| T.R | Title | User | Personal
Name | Date | Lines |
|---|
| 239.1 | You should see ADABAS code, German comments! | COOKIE::JANORDBY | | Thu Nov 03 1988 17:29 | 17 |
|
I am not as familiar with the VMS version of ADABAS as I should
be, but on the IBM side ADABAS can
1) Unload in its internal compressed format either directly to tape
or to disk.
2) Backup the database while it is being updated (3 or 4 years now)
3) can optionally unload in decompressed format into a sequential
file. (Part of the load of a sequential file involved data compression)
4) Loading a file involved building the relation for that file and
the associated indexes. Restoring a file is usually not done from
an unload, rather a backup which does not need to rebuild any part
of the database, it simply places an old copy where it used to go.
(if the origninal space is not available, anerror occurs)
5) I assume that the VMS version is at least along the same designs
as the IBM version, since it was actually a port to VMS.
Jamey
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| 239.2 | Same Physical Space ? | HGOVC::SIMONYTCHAN | I Come From Hong Kong | Fri Nov 04 1988 09:46 | 11 |
| 4) Loading a file involved building the relation for that file and
the associated indexes. Restoring a file is usually not done from
an unload, rather a backup which does not need to rebuild any part
of the database, it simply places an old copy where it used to go.
-> (if the origninal space is not available, anerror occurs)
Does it mean that the same physical space as that of the original
copy must be available in order to restore the backup?
Simon Chan
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| 239.3 | Differences | BROKE::BOOTH | What am I?...An Oracle? | Fri Nov 04 1988 17:20 | 17 |
| Adabas is written by two totally seperate development teams in Germany.
The IBM team writes in Assembler. The Digital team writes in Macro.
Consequently, the two products are never exactly in sync. There
are subtle differences in most areas, major ones elsewhere.
When I was in the field, the Adabas/VMS customers complained that
it was misery to restart the database after a system or database
problem. Hours were involved in bringing up the database again.
If online backup is available on the VAX, it is brand-new. If you
have other Adabas customers, talk to them about these questions.
Check out everything you can. The typical situation with Adabas/Natural
is that the user/developers love it, while the systems managers
hate it, because of the work they must do maintaining it.
---- Michael Booth
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| 239.4 | yup | COOKIE::JANORDBY | | Fri Nov 04 1988 18:11 | 11 |
| re: .2
In the IBM version, a backup will backup a physical copy of a file
or the entire database. If a file is to be restored, the physical
space that it previously occupied must be available. An unload is
a different mechanism (and slower). But an unload can be used as
input to a load that is independent of previous location.
Again, you must double check with customers to be sure this is the
same with the VMS version of ADABAS.
Jamey
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| 239.5 | Adabas (VMS) Backup details | WELMT2::DENT | | Fri Oct 27 1989 17:24 | 25 |
| Adabas (VMS) - all versions up to and including V1.5 use information
about the physical block numbers on disk to speed up access to data
with QIO. In addition chunks of the database are aligned on cylinder
boundaries on disk to speed up performance by reducing disk head
movement.
As Adabas uses physical disk blocks it is not possible to do a VMS
image backup and restore (Physical backup is ok) as the image backup
is almost certain to restore the data to different disk blocks.
The way to take a backup of the whole database or one or more files
in the database is with the Adabas utility ADABCK. This may be run
with the database active and may write data to 1 or 2 tapes or a
disk file. The disk file may then be copied to tape with VMS Backup.
As ADABCK takes advantage of knowing the physical layout of the
database and only backs up the parts of the database used it is
quicker than VMS Backup.
With the release of Adabas (VMS) V2 (approx end 89) the database
may be created as a "easy to use" or "high performance" database.
If "easy to use" then the restrictions on cylinder alignment and
contiguous files are removed and VMS image backup may be used.
Ian Dent
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| 239.6 | | TWOBOB::CLEARY | A deviant having fun..." | Sun Nov 05 1989 07:24 | 8 |
| If he only difference between `easy to use' and `high performance' is
the use of logical QIO's instead of physical QIO's, then I'd be very
surprised if the performance hit is noticable let alone measurable for
most applications. It's always been a source of amazement to me that
ADABAS did this. But then I've heard they write it all in assembler so
what else would you expect...
-mark
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