Hi,

Re:
> After a system-crash we discovered that the content of one file was
> lost. This probably happened, because the information was still in the
> memory, while the machine went down.
>
> I'm looking now for a possibility to prevent this to happen again. The
> idea is, to force the write-command to write directly to the harddrive.
> A got several tips from colleagues, one was the FCONTROL statement and
> another a so-called transaction manager. Does anybody have informations
> or experience with these features? Or does anybody have another idea?

First, "START RECOVERY" vs. "START NORECOVERY" has absolutely
nothing to do with this.

There are two basic techniques to avoid data loss for a single file:

   1) manually post the data to disk periodically (generally by calling
      FCONTROL <file#>, 2)

      Drawback: can cause extremely bad performance problems.  The
     problem gets worse with the size of the file and the size of memory.

    Advantage: you decide precisely when to post the data to disk.

or

   2) attach the file to the transaction manager (via FSETMODE <file>, 1)

      Drawback: can cause some performance problems.  File cannot be
     easily detached from the transaction manager.  Also, you don't know
     for sure when the data gets to disk ... although it's generally within the
     next minute or so, max.    Also, excessive XM (transaction manager)
     activity can cause other system problems.

     Advantage: you attach it once and don't have to change any code.

SS




Stan Sieler                                           [log in to unmask]
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