SAP Note 24336 - NT: Hardware compression does not work

Symptom:

Although a tape unit with hardware compression is available and the compression is switched on as a default on the tape deck, it is inactive during database backups with BRBACKUP/BRARCHIVE. This means that the whole tape capacity (see Note 8707) cannot be used.
For example, on a 4mm DDS-2 disk drive with a 120m tape, you can store only 3800 MB instead of at least 8000 MB (uncompressed).
The cpio command started by the BRBACKUP/BRARCHIVE then runs on to the end of the tape: BR278E Command ... cpio ...
cpio: write error on file "...": The physical end of the tape has been
reached.
BR279E Return code from ... cpio ...
BR222E Copying ... failed.
Caution:
--------
You can use the command "mt -f /dev/mtx status" to determine whether hardware compression is really turned off. The mt.exe command is delivered with the SAP executables.

Cause and prerequisites

The default on the tape deck is reset after running NT Backup, regardless of whether hardware compression was chosen in this case or not.
This is a default function of NT Backup in Windows NT 3.5.

Solution

Option 1:
---------
Some tape decks have the option to define hardware compression not only as a default setting but as a fixed setting. Read the tape unit documentation and use this option if possible.

Option 2:
---------
Activate the hardware compression after running NT Backup:

• If the tape unit is connected as an external device, turn it off and then back on again, in order to reset the hardware compression mode to the default value.

• If the tape unit is integrated into the system unit, the NT system must be rebooted.

Option 3:
---------
You can activate the hardware compression manually using the program compression.exe which can be found on sapservx in the directory /general/misc/sapdba/[ntintel|ntalpha].

Option 4:
---------
In the meantime, a corrected version of NtBackup has become available. It does not change the compression status (on/off) of the tape station. It can be downloaded from sapserv3/sapserv4 from directory /dist/permanent/sapdba/[ntintel|ntalpha].
The executable there must be uncompressed before use.
ftp sapserv3/sapserv4
(User/Password): ftp/ftp
cd /dist/permanent/sapdba/[ntintel|ntalpha]
bin
get ntbackup.exe.Z
quit
uncompress ntbackup.exe.Z
Then replace the old file:
ren x:\winnt\system32\ntbackup.exe ntbackup\old
copy ntbackup.exe x:\winnt\system32\ntbackup.exe

Caution:
--------
The corrected version of NTBackup can be found in Service Pack 2 of NT 3.5 and NT 3.51.