IDS Forum

Re: ISM Cannot Process DBSPACES that are 2GB or Greater in Size

Posted By: Peter J Diaz de Leon
Date: Monday, 4 October 2004, at 7:04 a.m.

In Response To: ISM Cannot Process DBSPACES that are 2GB or Greater in Size (Peter J Diaz de Leon )

Martin,

Thank you very much for clearing this up. :-)

-Peter J Diaz de Leon


Martin Fuerderer wrote:

>Hi,
>
>actually this is a misunderstanding on our part.
>
>ISM _can_ very well process dbspaces greater than 2 GB.
>Also there's nothing in ISM that would limit chunk size to
>2 GB (just to make that clear as well).
>
>ISM has an option to use the file system as backup media
>("ism_add -device <directory> -type file"). ISM will then create
>files in this directory to store the backup data. And due to a
>limit in ISM's file handling, these files cannot be bigger than
>2 GB. Therefore ISM creates multiple files when necessary
>and splits the data of backup objects bigger than 2 GB into
>these several files.
>This limit does not apply to tape drive media used with ISM,
>but only to "file system media".
>
>Since the backup data of dbspaces is sent to (and received from)
>ISM via some special portion in the IDS shared memory (and
>not the file system), there is no limitation to dbspace/chunk size.
>
>However, if you use ISM to backup file system files and these
>files would grow over 2 GB in size, then you have a problem.
>Usually backed up files are only some index files of ISM itself
>and maybe things like the ixbar file. I hope that none of these
>grows larger than 2 GB. (I guess you'd notice long before that
>there'd be a significant performance penalty when using ON-Bar
>and ISM.)
>
>[ BTW: a scrutinizing reader of release notes may notice, that
> the wrong note talks about DBSPACES being greater than
> 2 GB. But this is nothing new, as dbspaces consist of several
> chunks, where e.g. 5 chunks 2 GB each add up to 10 GB.
> And that was before the 2 GB chunk limit was removed. But
> backing up such a 10 GB dbspace never was a problem before
> and the ISM code (derived from Legato Networker) hasn't
> changed. So as I said before there is quite a misunderstanding.]
>
>This error in the release notes will be fixed (i.e. removed) with the
>next version.
>
>Regards,
>Martin
>--
>Martin Fuerderer
>IBM Informix Development Munich
>Data Management Solutions
>
>forum.subscriber@iiug.org wrote on 01.10.2004 21:10:46:
>
>
>>I am reviewing the doctumentation that came with IDS 9.40.UC5 and
>>something caught my eye.
>>
>>In the file "ids_ism_docnotes_9.40.txt" there is the following statement
>>
>>
>
>
>
>>in section 1.2.1
>>
>>"1.2.1 ISM Cannot Process DBSPACES that are 2GB or Greater in Size
>>
>>The Legato NetWorker 5.1 code used by ISM has a 2 GB size limitation."
>>
>>So whats the point of getting rid of the 2GB dbspace limitation and
>>still bundling
>>the Legato Networker code that doesn't support it.
>>
>>Come on IBM lets turn on our thinking caps.
>>
>>
>>



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Messages In This Thread

• ISM Cannot Process DBSPACES that are 2GB or Greater in Size
  Peter J Diaz de Leon -- Friday, 1 October 2004, at 3:10 p.m.
  • RE: ISM Cannot Process DBSPACES that are 2GB or Greater in Size
    Sebastian, Norma J. -- Friday, 1 October 2004, at 4:18 p.m.
  • Re: ISM Cannot Process DBSPACES that are 2GB or Greater in Size
    Mark D. Stock -- Saturday, 2 October 2004, at 12:43 p.m.
  • Re: ISM Cannot Process DBSPACES that are 2GB or Greater in Size
    Martin Fuerderer -- Monday, 4 October 2004, at 5:37 a.m.
  • Re: ISM Cannot Process DBSPACES that are 2GB or Greater in Size
    Peter J Diaz de Leon -- Monday, 4 October 2004, at 7:04 a.m.

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