ddm_save.pl does not zip the save file enough (poor/low compression on DDMdb backup file)

Products

• CA Spectrum
• DX NetOps

Issue/Introduction

We recently upgraded the Spectrum from 10.3.1 to 10.4.2 and we noticed a poor/low compression on the DDMdb backup file.

As per the documentation we have update the post_olb_script for ddmdb backups:

./ddm_save.pl -f $backup_dir/db_$time_string.DDMDb > $backup_dir/ddm_backup.log 2>&1

The size of the DDMDB backup file (.mbi) has increased almost 4 times as compared to old backups in 10.3.1 (from 420 MB to 2 GB) using the above script, is this normal?

Environment

Release : 10.4.1

Component : Spectrum Core / SpectroSERVER

Cause

The default mysql compression method does not compress enough

Resolution

There is an increase in size due to the change in mysql from myisam to innodb. Innodb is more of a transactional db and the event tables are broken up into days. This is normal as noted here:

https://knowledge.broadcom.com/external/article?articleId=122472

However, the savefile is rather large with the default compression.  To enable better compression, edit the $SPECROOT/SS/DDM/ddm_save.pl and change this entry:

Locate this section in the ddm_save.pl file:

$cmd = "$MYSQLBACKUP --defaults-file=$MYSQL_CONF --compress --user=$USERNAME --password=$PASSWORD  --backup-dir=$backup_dir  --backup-image=$backup_image --include-tables=\"^ddmdb\.\" --use-tts  backup-to-image $REDIRECT_NULL_DEV";

And replace this parameter - To use --compress-method=lzma:

$cmd = "$MYSQLBACKUP --defaults-file=$MYSQL_CONF --compress-method=lzma  --user=$USERNAME --password=$PASSWORD  --backup-dir=$backup_dir  --backup-image=$backup_image --include-tables=\"^ddmdb\.\" --use-tts  backup-to-image $REDIRECT_NULL_DEV";

 

This will be changed in a future release of Spectrum.

Additional Information

The lzma compression method also has compression levels that can be specified

The compression level is meaningful only with zlib and LZMA algorithms.
 --compress-level=LEVEL
              Specify value from 0-9.
              Specify value 0 to disable compression.
              Specify value 1 for fastest compression.
              Specify value 9 for best compression.


So --compress-method=lzma --compress-level=<LEVEL>  can be specified. The higher compression levels may require more time to compress and complete the backup.

 

 

Also review this KB article:

Failure in the mysqlbackup during the execution of post_olb_script does not generate event and alarm

https://knowledge.broadcom.com/external/article?articleId=206381