Volume Shadowing Availability - VMS

This is a discussion on Volume Shadowing Availability - VMS ; Hi Guys There was a document kicking around some 10 years ago that gave a mathematical analysis of relative availability with single, two and three member shadow sets. Guess it was about 15-20 pages long. Anyone have an electronic copy ...

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  1. Volume Shadowing Availability

    Hi Guys

    There was a document kicking around some 10 years ago that gave a
    mathematical analysis of relative availability with single, two and
    three member shadow sets. Guess it was about 15-20 pages long.

    Anyone have an electronic copy or knwo where it was published?

    Thanks and regards

    -Neil


  2. Re: Volume Shadowing Availability

    Neil Lowden wrote:
    > Hi Guys
    >
    > There was a document kicking around some 10 years ago that gave a
    > mathematical analysis of relative availability with single, two and
    > three member shadow sets. Guess it was about 15-20 pages long.
    >
    > Anyone have an electronic copy or knwo where it was published?
    >
    > Thanks and regards
    >
    > -Neil
    >


    Have you tried Google? Plug in what you remember about the title,
    author, publisher, date, content, etc.


  3. Re: Volume Shadowing Availability

    > Have you tried Google? Plug in what you remember about the title,
    > author, publisher, date, content, etc.


    Yeah, I exhausted Google. I originally had only a hardcopy which I
    think was a handout at some Digital (possibly Compaq) bash.

    -Neil



  4. Re: Volume Shadowing Availability

    Found something with very similar material here (http://www.vldb.org/
    conf/1988/P331.PDF) if anyone else is interested.

    -Neil



  5. Re: Volume Shadowing Availability

    Neil Lowden wrote:
    >>Have you tried Google? Plug in what you remember about the title,
    >>author, publisher, date, content, etc.

    >
    >
    > Yeah, I exhausted Google. I originally had only a hardcopy which I
    > think was a handout at some Digital (possibly Compaq) bash.
    >
    > -Neil
    >
    >


    The only thing I have ever encountered that goes into any detail about
    RAID is a document called "The RAID Book". It was, at one time,
    available from Digital. I got my copy when a former boss dropped his
    copy in the trash! I've found it quite handy and that former boss saved
    me $29.95!


  6. Re: Volume Shadowing Availability

    On Aug 24, 8:34 am, Neil Lowden wrote:
    > Hi Guys
    >
    > There was a document kicking around some 10 years ago that gave a
    > mathematical analysis of relative availability with single, two and
    > three member shadow sets. Guess it was about 15-20 pages long.
    >
    > Anyone have an electronic copy or know where it was published?


    I don't have an electronic copy handy but I believe it was in a
    presentation by Ken Bates. I've heard that Ken has since retired
    (damn!) and I don't know who has access to his old papers. My best
    guess would be to search the Decus presentation archives (if they
    exist) for Ken's papers - beware, however, that there were a *LOT* of
    them since he was at just about every darn conference anywhere in the
    world (or at least it seemed like it).

    If I remember right, a 3 member shadow set should be good for about
    200 years.

    .../Ed


  7. Re: Volume Shadowing Availability

    Ed Wilts wrote:
    > On Aug 24, 8:34 am, Neil Lowden wrote:
    >
    >>Hi Guys
    >>
    >>There was a document kicking around some 10 years ago that gave a
    >>mathematical analysis of relative availability with single, two and
    >>three member shadow sets. Guess it was about 15-20 pages long.
    >>
    >>Anyone have an electronic copy or know where it was published?

    >
    >
    > I don't have an electronic copy handy but I believe it was in a
    > presentation by Ken Bates. I've heard that Ken has since retired
    > (damn!) and I don't know who has access to his old papers. My best
    > guess would be to search the Decus presentation archives (if they
    > exist) for Ken's papers - beware, however, that there were a *LOT* of
    > them since he was at just about every darn conference anywhere in the
    > world (or at least it seemed like it).
    >
    > If I remember right, a 3 member shadow set should be good for about
    > 200 years.
    >


    Only if someone keeps replacing the disks as they fail!




  8. Backup Media [was Re: Volume Shadowing Availability]

    On Wed, 05 Sep 2007 12:35:43 -0700, Richard B. Gilbert
    wrote:

    > Ed Wilts wrote:
    >> On Aug 24, 8:34 am, Neil Lowden wrote:
    >>
    >>> Hi Guys
    >>>
    >>> There was a document kicking around some 10 years ago that gave a
    >>> mathematical analysis of relative availability with single, two and
    >>> three member shadow sets. Guess it was about 15-20 pages long.
    >>>
    >>> Anyone have an electronic copy or know where it was published?

    >> I don't have an electronic copy handy but I believe it was in a
    >> presentation by Ken Bates. I've heard that Ken has since retired
    >> (damn!) and I don't know who has access to his old papers. My best
    >> guess would be to search the Decus presentation archives (if they
    >> exist) for Ken's papers - beware, however, that there were a *LOT* of
    >> them since he was at just about every darn conference anywhere in the
    >> world (or at least it seemed like it).
    >> If I remember right, a 3 member shadow set should be good for about
    >> 200 years.
    >>

    >
    > Only if someone keeps replacing the disks as they fail!
    >
    >

    Heard a discussion on the radio yesterday as I was driving, Photographer
    was
    being interviewed talking about films media nd the like and he said there
    were only 2 types of disc drives, those that have failed and those that are
    going to fail.

    Cleverly put, but it got me to thinking and googling today for various ways
    to backup discs. What is the future here? Is Blu-ray or HD DVD viable,
    how
    good is the media? Anyway just wondering what others are thinking about in
    this realm


    --
    PL/I for OpenVMS
    www.kednos.com

  9. Re: Backup Media [was Re: Volume Shadowing Availability]


    In article , "Tom Linden"
    writes:
    >On Wed, 05 Sep 2007 12:35:43 -0700, Richard B. Gilbert
    > wrote:
    >
    >> Ed Wilts wrote:
    >>> On Aug 24, 8:34 am, Neil Lowden wrote:
    >>>
    >>>> Hi Guys
    >>>>
    >>>> There was a document kicking around some 10 years ago that gave a
    >>>> mathematical analysis of relative availability with single, two and
    >>>> three member shadow sets. Guess it was about 15-20 pages long.
    >>>>
    >>>> Anyone have an electronic copy or know where it was published?
    >>> I don't have an electronic copy handy but I believe it was in a
    >>> presentation by Ken Bates. I've heard that Ken has since retired
    >>> (damn!) and I don't know who has access to his old papers. My best
    >>> guess would be to search the Decus presentation archives (if they
    >>> exist) for Ken's papers - beware, however, that there were a *LOT* of
    >>> them since he was at just about every darn conference anywhere in the
    >>> world (or at least it seemed like it).
    >>> If I remember right, a 3 member shadow set should be good for about
    >>> 200 years.
    >>>

    >>
    >> Only if someone keeps replacing the disks as they fail!
    >>
    >>

    >Heard a discussion on the radio yesterday as I was driving, Photographer
    >>was

    >being interviewed talking about films media nd the like and he said there
    >were only 2 types of disc drives, those that have failed and those that
    >are
    >going to fail.
    >
    >Cleverly put, but it got me to thinking and googling today for various
    >ways
    >to backup discs. What is the future here? Is Blu-ray or HD DVD viable,
    >>how

    >good is the media? Anyway just wondering what others are thinking about
    >in
    >this realm
    >
    >
    >--
    >PL/I for OpenVMS
    >www.kednos.com
    >


    1. Shadowing doesn't help if data were deleted erroneously.
    2. At least Blu-Ray has an very complex error correction built in and
    does verify after write automatically.
    3. You can buy Blu-Ray recorders now (Never saw a HD DVD recorder
    on the German market till now!).
    4. You can buy DVDwrite to produce Blu-Ray discs under OpenVMS now.
    See www.dvdwrite.de
    Hope this helps
    Eberhard

  10. Re: Backup Media [was Re: Volume Shadowing Availability]

    Eberhard Heuser-Hofmann wrote:
    > 2. At least Blu-Ray has an very complex error correction built in and
    > does verify after write automatically.


    Both BlueRay and HD-DVD are awaiting market decision on which will
    survive. At this point in time, such media should be seen only as short
    term backup solution (aka, your daily/weekly backups) but should not be
    used for long term archival purposes, at least not until there is better
    visibility on what will happen to this market.

  11. Re: Backup Media [was Re: Volume Shadowing Availability]

    On 09/06/07 11:29, JF Mezei wrote:
    > Eberhard Heuser-Hofmann wrote:
    >> 2. At least Blu-Ray has an very complex error correction built in and
    >> does verify after write automatically.

    >
    > Both BlueRay and HD-DVD are awaiting market decision on which will
    > survive. At this point in time, such media should be seen only as short
    > term backup solution (aka, your daily/weekly backups) but should not be
    > used for long term archival purposes, at least not until there is better
    > visibility on what will happen to this market.


    Go to your local porn store and see which it stocks: Blu-Ray or
    HD-DVD. That's the one which will win.

    --
    Ron Johnson, Jr.
    Jefferson LA USA

    Give a man a fish, and he eats for a day.
    Hit him with a fish, and he goes away for good!

  12. Re: Backup Media [was Re: Volume Shadowing Availability]

    In article <8sXDi.39753$Pv4.13936@newsfe19.lga>,
    Ron Johnson wrote:

    > On 09/06/07 11:29, JF Mezei wrote:
    > > Eberhard Heuser-Hofmann wrote:
    > >> 2. At least Blu-Ray has an very complex error correction built in and
    > >> does verify after write automatically.

    > >
    > > Both BlueRay and HD-DVD are awaiting market decision on which will
    > > survive. At this point in time, such media should be seen only as short
    > > term backup solution (aka, your daily/weekly backups) but should not be
    > > used for long term archival purposes, at least not until there is better
    > > visibility on what will happen to this market.

    >
    > Go to your local porn store and see which it stocks: Blu-Ray or
    > HD-DVD. That's the one which will win.


    LOL! But many a true word spoken in jest. Dare I mention market
    penetration in this context?

    The is however another problem lurking, in terms of what Hollywood and
    the RIAA are allowed to get up to in this area.

    --
    Paul Sture

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

  13. Re: Backup Media [was Re: Volume Shadowing Availability]


    In article , JF Mezei
    writes:
    >Eberhard Heuser-Hofmann wrote:
    >> 2. At least Blu-Ray has an very complex error correction built in and
    >> does verify after write automatically.

    >
    >Both BlueRay and HD-DVD are awaiting market decision on which will
    >survive. At this point in time, such media should be seen only as short
    >term backup solution (aka, your daily/weekly backups) but should not be
    >used for long term archival purposes, at least not until there is better
    >visibility on what will happen to this market.
    >


    I want to contradict.

    For backup you'll find better solutions instead of using CD/DVD/Blu-Ray.
    It happens very often that you must migrate your backup files
    (800bpi Tape,1600bpi,DAT,TK50,TK70,DLT III,DLT IV etc.).

    I can read my CDs burnt at least five years ago. The same is true for
    DVDs.

    The industry produces optical drives that can read all formats and media
    and one drive that is capable to read old media is
    sufficient if you need to migrate to another solution. Why do you
    hesitate in case of using optical drives and trust tapes that have a
    much higher rate of change.

    Eberhard

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  14. Re: Backup Media [was Re: Volume Shadowing Availability]

    On Sep 7, 5:19 am, vax...@chclu.chemie.uni-konstanz.de (Eberhard
    Heuser-Hofmann) wrote:
    > In article , JF Mezei
    >
    > writes:
    > >Eberhard Heuser-Hofmann wrote:
    > >> 2. At least Blu-Ray has an very complex error correction built in and
    > >> does verify after write automatically.

    >
    > >Both BlueRay and HD-DVD are awaiting market decision on which will
    > >survive. At this point in time, such media should be seen only as short
    > >term backup solution (aka, your daily/weekly backups) but should not be
    > >used for long term archival purposes, at least not until there is better
    > >visibility on what will happen to this market.

    >
    > I want to contradict.
    >
    > For backup you'll find better solutions instead of using CD/DVD/Blu-Ray.
    > It happens very often that you must migrate your backup files
    > (800bpi Tape,1600bpi,DAT,TK50,TK70,DLT III,DLT IV etc.).
    >
    > I can read my CDs burnt at least five years ago. The same is true for
    > DVDs.
    >
    > The industry produces optical drives that can read all formats and media
    > and one drive that is capable to read old media is
    > sufficient if you need to migrate to another solution. Why do you
    > hesitate in case of using optical drives and trust tapes that have a
    > much higher rate of change.
    >
    > Eberhard


    [...]

    But they're so small: 700 MB and 7 GB (?) each.

    To archive my trading data I need dozens and dozens of CD's. And I
    have to prepare them on a logical-disk container file. The same data
    can fit on only a few DLT IV tapes without the need for container-file
    logical disks.

    Maybe they could make 12" optical disks? That would help, but still be
    outdone capacity-wise by tapes.

    AEF


  15. Re: Backup Media [was Re: Volume Shadowing Availability]


    In article <1189168029.533405.271620@k79g2000hse.googlegroups. com>, AEF
    writes:
    >On Sep 7, 5:19 am, vax...@chclu.chemie.uni-konstanz.de (Eberhard
    >Heuser-Hofmann) wrote:
    >> In article , JF Mezei
    >>
    >> writes:
    >> >Eberhard Heuser-Hofmann wrote:
    >> >> 2. At least Blu-Ray has an very complex error correction built in

    >and
    >> >> does verify after write automatically.

    >>
    >> >Both BlueRay and HD-DVD are awaiting market decision on which will
    >> >survive. At this point in time, such media should be seen only as

    >short
    >> >term backup solution (aka, your daily/weekly backups) but should not

    >be
    >> >used for long term archival purposes, at least not until there is

    >better
    >> >visibility on what will happen to this market.

    >>
    >> I want to contradict.
    >>
    >> For backup you'll find better solutions instead of using

    >CD/DVD/Blu-Ray.
    >> It happens very often that you must migrate your backup files
    >> (800bpi Tape,1600bpi,DAT,TK50,TK70,DLT III,DLT IV etc.).
    >>
    >> I can read my CDs burnt at least five years ago. The same is true for
    >> DVDs.
    >>
    >> The industry produces optical drives that can read all formats and

    >media
    >> and one drive that is capable to read old media is
    >> sufficient if you need to migrate to another solution. Why do you
    >> hesitate in case of using optical drives and trust tapes that have a
    >> much higher rate of change.
    >>
    >> Eberhard

    >
    >[...]
    >
    >But they're so small: 700 MB and 7 GB (?) each.
    >
    >To archive my trading data I need dozens and dozens of CD's. And I
    >have to prepare them on a logical-disk container file. The same data
    >can fit on only a few DLT IV tapes without the need for container-file
    >logical disks.
    >
    >Maybe they could make 12" optical disks? That would help, but still be
    >outdone capacity-wise by tapes.
    >
    >AEF
    >
    >


    Your are right! That's why I see the need for many people to switch
    to Blu-Ray: 45 GB BD-R DL or rewritable BD-RE DL.

    And you can get it now!

    Eberhard

  16. Re: Backup Media [was Re: Volume Shadowing Availability]

    AEF wrote:
    > On Sep 7, 5:19 am, vax...@chclu.chemie.uni-konstanz.de (Eberhard
    > Heuser-Hofmann) wrote:
    >
    >>In article , JF Mezei
    >>
    >> writes:
    >>
    >>>Eberhard Heuser-Hofmann wrote:
    >>>
    >>>>2. At least Blu-Ray has an very complex error correction built in and
    >>>> does verify after write automatically.
    >>>
    >>>Both BlueRay and HD-DVD are awaiting market decision on which will
    >>>survive. At this point in time, such media should be seen only as short
    >>>term backup solution (aka, your daily/weekly backups) but should not be
    >>>used for long term archival purposes, at least not until there is better
    >>>visibility on what will happen to this market.

    >>
    >>I want to contradict.
    >>
    >>For backup you'll find better solutions instead of using CD/DVD/Blu-Ray.
    >>It happens very often that you must migrate your backup files
    >>(800bpi Tape,1600bpi,DAT,TK50,TK70,DLT III,DLT IV etc.).
    >>
    >>I can read my CDs burnt at least five years ago. The same is true for
    >>DVDs.
    >>
    >>The industry produces optical drives that can read all formats and media
    >>and one drive that is capable to read old media is
    >>sufficient if you need to migrate to another solution. Why do you
    >>hesitate in case of using optical drives and trust tapes that have a
    >>much higher rate of change.
    >>
    >>Eberhard

    >
    >
    > [...]
    >
    > But they're so small: 700 MB and 7 GB (?) each.
    >
    > To archive my trading data I need dozens and dozens of CD's. And I
    > have to prepare them on a logical-disk container file. The same data
    > can fit on only a few DLT IV tapes without the need for container-file
    > logical disks.
    >
    > Maybe they could make 12" optical disks? That would help, but still be
    > outdone capacity-wise by tapes.
    >
    > AEF
    >


    At one time they DID make 12" optical disks. Google for "WORM" or
    "Write Once Read Mostly". It has been 12-15 years since I've seen one.



  17. Re: Backup Media [was Re: Volume Shadowing Availability]

    On Sep 7, 8:38 am, vax...@chclu.chemie.uni-konstanz.de (Eberhard
    Heuser-Hofmann) wrote:
    > In article <1189168029.533405.271...@k79g2000hse.googlegroups. com>, AEF
    >
    >
    >
    > writes:
    > >On Sep 7, 5:19 am, vax...@chclu.chemie.uni-konstanz.de (Eberhard
    > >Heuser-Hofmann) wrote:
    > >> In article , JF Mezei

    >
    > >> writes:
    > >> >Eberhard Heuser-Hofmann wrote:
    > >> >> 2. At least Blu-Ray has an very complex error correction built in

    > >and
    > >> >> does verify after write automatically.

    >
    > >> >Both BlueRay and HD-DVD are awaiting market decision on which will
    > >> >survive. At this point in time, such media should be seen only as

    > >short
    > >> >term backup solution (aka, your daily/weekly backups) but should not

    > >be
    > >> >used for long term archival purposes, at least not until there is

    > >better
    > >> >visibility on what will happen to this market.

    >
    > >> I want to contradict.

    >
    > >> For backup you'll find better solutions instead of using

    > >CD/DVD/Blu-Ray.
    > >> It happens very often that you must migrate your backup files
    > >> (800bpi Tape,1600bpi,DAT,TK50,TK70,DLT III,DLT IV etc.).

    >
    > >> I can read my CDs burnt at least five years ago. The same is true for
    > >> DVDs.

    >
    > >> The industry produces optical drives that can read all formats and

    > >media
    > >> and one drive that is capable to read old media is
    > >> sufficient if you need to migrate to another solution. Why do you
    > >> hesitate in case of using optical drives and trust tapes that have a
    > >> much higher rate of change.

    >
    > >> Eberhard

    >
    > >[...]

    >
    > >But they're so small: 700 MB and 7 GB (?) each.

    >
    > >To archive my trading data I need dozens and dozens of CD's. And I
    > >have to prepare them on a logical-disk container file. The same data
    > >can fit on only a few DLT IV tapes without the need for container-file
    > >logical disks.

    >
    > >Maybe they could make 12" optical disks? That would help, but still be
    > >outdone capacity-wise by tapes.

    >
    > >AEF

    >
    > Your are right! That's why I see the need for many people to switch
    > to Blu-Ray: 45 GB BD-R DL or rewritable BD-RE DL.
    >
    > And you can get it now!
    >
    > Eberhard


    OK, 45 GB is MUCH better. Cool!

    AEF


  18. Re: Backup Media [was Re: Volume Shadowing Availability]

    On Sep 7, 8:49 am, "Richard B. Gilbert"
    wrote:
    > AEF wrote:
    > > On Sep 7, 5:19 am, vax...@chclu.chemie.uni-konstanz.de (Eberhard
    > > Heuser-Hofmann) wrote:

    >
    > >>In article , JF Mezei

    >
    > >> writes:

    >
    > >>>Eberhard Heuser-Hofmann wrote:

    >
    > >>>>2. At least Blu-Ray has an very complex error correction built in and
    > >>>> does verify after write automatically.

    >
    > >>>Both BlueRay and HD-DVD are awaiting market decision on which will
    > >>>survive. At this point in time, such media should be seen only as short
    > >>>term backup solution (aka, your daily/weekly backups) but should not be
    > >>>used for long term archival purposes, at least not until there is better
    > >>>visibility on what will happen to this market.

    >
    > >>I want to contradict.

    >
    > >>For backup you'll find better solutions instead of using CD/DVD/Blu-Ray.
    > >>It happens very often that you must migrate your backup files
    > >>(800bpi Tape,1600bpi,DAT,TK50,TK70,DLT III,DLT IV etc.).

    >
    > >>I can read my CDs burnt at least five years ago. The same is true for
    > >>DVDs.

    >
    > >>The industry produces optical drives that can read all formats and media
    > >>and one drive that is capable to read old media is
    > >>sufficient if you need to migrate to another solution. Why do you
    > >>hesitate in case of using optical drives and trust tapes that have a
    > >>much higher rate of change.

    >
    > >>Eberhard

    >
    > > [...]

    >
    > > But they're so small: 700 MB and 7 GB (?) each.

    >
    > > To archive my trading data I need dozens and dozens of CD's. And I
    > > have to prepare them on a logical-disk container file. The same data
    > > can fit on only a few DLT IV tapes without the need for container-file
    > > logical disks.

    >
    > > Maybe they could make 12" optical disks? That would help, but still be
    > > outdone capacity-wise by tapes.

    >
    > > AEF

    >
    > At one time they DID make 12" optical disks. Google for "WORM" or
    > "Write Once Read Mostly". It has been 12-15 years since I've seen one.


    Yes, I remember them. The one I saw had excellent picture quality, at
    least for back then (circa mid-80s). They were called Laserdiscs, I
    believe, at least the video ones. Oh, of course: Laserdisc (and
    videodisc?) for video, WORM for computer data. Sounds right?

    OK, I'll look on the net.

    AEF


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