Reading non-VMS DAT tape - VMS

This is a discussion on Reading non-VMS DAT tape - VMS ; I have an old 4mm DAT tape that was made on a PC using Novaback about ten years ago. I also have a running Alphaserver 1000 4/200 with a working DAT drive (I've read VMS format tapes with it). Does ...

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  1. Reading non-VMS DAT tape

    I have an old 4mm DAT tape that was made on a PC using Novaback about
    ten years ago. I also have a running Alphaserver 1000 4/200 with a
    working DAT drive (I've read VMS format tapes with it).

    Does anyone know a way to pull data of a 4mm DAT tape that was made on
    a PC?

    Also, what is the simplest way to backup the system disk onto a DAT
    tape?

    Thanks!

    Ron


  2. Re: Reading non-VMS DAT tape

    In article <1187671475.213273.65550@j4g2000prf.googlegroups.co m>, rtk writes:
    > I have an old 4mm DAT tape that was made on a PC using Novaback about
    > ten years ago. I also have a running Alphaserver 1000 4/200 with a
    > working DAT drive (I've read VMS format tapes with it).
    >
    > Does anyone know a way to pull data of a 4mm DAT tape that was made on
    > a PC?


    You can mount the tape /foreign and read the blocks to a file
    with COPY. But what's in those blocks may not be trivial, and you
    may have a hard time figuring out how Novaback stored disk data on
    tape (did it just copy the FAT table, how did it copy directory
    entries, ...). Also, Novaback may or may not have made multiple
    physical files so multiple COPY commands may be needed to get all
    the blocks off tape.

    IMHO I'd use a few search engines to search for Novaback and see if
    you can dig up some information on its tape format and/or the
    people who might know.

    > Also, what is the simplest way to backup the system disk onto a DAT
    > tape?


    The simplest way is to log in as SYSTEM and do a BACKUP/IMAGE.

    Better ways include using standalone BACKUP so that you know there
    are no open files on the system disk and including /VERIFY so that
    you know the tape copy is good. I generally also increase the block
    size to at least 16K (16384) when using any kind of tape.


  3. Re: Reading non-VMS DAT tape

    In article <+I6oBMvM02TO@eisner.encompasserve.org>, koehler@eisner.nospam.encompasserve.org (Bob Koehler) writes:
    >In article <1187671475.213273.65550@j4g2000prf.googlegroups.co m>, rtk writes:
    >> I have an old 4mm DAT tape that was made on a PC using Novaback about
    >> ten years ago. I also have a running Alphaserver 1000 4/200 with a
    >> working DAT drive (I've read VMS format tapes with it).
    >>
    >> Does anyone know a way to pull data of a 4mm DAT tape that was made on
    >> a PC?

    >
    > You can mount the tape /foreign and read the blocks to a file
    > with COPY. But what's in those blocks may not be trivial, and you
    > may have a hard time figuring out how Novaback stored disk data on
    > tape (did it just copy the FAT table, how did it copy directory
    > entries, ...). Also, Novaback may or may not have made multiple
    > physical files so multiple COPY commands may be needed to get all
    > the blocks off tape.
    >
    > IMHO I'd use a few search engines to search for Novaback and see if
    > you can dig up some information on its tape format and/or the
    > people who might know.
    >
    >> Also, what is the simplest way to backup the system disk onto a DAT
    >> tape?

    >
    > The simplest way is to log in as SYSTEM and do a BACKUP/IMAGE.
    >

    Since there will be open files on the system disk if you are not prepared to
    shutdown the system to do a standalone backup then use the /ignore=interlock
    command with backup/image ie

    backup/image/ignore=interlock

    This will backup the contents of opened files whereas without this the open
    files would not be backed up which will leave you with a pretty poor backup.
    Generally using /ignore=interlock is reasonably safe since most of the open
    files on the system disk are just being read from rather than being written
    to. (The only problems I have ever had restoring such a backup was once with
    the queue database getting corrupted).

    Another alternative which is often used in order to avoid shutting down the
    system is to shadow the system disk and then split the shadowset and back up
    the removed member.


    David Webb
    Security team leader
    CCSS
    Middlesex University


    > Better ways include using standalone BACKUP so that you know there
    > are no open files on the system disk and including /VERIFY so that
    > you know the tape copy is good. I generally also increase the block
    > size to at least 16K (16384) when using any kind of tape.
    >


  4. Re: Reading non-VMS DAT tape

    rtk wrote:
    >
    > I have an old 4mm DAT tape that was made on a PC using Novaback about
    > ten years ago. I also have a running Alphaserver 1000 4/200 with a
    > working DAT drive (I've read VMS format tapes with it).
    >
    > Does anyone know a way to pull data of a 4mm DAT tape that was made on
    > a PC?


    As you might expect, the answer is: it depends.

    Getting the data off the tape is semi-trivial:

    $ MOUNT/FOREIGN ddcu: ! MOUNT the tape drive
    $ COPY ddcu: 4MM_TAPE.DAT ! Copy what's on it
    $ DISMOUNT ddcu: ! DISMOUNT the tape drive - done

    ....as others have posted.

    Also, as others have posted, having the data is one matter - interpreting it to
    restore its content to being something meaningful is another matter entirely.

    > Also, what is the simplest way to backup the system disk onto a DAT
    > tape?


    The same as it would be for any magtape medium. See the VMS docset for examples
    and guidance.

    --
    David J Dachtera
    dba DJE Systems
    http://www.djesys.com/

    Unofficial OpenVMS Marketing Home Page
    http://www.djesys.com/vms/market/

    Unofficial Affordable OpenVMS Home Page:
    http://www.djesys.com/vms/soho/

    Unofficial OpenVMS-IA32 Home Page:
    http://www.djesys.com/vms/ia32/

    Unofficial OpenVMS Hobbyist Support Page:
    http://www.djesys.com/vms/support/

  5. Re: Reading non-VMS DAT tape

    Thanks for all the helpful replies!

    I tried reading the tape as suggested and received an error about end
    of file (or similar) and nothing was read. So, I decided to just
    trash the tape and use it to back up the system disk. I booted the
    Hobbyist CD and went to DCL and did something along these lines:

    $$$ mount dka0:
    $$$ mount/foreign mka300:
    $$$ backup/image/verify dka0: mka300:22_aug_07.bck/save_set

    and it appears to be working, though I'm not sure this is exactly what
    I want. I got an error about the tape label and chose the OVERWRITE
    option. Doing this:

    $$$ backup/image/verify dka0: mka300:

    save me an error about requiring a save set name. But, if I need to
    restore my system disk at some future point I should be able to do it
    from the save set after booting the Hobbyist CD, correct?

    Ron


  6. Re: Reading non-VMS DAT tape

    In article <1187788620.290336.110930@q4g2000prc.googlegroups.c om>, rtk writes:
    > Thanks for all the helpful replies!
    >
    > I tried reading the tape as suggested and received an error about end
    > of file (or similar) and nothing was read.


    Magnetic tape drives, including DAT drives emulate 9 track mag tape.

    The data on the emulated media consists of blocks and tape marks.

    [On 9 track, a block was a bunch of data written on parallel
    tracks (8 bits plus parity) at, for instance, 1600 bits per inch.
    So a 512 byte block would be about 1/3 of an inch of tape. Between
    each block you would have an "inter-record gap" which was somewhere
    around 1/2 of an inch long (the size could vary) and allowed room
    for the tape to slow down to a stop after processing one block and
    speed back up before processing the next one. I've never been
    clear on how a "tape mark" was encoded on 9 track tape]

    A block is just a block of data. On VMS it will be limited to
    65534 bytes or so. Most tapes are written with block sizes far
    less than this.

    A tape mark is a special pattern on the tape. It is distinguishable
    from a block and is usually treated as end of file.

    So if you:

    $ MOUNT MKA300: /BLOCK=65534 ! Be sure to specify a block size
    ! at least as large as the largest block
    ! you expect on the tape. Failure to
    ! do this can result in "data overrun"
    $ COPY /LOG MKA300: FILE1.DAT
    %COPY-I-COPIED, 3 records copied
    $

    What you'll get in FILE1.DAT is one record for each block on the tape
    up to the position of the first tape mark.

    To get the next file on the tape, you would repeat the COPY:

    $ COPY /LOG MKA300: FILE2.DAT
    %COPY-I-COPIED, 56712 records copied

    And repeat...

    $ COPY /LOG MKA300: FILE3.DAT
    %COPY-I-COPIED, 3 records copied
    $ COPY /LOG MKA300: FILE4.DAT
    %COPY-I-COPIED, 0 records copied
    $ COPY /LOG MKA300: FILE5.DAT
    -- parity error --

    This last is a clue. The standard "end of volume" indication on
    a reel of magnetic tape is two back-to-back tape marks. This looks
    just like an empty file. You usually want to stop reading from the
    tape once you've hit that "0 records copied" file.

    [In the case of labelled mag tape, back-to-back tape marks that
    enclose an empty file are treated differently from back to back tape
    marks that follow an EOV label, so it isn't always guaranteed to
    be the case that back to back tape marks indicate end of volume]

    Often, magnetic tape data is stored in a labelled format. The first
    "file" on the tape isn't a file at all, but is, instead, a short series
    of blocks describing the data that follows. Standard labelling schemes
    put labels both before and after every file and at the start and end
    of every reel in a multi-reel volume set.

    ANSI and IBM standard labels are stored in 80 byte blocks using ASCII
    (for ANSI labels) or EBCDIC (for IBM labels) text in the labels. This
    was very true historically, but I have no idea what kind of labelling
    scheme (if any) is used by modern PC backup programs.

    > So, I decided to just
    > trash the tape and use it to back up the system disk. I booted the
    > Hobbyist CD and went to DCL and did something along these lines:


    I guess it's trash now and the above explanation is largely useless.

    For your information, VMS BACKUPs are stored using the ANSI labelling
    convention.

    > $$$ mount dka0:
    > $$$ mount/foreign mka300:
    > $$$ backup/image/verify dka0: mka300:22_aug_07.bck/save_set


    > and it appears to be working, though I'm not sure this is exactly what
    > I want. I got an error about the tape label and chose the OVERWRITE
    > option. Doing this:
    >
    > $$$ backup/image/verify dka0: mka300:
    >
    > save me an error about requiring a save set name. But, if I need to
    > restore my system disk at some future point I should be able to do it
    > from the save set after booting the Hobbyist CD, correct?


    Try:

    $ BACKUP /REWIND /IMAGE /VERIFY DKA0: MKA300:mysaveset.bck

    You can have multiple save sets per tape.

    You probably want to specify /REWIND to make sure that your backup
    starts at the beginning of the tape, overwriting any previous data
    and tape labels.

    [It would be embarrassing to restore from the oldest save set
    on a tape with three identically named save sets and not realize
    that you were running from a 2 month old backup instead of something
    current. It's also painful to wait for the drive to skip over huge
    save sets on its way to finding the one you're after]

  7. Re: Reading non-VMS DAT tape

    On Aug 22, 8:03 am, bri...@encompasserve.org wrote:
    > I guess it's trash now and the above explanation is largely useless.


    Nope, it isn't. I have another DAT tape, plus my brother has a few he
    might want read. Thanks, this is helpful. That tape was written on a
    Macintosh, so heaven knows how it might be formatted.

    Also, thanks for the help on how to make the backup. I think I'll
    start again once this one finishes and do as you suggested to make
    sure it is a useful backup. The drive is 2.1GB in size, I hope that
    fits on one tape.

    Ron


  8. Re: Reading non-VMS DAT tape

    On Aug 22, 9:17 am, rtk wrote:
    > Thanks for all the helpful replies!
    >
    > I tried reading the tape as suggested and received an error about end
    > of file (or similar) and nothing was read. So, I decided to just
    > trash the tape and use it to back up the system disk. I booted the
    > Hobbyist CD and went to DCL and did something along these lines:
    >
    > $$$ mount dka0:
    > $$$ mount/foreign mka300:
    > $$$ backup/image/verify dka0: mka300:22_aug_07.bck/save_set
    >
    > and it appears to be working, though I'm not sure this is exactly what
    > I want. I got an error about the tape label and chose the OVERWRITE
    > option. Doing this:
    >
    > $$$ backup/image/verify dka0: mka300:
    >
    > save me an error about requiring a save set name. But, if I need to
    > restore my system disk at some future point I should be able to do it
    > from the save set after booting the Hobbyist CD, correct?
    >
    > Ron


    No save set name?! Make sure each save set on the same tape has a
    different name. Otherwise you will get a mismatch during the verify
    pass! And you'll have trouble selecting a save set, of course.

    Why the triple dollar signs?

    AEF


  9. Re: Reading non-VMS DAT tape

    In article <1187788620.290336.110930@q4g2000prc.googlegroups.c om>, rtk writes:
    >
    > save me an error about requiring a save set name. But, if I need to
    > restore my system disk at some future point I should be able to do it
    > from the save set after booting the Hobbyist CD, correct?


    Yes. You can mount the tape as a labeled tape (not /foreign) and
    get a DIRECTORY listing of the saveset name if you didn't write it
    on the tape.

  10. Re: Reading non-VMS DAT tape

    In article , koehler@eisner.nospam.encompasserve.org (Bob Koehler) writes:
    > In article <1187788620.290336.110930@q4g2000prc.googlegroups.c om>, rtk writes:
    >>
    >> save me an error about requiring a save set name. But, if I need to
    >> restore my system disk at some future point I should be able to do it
    >> from the save set after booting the Hobbyist CD, correct?

    >
    > Yes. You can mount the tape as a labeled tape (not /foreign) and
    > get a DIRECTORY listing of the saveset name if you didn't write it
    > on the tape.


    If it's the first (or only) save set on the tape, you can also
    do the restore without a save set name:

    $ BACKUP /IMAGE MKA300: DKA0:

    By default, a restore operation will pick the first [or next if you're
    already in the middle of the tape] save set from the tape.

  11. Re: Reading non-VMS DAT tape

    rtk wrote:
    >
    > Thanks for all the helpful replies!
    >
    > I tried reading the tape as suggested and received an error about end
    > of file (or similar) and nothing was read. So, I decided to just
    > trash the tape and use it to back up the system disk. I booted the
    > Hobbyist CD and went to DCL and did something along these lines:
    >
    > $$$ mount dka0:
    > $$$ mount/foreign mka300:
    > $$$ backup/image/verify dka0: mka300:22_aug_07.bck/save_set
    >
    > and it appears to be working, though I'm not sure this is exactly what
    > I want. I got an error about the tape label and chose the OVERWRITE
    > option. Doing this:
    >
    > $$$ backup/image/verify dka0: mka300:
    >
    > save me an error about requiring a save set name. But, if I need to
    > restore my system disk at some future point I should be able to do it
    > from the save set after booting the Hobbyist CD, correct?


    Correct.

    Backup expects a saveset name because the default for magtape media is to
    write/read a saveset, and there is no way to over-ride that.

    --
    David J Dachtera
    dba DJE Systems
    http://www.djesys.com/

    Unofficial OpenVMS Marketing Home Page
    http://www.djesys.com/vms/market/

    Unofficial Affordable OpenVMS Home Page:
    http://www.djesys.com/vms/soho/

    Unofficial OpenVMS-IA32 Home Page:
    http://www.djesys.com/vms/ia32/

    Unofficial OpenVMS Hobbyist Support Page:
    http://www.djesys.com/vms/support/

  12. Re: Reading non-VMS DAT tape

    rtk wrote:
    >
    > On Aug 22, 8:03 am, bri...@encompasserve.org wrote:
    > > I guess it's trash now and the above explanation is largely useless.

    >
    > Nope, it isn't. I have another DAT tape, plus my brother has a few he
    > might want read. Thanks, this is helpful. That tape was written on a
    > Macintosh, so heaven knows how it might be formatted.
    >
    > Also, thanks for the help on how to make the backup. I think I'll
    > start again once this one finishes and do as you suggested to make
    > sure it is a useful backup. The drive is 2.1GB in size, I hope that
    > fits on one tape.


    A note of caution about 4mm/DAT - it stretches REAL easy! Handle with care
    always, and don't use for archival storage.

    --
    David J Dachtera
    dba DJE Systems
    http://www.djesys.com/

    Unofficial OpenVMS Marketing Home Page
    http://www.djesys.com/vms/market/

    Unofficial Affordable OpenVMS Home Page:
    http://www.djesys.com/vms/soho/

    Unofficial OpenVMS-IA32 Home Page:
    http://www.djesys.com/vms/ia32/

    Unofficial OpenVMS Hobbyist Support Page:
    http://www.djesys.com/vms/support/

  13. Re: Reading non-VMS DAT tape

    AEF wrote:
    >
    > On Aug 22, 9:17 am, rtk wrote:
    > > Thanks for all the helpful replies!
    > >
    > > I tried reading the tape as suggested and received an error about end
    > > of file (or similar) and nothing was read. So, I decided to just
    > > trash the tape and use it to back up the system disk. I booted the
    > > Hobbyist CD and went to DCL and did something along these lines:
    > >
    > > $$$ mount dka0:
    > > $$$ mount/foreign mka300:
    > > $$$ backup/image/verify dka0: mka300:22_aug_07.bck/save_set
    > >
    > > and it appears to be working, though I'm not sure this is exactly what
    > > I want. I got an error about the tape label and chose the OVERWRITE
    > > option. Doing this:
    > >
    > > $$$ backup/image/verify dka0: mka300:
    > >
    > > save me an error about requiring a save set name. But, if I need to
    > > restore my system disk at some future point I should be able to do it
    > > from the save set after booting the Hobbyist CD, correct?
    > >
    > > Ron

    >
    > No save set name?! Make sure each save set on the same tape has a
    > different name. Otherwise you will get a mismatch during the verify
    > pass! And you'll have trouble selecting a save set, of course.
    >
    > Why the triple dollar signs?


    That's the DCL prompt in the Boot CD's "stand-alone" environment. In essence,
    it's a SPAWNed subprocess of the STARTUP process.

    In VAX-land, boot from root 1 on VMS V6.2 and later.

    In Alpha or I64 land, just boot up the CD.

    In either case, a menu of options is offered. One of the options is to execute
    commands.

    --
    David J Dachtera
    dba DJE Systems
    http://www.djesys.com/

    Unofficial OpenVMS Marketing Home Page
    http://www.djesys.com/vms/market/

    Unofficial Affordable OpenVMS Home Page:
    http://www.djesys.com/vms/soho/

    Unofficial OpenVMS-IA32 Home Page:
    http://www.djesys.com/vms/ia32/

    Unofficial OpenVMS Hobbyist Support Page:
    http://www.djesys.com/vms/support/

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