Sybase ASE Backup Server ‘compress::X::’ vs ‘with compression = X’ syntax
ASE, Backup Server, Databases, Sybase Add commentsStarting in ASE 12.5.2, Sybase added the with compression = X syntax, prior releases required the compress::X:: syntax. What is the difference?
In releases prior to 12.5.4 and 15.0.2, the two were functionally the same. Since 12.5.4 and 15.0.2, they are different:
ASE tells the backup server to load the zlib library and dump the database model to the file /tmp/model.dmp through the compress filter. The entire data stream is compressed. If you look at the dump file in a hex editor, then you will see the entire file is compressed.
ASE tells the backup server to load the zlib library and dump database model to the file /tmp/model.dmp but only the data volume is actually compressed. If you look at the dump file in a hex editor, you will see the first two volumes are mostly empty data (binary 0’s) but the embedded third volume is compressed.
You need to understand that whenever you dump a database to a file using this syntax, there are three volumes that are dumped. Two are administrative and the third is the data of your database.
In ASE 12.5.4 and 15.0.2, the Archive Database functionality was added
ASE requires that the archive file, your database dump file, is dumped with the “with compression = X” format, if it is compressed, as it needs access to the administrative volumes.
So, how does this affect us as DBAs? If you dump a database with ‘with compression = X’ on 12.5.4 esd5, you will NOT be able to load it into 12.5.3 esd 5 without using the 12.5.4 backup server. This has bitten us in the past when we attempted to load the customers’ database dumps.
Don’t forget to look at Sybase’s manual from time to time ;-).
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