On Thursday 23 October 2014 16:48:50 Jon LaBadie did opine And Gene did reply: > On Thu, Oct 23, 2014 at 10:34:38AM -0400, Gene Heskett wrote: > > On Thursday 23 October 2014 01:28:01 Tom Robinson did opine > > ... > > > If you are feeding the tape device compressed files, and the drives > > compressor is enabled too, this will quite often cause file > > expansions on the tape itself. The drives compressor, because it is > > intended to handle the compression on the fly, is generally not > > sophisticated enough to do any further compression and will add to > > the datasize, expanding what actually goes down the cable to the > > drives heads. > > Tom is using an LTO drive (-5 I think). Most modern tape > drives, including all LTO's do not exhibit the bad behavior > of the DDS drives with their run-length encoding scheme. > > IIRC, they have enough cpu smarts and memory to first > collect the data in memory, try to compress it to another > another memory buffer, and if it is enlarged the block > is saved "uncompressed". > > Note, instead of a flag at the start of the tape indicating > compressed or uncompressed, there is a flag for each tape > block. > > jl
Interesting Jon. Finally some smarter drives. I'll try to keep that in mind. Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) Genes Web page <http://geneslinuxbox.net:6309/gene> US V Castleman, SCOTUS, Mar 2014 is grounds for Impeaching SCOTUS
