On Thursday 19 June 2003 14:09, Ean Kingston wrote: >> -----Original Message----- >> >> On Thursday 19 June 2003 11:51, Ean Kingston wrote: >> >I couldn't find this one in the list archives, so here it is. >> > >> >I'm using 40GB DLT tapes (according to the label). Despite what >> > the comment produced says, I used the non-compressed device. I >> > didn't give it an estimate for the tapesize. >> > >> >Writing 256 Mbyte compresseable data: 34 sec >> >Writing 256 Mbyte uncompresseable data: 105 sec >> >WARNING: Tape drive has hardware compression enabled >> >Estimated time to write 2 * 1024 Mbyte: 840 sec = 0 h 14 min >> >wrote 1102644 32Kb blocks in 3372 files in 21817 seconds (short >> > write) wrote 1101228 32Kb blocks in 6756 files in 29828 seconds >> > (short write) define tapetype HP-DLT1e { >> > comment "just produced by tapetype prog (hardware compression >> > on)" length 34499 mbytes >> > filemark 13 kbytes >> > speed 1399 kps >> >} >> >> And it appears the hardware compressor being on cost you 5.5 gigs. >> The various 'tapetype' programs all use the output of /dev/urandom >> as the data source, and the output of /dev/urandom is not >> compressible, and will in fact grow by about the percentage you >> see above in being passed thru the hardware compressor. >> >> As others have noted Ean, you can turn it off, but this must be >> done for every new tape that's inserted as the recognition phase >> of the drive will turn it back on when the tapes are changed. >> Such info as how to turn it on/off should be on the drive makers >> web page. To your vendor its obviously not a very high priority >> to obtain that info for you else he would have fired up a browser >> and found it on the spot. > >I'm using Solaris and, according to the documentation, it should not > be using hardware compression unless I specify the 'compress' > device (/dev/rmt/0cn) as opposed to the one I did use > (/dev/rmt/0n). If what you say it true there is some way to force > HW compression for the tape drive regardless of what the OS wants.
I'll leave that pronouncement to the Sol experts here, like Jon LaBadie. -- Cheers, Gene AMD [EMAIL PROTECTED] 320M [EMAIL PROTECTED] 512M 99.26% setiathome rank, not too shabby for a WV hillbilly Yahoo.com attornies please note, additions to this message by Gene Heskett are: Copyright 2003 by Maurice Eugene Heskett, all rights reserved.