Re: Compression with ontape

David Williams wrote: > > In article <3517B655.CE63B0AD@cork.cig.mot.com>, Peter Wotherspoon > <wothersp@cork.cig.mot.com> writes > >Gabriela, > > > >Hi. > > > >I've always used compressed tape devices for Informix archiving, and I've not > >had any problems. If you have fewer metres of tape used up, I think you > >probably decrease the risk of getting a dropout on the tape, so you make the > >backup more secure, not less. It's also faster than not using compression. > > > >The only tricky thing is to accurately predict what level of compression you > >will achieve, so that you can set the tape parameters optimally. > > > >From my experience, DAT tapes are more reliable than EXABYTE, but if you > >replace the media regularly, everything should be OK. > > Informix didn't use to like supporting compressed devices. On > compressed tape drives the compression is usually implemented in > software (or microcode) on the tape drive. Some of the early compression > routines were buggy!! I thought the main problem, as Peter said, is predicting the actual usable tape size and hence the tape parameter value without running off the end of the tape. Cheers, -- Mark. +----------------------------------------------------------+-----------+ |Mark D. Stock - Informix SA http://www.informix.com |//////// /| |mailto:mdstock@informix.com FAQ http://www.iiug.org |///// / //| | +-----------------------------------+//// / ///| | Tel: +27 11 807 0313 |If it's slow, the users complain. |/// / ////| | Fax: +27 11 807 2594 |If it's fast, the users keep quiet.|// / /////| |Cell: +27 83 250 2325 |Therefore, "No news: travels fast"!|/ ////////| +----------------------+-----------------------------------+-----------+