/DENSITY=what? for Ultrium tapes on 8.3 Alpha? - VMS

This is a discussion on /DENSITY=what? for Ultrium tapes on 8.3 Alpha? - VMS ; VMSers -- Just got an MSL4048, which has Ultrium LTO4 (1.6 tb per cartridge) drives. If I init a tape, should I just let it sit at default density? None of the options in help init/density look really good - ...

+ Reply to Thread
Results 1 to 8 of 8

Thread: /DENSITY=what? for Ultrium tapes on 8.3 Alpha?

  1. /DENSITY=what? for Ultrium tapes on 8.3 Alpha?

    VMSers --

    Just got an MSL4048, which has Ultrium LTO4 (1.6 tb per cartridge) drives.
    If I init a tape, should I just let it sit at default density? None of the
    options in help init/density look really good - SDLT320 is the highest. Would
    that match?

    VMS 8.3 on Alpha, 8.31h1 on Itanium.

    Thanks!

    -- Alan


  2. Re: /DENSITY=what? for Ultrium tapes on 8.3 Alpha?

    Alan Winston - SSRL Central Computing wrote:
    >
    > VMSers --
    >
    > Just got an MSL4048, which has Ultrium LTO4 (1.6 tb per cartridge) drives.
    > If I init a tape, should I just let it sit at default density? None of the
    > options in help init/density look really good - SDLT320 is the highest. Would
    > that match?
    >
    > VMS 8.3 on Alpha, 8.31h1 on Itanium.


    Do LTOs do multiple densities like the later TZ8xes did?

    ....or are they like the newer (S)DLT drives: write native, read(-only)
    previous? (That is, a SDLT-320 drive will read/write SDLT-320, but will
    only read SDLT-220, not write it.)

    My suggestions would be to leave /DENSITY out (use the default selected
    by the drive for the media) and choose between whether or not to use
    /MEDIA=COMPACT.

    My $0.02...

    D.J.D.

  3. Re: /DENSITY=what? for Ultrium tapes on 8.3 Alpha?

    In article <4823ADDB.493A3625@spam.comcast.net>, David J Dachtera writes:
    >Alan Winston - SSRL Central Computing wrote:
    >>
    >> VMSers --
    >>
    >> Just got an MSL4048, which has Ultrium LTO4 (1.6 tb per cartridge) drives.
    >> If I init a tape, should I just let it sit at default density? None of the
    >> options in help init/density look really good - SDLT320 is the highest. Would
    >> that match?
    >>
    >> VMS 8.3 on Alpha, 8.31h1 on Itanium.

    >
    >Do LTOs do multiple densities like the later TZ8xes did?
    >
    >...or are they like the newer (S)DLT drives: write native, read(-only)
    >previous? (That is, a SDLT-320 drive will read/write SDLT-320, but will
    >only read SDLT-220, not write it.)
    >
    >My suggestions would be to leave /DENSITY out (use the default selected
    >by the drive for the media) and choose between whether or not to use
    >/MEDIA=COMPACT.
    >
    >My $0.02...


    That was what I decided to go with, at least until I got a response.

    Seem to have completed a backup with that, so I think it's okay.

    -- Alan

  4. Re: /DENSITY=what? for Ultrium tapes on 8.3 Alpha?

    Alan Winston - SSRL Central Computing wrote:
    > In article <4823ADDB.493A3625@spam.comcast.net>, David J Dachtera writes:
    >> Alan Winston - SSRL Central Computing wrote:
    >>> VMSers --
    >>>
    >>> Just got an MSL4048, which has Ultrium LTO4 (1.6 tb per cartridge) drives.
    >>> If I init a tape, should I just let it sit at default density? None of the
    >>> options in help init/density look really good - SDLT320 is the highest. Would
    >>> that match?
    >>>
    >>> VMS 8.3 on Alpha, 8.31h1 on Itanium.

    >> Do LTOs do multiple densities like the later TZ8xes did?
    >>
    >> ...or are they like the newer (S)DLT drives: write native, read(-only)
    >> previous? (That is, a SDLT-320 drive will read/write SDLT-320, but will
    >> only read SDLT-220, not write it.)
    >>
    >> My suggestions would be to leave /DENSITY out (use the default selected
    >> by the drive for the media) and choose between whether or not to use
    >> /MEDIA=COMPACT.
    >>
    >> My $0.02...

    >
    > That was what I decided to go with, at least until I got a response.
    >
    > Seem to have completed a backup with that, so I think it's okay.
    >
    > -- Alan


    Can you read the tape? If you have not tested your ability to restore a
    backup, what is your backup worth?

  5. Re: /DENSITY=what? for Ultrium tapes on 8.3 Alpha?

    In article , "Richard B. Gilbert" writes:
    >Alan Winston - SSRL Central Computing wrote:
    >> In article <4823ADDB.493A3625@spam.comcast.net>, David J Dachtera writes:
    >>> Alan Winston - SSRL Central Computing wrote:
    >>>> VMSers --
    >>>>
    >>>> Just got an MSL4048, which has Ultrium LTO4 (1.6 tb per cartridge) drives.
    >>>> If I init a tape, should I just let it sit at default density? None of the
    >>>> options in help init/density look really good - SDLT320 is the highest. Would
    >>>> that match?
    >>>>
    >>>> VMS 8.3 on Alpha, 8.31h1 on Itanium.
    >>> Do LTOs do multiple densities like the later TZ8xes did?
    >>>
    >>> ...or are they like the newer (S)DLT drives: write native, read(-only)
    >>> previous? (That is, a SDLT-320 drive will read/write SDLT-320, but will
    >>> only read SDLT-220, not write it.)
    >>>
    >>> My suggestions would be to leave /DENSITY out (use the default selected
    >>> by the drive for the media) and choose between whether or not to use
    >>> /MEDIA=COMPACT.
    >>>
    >>> My $0.02...

    >>
    >> That was what I decided to go with, at least until I got a response.
    >>
    >> Seem to have completed a backup with that, so I think it's okay.
    >>
    >> -- Alan

    >
    >Can you read the tape? If you have not tested your ability to restore a
    >backup, what is your backup worth?


    Yes, I can. (BACKUP/LIST whizzes past too fast to read; it's pretty cool.)

    Thanks for asking!

    -- Alan


  6. Re: /DENSITY=what? for Ultrium tapes on 8.3 Alpha?

    Alan Winston - SSRL Central Computing wrote:

    > Just got an MSL4048, which has Ultrium LTO4 (1.6 tb per cartridge) drives.
    > If I init a tape, should I just let it sit at default density? None of the
    > options in help init/density look really good - SDLT320 is the highest. Would
    > that match?


    LTO is supposed to be able to write one lower and read one or
    two lower. Drives know which type of cartridge is inserted,
    and will write appropriate for that cartridge.

    You can't write a density different from the cartridge design.

    -- glen


  7. Re: /DENSITY=what? for Ultrium tapes on 8.3 Alpha?

    In article <4823ADDB.493A3625@spam.comcast.net>,
    David J Dachtera wrote:

    > Alan Winston - SSRL Central Computing wrote:
    > >
    > > VMSers --
    > >
    > > Just got an MSL4048, which has Ultrium LTO4 (1.6 tb per cartridge) drives.
    > > If I init a tape, should I just let it sit at default density? None of the
    > > options in help init/density look really good - SDLT320 is the highest.
    > > Would
    > > that match?
    > >
    > > VMS 8.3 on Alpha, 8.31h1 on Itanium.

    >
    > Do LTOs do multiple densities like the later TZ8xes did?
    >
    > ...or are they like the newer (S)DLT drives: write native, read(-only)
    > previous? (That is, a SDLT-320 drive will read/write SDLT-320, but will
    > only read SDLT-220, not write it.)
    >
    > My suggestions would be to leave /DENSITY out (use the default selected
    > by the drive for the media) and choose between whether or not to use
    > /MEDIA=COMPACT.
    >


    Not sure if this is still true, but back in the V7.n era we found that
    to ensure compression with DLT drives, we had to use
    /MEDIA_FORMAT=[NO]COMPACTION on the full combination of INIT, MOUNT and
    BACKUP commands, or the backup could revert to NOCOMPACTION.

    --
    Paul Sture

    Sue's OpenVMS bookmarks:
    http://eisner.encompasserve.org/~stu...bookmarks.html

  8. Re: /DENSITY=what? for Ultrium tapes on 8.3 Alpha?

    In article , "P. Sture" writes:
    >
    > Not sure if this is still true, but back in the V7.n era we found that
    > to ensure compression with DLT drives, we had to use
    > /MEDIA_FORMAT=[NO]COMPACTION on the full combination of INIT, MOUNT and
    > BACKUP commands, or the backup could revert to NOCOMPACTION.
    >

    TLZ04 and TLZ06 (at least) can change the compaction setting between
    files. That's considered odd behavior (not a feature), but is real
    behavior.

    Not knowing it's implementation, I suspect, but have never tested,
    it might be able to change compaction settings between physical
    blocks. Obviously INIT and BACKUP don't change that setting during
    a single operation. That could ruin your day.


+ Reply to Thread