Hi Cheers for the guidance. Thanks
On Fri, 2005-09-09 at 09:37 -0400, Jon LaBadie wrote: > On Fri, Sep 09, 2005 at 09:39:31AM +0100, Chuck Amadi Systems Administrator > wrote: > > Hi I have managed to config the hard disk partitions in my disklist but > > I am short of tape space to include the remainder of the hard disk > > partitions. > > > > I had initially run the following commands is it possible to get > > compression functioning to enable to use 40GB as opposed to native 20GB. > > > > * - amtapetype -f /dev/nst0 # determine tape type takes along time > > * - turn off datacompression run mt command that controls magnetic tape > > drive operation. * - mt -f /dev/nst0 status and mt -f /dev/nst0 > > datcompression 0 Compression off. > > > > As I don't want to buy bigger tapes if possible. > > Your tape's capacity is 20GB! Not 40GB, never will be, no way, no how. > > But compression (hardware or software) might be able to shrink a lot of > data down to 20GB. > > The rub is that compression algorithms, whether applied by your computer > or by the computer in your tape drive, are only effective the first time > they are applied. And as PB pointed out, when fed already compressed > data, the dumb algorithm used by the tape drive is likely to expand, > rather than shrink, the data! > > An analogy, your new 250GB hard disk drive. If you use it to store a > bunch of zip'ed files, does it become a 500GB hard disk drive? No, > it is still a 250GB drive that happens to be storing compressed data. > > Similarly, your 20GB tape stores 20GB of data. Those data may be > 20GB of plain old uncompressed information, or a lot more information > that is compressed by your computer before taping or by the drive > during taping -- but not both!. > -- Unix/ Linux Systems Administrator Chuck Amadi The Surgical Material Testing Laboratory (SMTL), Princess of Wales Hospital Coity Road Bridgend, United Kingdom, CF31 1RQ. Email chuck.smtl.co.uk Tel: +44 1656 752820 Fax: +44 1656 752830
