Re: Compress datafiles for backup

Sameer Utrankar (utrankas_at_coned.com) wrote:
} sds_at_dataplusnet.com (Strategic Data Systems) wrote:
} >If your tape drive is already doing hardware compression,
} >you would not benefit from compressing the files via
} >software.
} >Scott Overby
} >sds_at_dataplusnet.com
} What do you mean ? With or without hardware compression, doesn't tape
} drive has "a capacity" ? For example, when I use 120m DDS-2 Data
} Cartridge on HP-Ux - which mentions the capacity as 4 GB - do you mean
} to say it should be able to hold much more than 4GB of oracle
} datafiles because of hardware compression ? If yes, I don't have a
} problem. If no, then compressing 12 GB of oracle datafiles to get 4GB
} of compressed output and then putting that to tape will help. Right ?

Many DDS-2 drives give optimistic 16GB capacities based on hardware compression. If you use software compression before you send the data to the drive, it will not be able to compress it any further and from what some people have said, it could actually add some overhead in trying to compress the already compressed data.

Tom

--

Thomas M. Buccelli (tmb_at_idm.com)

#include <std_disclaimer.h>