "servo tracks" on the
    DLT2000 and 4000, if one were to compare them to a track following
    servo on a hard drive or embedded servo that positions the
    heads dynamically as the signal is read. The spec calls them
    logical blocks.

    The DLT2000/4000 dedicates two of the 128 tracks in the data area
    as "logical tracks" (not servo) and the tracks are not used to
    dynamically control the azimuth of the head. The logical blocks
    look like maps of the data on the other 126 tracks. The
    DLT 2000 still has the three areas between the leader splice
    and BOT hole for write current settings, azimuth and directory
    info. The positioning sensed in this area by the head circuitry
    dictates what or how data is read in the 128 track data
    area, similar to a HD servo technique.

    If I were to bulk erase a DLT tape I would exclude the area
    From the tape splice to the BOT.

    Perhaps the DLT2000XT spec calls for servo tracks,
    I haven't read that yet ?

    >
    > The intent of the optical servo track on SDLT tapes is to allow for
    > denser media; it allows for more precision. And the added benefit is
    > bulk erasing has no effect on the servo track.
    >
    > Chris



  8. Re: TK50 Tape Not Loading

    Ah, ok, so apparently I had the nomenclature and the form identified
    incorrectly (learn something new every day), but the function is still
    basically the same. If a DLT tape is bulk erased, that data is lost,
    and the next time the tape is loaded into a drive, the drive will
    eventually give up looking for that area and will write its own down
    onto the tape. And if that drive is out of alignment, then the tape
    might not be readable in another drive that's also out of alignment,
    but out of alignment in a different way.

    Heh, good luck telling a degausser not to bulk erase that section of
    the tape. ;-)

    Chris

  9. Re: TK50 Tape Not Loading

    On Dec 8, 7:52 am, ChrisKalisiak wrote:
    > Ah, ok, so apparently I had the nomenclature and the form identified
    > incorrectly (learn something new every day), but the function is still
    > basically the same. If a DLT tape is bulk erased, that data is lost,
    > and the next time the tape is loaded into a drive, the drive will
    > eventually give up looking for that area and will write its own down
    > onto the tape.


    One would assume thats mite happen but wud the firmware on
    the drive logic board do that or wud you have to evoke it
    using the driver in the OS. Probably the latter. A TK50 failure
    to load problem doesn't provide many clues on what is
    wrong or how to proceed.

    And if that drive is out of alignment, then the tape
    > might not be readable in another drive that's also out of alignment,
    > but out of alignment in a different way.


    Like any tape drive there is a "skew" tape and Quantum has a
    master tape to set alignment, read/write levels but I'm not
    sure it's available to the field/users. Using shims, magnesee,
    scope and a screwdriver one can improvise to get the drive
    close to perfect alignment. Been there, done that.

    >
    > Heh, good luck telling a degausser not to bulk erase that section of
    > the tape. ;-)


    Yep or use your own home made degausser, like me and a lot
    of old timers do...
    >
    > Chris



  10. Re: TK50 Tape Not Loading


    Laying down a new copy of the alignment data is handled by the drive's
    firmware. The OS doesn't know anything happened until the drive has
    either finished loading the tape or has failed to load the tape. It'd
    pretty much have to be that way; a bootloader wouldn't have enough
    intelligence to tell an MU0: to rewrite that data.

    I was being a little silly about telling a degausser not to nuke the
    alignment data -- a degausser, whether home-made or commercially
    produced -- will indescriminately destroy all magnetic information on
    the tape. I use DLT-IV tapes in my 6-drive 60-tape DLT8000 library,
    and I am sure to avoid tapes that were bulk erased, because I don't
    want to deal with the possibility that one of my drives is slightly
    misaligned. Similarly, I discard any blank tape that fails to load in
    a minute in a DLT8000, for the same basic reason.

    I'd love to get my hands on an alignment tape. They exist, but are
    rare, and when you can find them, they're expensive.

    Chris

  11. Re: TK50 Tape Not Loading

    On Dec 9, 10:06 am, ChrisKalisiak wrote:
    > Laying down a new copy of the alignment data is handled by the drive's
    > firmware. The OS doesn't know anything happened until the drive has
    > either finished loading the tape or has failed to load the tape. It'd
    > pretty much have to be that way; a bootloader wouldn't have enough
    > intelligence to tell an MU0: to rewrite that data.


    Not to belabor a point and to further my understanding of
    the DLT drive, why do you call it "alignment data" when it
    seems to me the two tracks have nothing to do with
    dynamic or static alignment of the heads. Thats done
    during load in the 3 areas prior to the BOT hole.
    Least thats what I think.
    >
    > I was being a little silly about telling a degausser not to nuke the
    > alignment data -- a degausser, whether home-made or commercially
    > produced -- will indescriminately destroy all magnetic information on
    > the tape. I use DLT-IV tapes in my 6-drive 60-tape DLT8000 library,
    > and I am sure to avoid tapes that were bulk erased, because I don't
    > want to deal with the possibility that one of my drives is slightly
    > misaligned. Similarly, I discard any blank tape that fails to load in
    > a minute in a DLT8000, for the same basic reason.


    No, the home made degausser are simple devices, like mine,
    and you just leave the begininng of the tape (or any portion)
    off the degausser and out of harms (flux changes) way.
    >
    > I'd love to get my hands on an alignment tape. They exist, but are
    > rare, and when you can find them, they're expensive.


    Yep, for some reason their always hard to find and
    if you have one, never throw it away or sell it. I still have my
    9 track tape alignment tape and my RK06 alignment pack.
    But lacking an alignment media one can still align the device
    with limited, low cost tools ;-)
    >
    > Chris



  12. Re: TK50 Tape Not Loading


    wrote in message
    news:8062d3e9-ebb3-49d8-982c-c23ad65b3445@s19g2000prg.googlegroups.com...
    > On Dec 9, 10:06 am, ChrisKalisiak wrote:
    >> Laying down a new copy of the alignment data is handled by the drive's
    >> firmware. The OS doesn't know anything happened until the drive has
    >> either finished loading the tape or has failed to load the tape. It'd
    >> pretty much have to be that way; a bootloader wouldn't have enough
    >> intelligence to tell an MU0: to rewrite that data.

    >
    > Not to belabor a point and to further my understanding of
    > the DLT drive, why do you call it "alignment data" when it
    > seems to me the two tracks have nothing to do with
    > dynamic or static alignment of the heads. Thats done
    > during load in the 3 areas prior to the BOT hole.
    > Least thats what I think.
    >>
    >> I was being a little silly about telling a degausser not to nuke the
    >> alignment data -- a degausser, whether home-made or commercially
    >> produced -- will indescriminately destroy all magnetic information on
    >> the tape. I use DLT-IV tapes in my 6-drive 60-tape DLT8000 library,
    >> and I am sure to avoid tapes that were bulk erased, because I don't
    >> want to deal with the possibility that one of my drives is slightly
    >> misaligned. Similarly, I discard any blank tape that fails to load in
    >> a minute in a DLT8000, for the same basic reason.

    >
    > No, the home made degausser are simple devices, like mine,
    > and you just leave the begininng of the tape (or any portion)
    > off the degausser and out of harms (flux changes) way.
    >>
    >> I'd love to get my hands on an alignment tape. They exist, but are
    >> rare, and when you can find them, they're expensive.

    >
    > Yep, for some reason their always hard to find and
    > if you have one, never throw it away or sell it. I still have my
    > 9 track tape alignment tape and my RK06 alignment pack.
    > But lacking an alignment media one can still align the device
    > with limited, low cost tools ;-)
    >>
    >> Chris

    >


    On your last point there, are there any good resources out there on how to
    align a device using "limited, low cost tools". I have no idea how to do
    this, and I wonder whether the device is not aligned as I know the tape I am
    trying to load has been successfully read in the last few months. I am going
    to try with someone else's tape in a couple of days to see if that works,
    but this second tape is in an unknown condition.

    Thanks

    Rob



  13. Re: TK50 Tape Not Loading

    On Dec 9, 5:51 pm, "Robert Jarratt" wrote:
    > wrote in message
    >
    > news:8062d3e9-ebb3-49d8-982c-c23ad65b3445@s19g2000prg.googlegroups.com...
    >
    >
    >
    > > On Dec 9, 10:06 am, ChrisKalisiak wrote:
    > >> Laying down a new copy of the alignment data is handled by the drive's
    > >> firmware. The OS doesn't know anything happened until the drive has
    > >> either finished loading the tape or has failed to load the tape. It'd
    > >> pretty much have to be that way; a bootloader wouldn't have enough
    > >> intelligence to tell an MU0: to rewrite that data.

    >
    > > Not to belabor a point and to further my understanding of
    > > the DLT drive, why do you call it "alignment data" when it
    > > seems to me the two tracks have nothing to do with
    > > dynamic or static alignment of the heads. Thats done
    > > during load in the 3 areas prior to the BOT hole.
    > > Least thats what I think.

    >
    > >> I was being a little silly about telling a degausser not to nuke the
    > >> alignment data -- a degausser, whether home-made or commercially
    > >> produced -- will indescriminately destroy all magnetic information on
    > >> the tape. I use DLT-IV tapes in my 6-drive 60-tape DLT8000 library,
    > >> and I am sure to avoid tapes that were bulk erased, because I don't
    > >> want to deal with the possibility that one of my drives is slightly
    > >> misaligned. Similarly, I discard any blank tape that fails to load in
    > >> a minute in a DLT8000, for the same basic reason.

    >
    > > No, the home made degausser are simple devices, like mine,
    > > and you just leave the begininng of the tape (or any portion)
    > > off the degausser and out of harms (flux changes) way.

    >
    > >> I'd love to get my hands on an alignment tape. They exist, but are
    > >> rare, and when you can find them, they're expensive.

    >
    > > Yep, for some reason their always hard to find and
    > > if you have one, never throw it away or sell it. I still have my
    > > 9 track tape alignment tape and my RK06 alignment pack.
    > > But lacking an alignment media one can still align the device
    > > with limited, low cost tools ;-)

    >
    > >> Chris

    >
    > On your last point there, are there any good resources out there on how to
    > align a device using "limited, low cost tools".


    No resources I know of other than newsgroup posters, but there must
    be a helpful web site somewhere.
    By "limited, low cost tools" I meant shims, scope, magnesee,
    screwdriver,
    etc., and some experience doing a realignment before on another device
    to
    understand what you are trying to achieve.
    An alignment is the last step, taken after you have confirmed the
    head, p/s,
    logic bd, tape path, BOT/EOT sensor, tach, etc are all a-ok and
    working.
    You don't want to possibly add another problem doing a first
    time alignment.

    I have no idea how to do
    > this, and I wonder whether the device is not aligned as I know the tape I am
    > trying to load has been successfully read in the last few months. I am going
    > to try with someone else's tape in a couple of days to see if that works,
    > but this second tape is in an unknown condition.


    Methinks if the drive were misaligned it still shud be able to write
    and
    read tapes created on itself but not from or to another drive.
    Unless during a load the bad drive cannot read/write the
    calibration/directory areas prior to the BOT hole.


    >
    > Thanks
    >
    > Rob




  14. Re: TK50 Tape Not Loading


    "Stanley F. Quayle" wrote in message
    news:976caf0f-aeb5-4c47-8892-f65d438baa54@w34g2000hsg.googlegroups.com...
    > If you can get a SCSI interface, the TZ87 (not TZ87N) drive can read
    > TK50's and read/write DLT-3. I have 6 of them to do data recovery for
    > clients.
    >
    > And there's a place in Nashua, NH that can rebuild them to factory
    > specs, including new heads and leaders, for $150. I bought several
    > TZ87's on eBay, and got them rebuilt. For a total of $200 per drive,
    > it can't be beat.
    >
    > The other advantage of the TZ87 is that you can rewind the tape using
    > a Phillips screwdriver. I've found that most TK50 tapes are sticky
    > enough that they get caught once in a while. You can't do that on the
    > smaller drives that have the left-right lever. The tape path is very
    > easy to clean, too.
    >
    > If you buy a copy of CHARON-VAX [Shameless Plug Alert (tm) -- I am a
    > CHARON-VAX reseller], you could replace this beast and read your tapes
    > with a TZ87 one time, and be done. [I don't sell TZ87's, just use
    > them]


    There is a TZ87-VA up on eBay at the moment. If this has a SCSI interface
    will VMS 7.3 running on a VAXstation 4000 VLC or a VAXstation 3100 M38 be
    able to use it?

    By the way, I have another tape now which does load, but I fear I may have
    damaged the electronics in my ham-fisted attempt to clean the heads as I can
    no longer see the device from VMS.

    Thanks

    Rob



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