Re: Optimal tape block size?/DDS3 Anyone?

Posted in 1997

Topics: Performance & Tuning, Installation, Setup & Upgrades

Frederic MARAND — Mon, 01 Sep 1997 21:45:35 GMT — source: Informix-list mailing list archive (1991-1998)

aslater@jocko.bri.hp.com (Al Slater) wrote: >John (john@wallstreet.demon.co.uk) wrote: >: Acquired 2xDDS3 drives - No clues in the HP manuals on optimum blocksize - >: anyone?! >: Cosmo Lee <*NO-SPAM*cosmo@echonyc.com> wrote in article >: <33FF4DB0.9ECE899D@echonyc.com>... >: > Platform: >: > Unixware 2.1, Informix Online 7.22, Compaq Proliant 1500, Archive Python >: > 28388 tape drive. >32k will do fine. Last I looked the UNIX Install Guide that comes >with the SureStore DATs _does_ mention this someplace (okay so it maybe >isn't in neon five mile high lettering, but it is in there someplace ;-). >cheers, >al. >(not speaking for HP..) Actually, optimal block size usually depends on the machine you're working with : using too small a block size generally gives poor performance, but too large a block size can give a drive the "hiccups" between accesses. If you're regularly using this particular drive on this particular server, I suggest you plot backup time against buffer size, as this is the only safe way to determine optimal block size. Frederic G. MARAND Agorus SA / OSI SARL http://www.chez.com/osi 9500+ micro prices online