My experience is with AIX using the ADSM api for informix
The backup is treated as a single continuation. ADSM requests a new tape as
the previous one becomes full.
We struggled with server performance for quite some time  backing up to disk
as our disk pool is only 25G, backups are 19+G
and migration of that client's data would commence during the backup. We
have not figured out how/why the ADSM informix API backups will not
 wait for a tape mount nor will it try to write to the disk pool if it's
estimated backup size exceeds the available disk pool space.
We now go directly to tape.  Maybe not quite as efficient as writing to
disk, but backups now wait for a tape mount.
MV



        -----Original Message-----
        From:   Jason Howard [SMTP:jason.howard AT MINDSPRING DOT COM]
        Sent:   Wednesday, October 06, 1999 4:33 PM
        To:     ADSM-L AT VM.MARIST DOT EDU
        Subject:        ADSM - Informix DB Migration ?

        Is this scenario possible?
        Here is my setup---

        ADSM for NT 3.1.2.41 w/ 700 GB of Data Volume
        ADIC Scalar 1000 Library w/ 4 AIT Drives Fibre Channel attached
        Client - Solaris 2.6 running Informix 7.3
        SQL Backtrack for Informix 2.1.00

        I have a 500 GB DB in INFORMIX that eventually will grow to 1 TB.

        I want to perform a full backup of the DB, what is going to happen
when
        I do a migration to tape.
        Does ADSM treat the DB as one file or multiple files.  In other
words,
        will it stripe the data simultaneously across multiple tape drives
or
        will it use 1 drive and 1 tape until the tape is full and move on to
the
        next tape.  If I calculate that correctly, then if I back up a 500GB
        file it will take 23 hours if I get 6 MB/s on my tape drives.

        If ADSM will only use 1 drive, how can I migrate this DB within a
        reasonable amount of time.
        Take this as theory only.  Please do not jump on the AIX vs NT  ADSM
        wagon. I know the dispute. Please answer theoretically only.

        Thanks!!!!!


        --
        Jason Howard
        Systems Consultant
        Blue Cross and Blue Shield of Alabama
        jhoward AT bcbsal DOT org
        205-444-6203