From owner-freebsd-current Sun Feb 18 18:47:43 1996 Return-Path: owner-current Received: (from root@localhost) by freefall.freebsd.org (8.7.3/8.7.3) id SAA21639 for current-outgoing; Sun, 18 Feb 1996 18:47:43 -0800 (PST) Received: from luke.pmr.com (luke.pmr.com [206.224.65.132]) by freefall.freebsd.org (8.7.3/8.7.3) with SMTP id SAA21633 for ; Sun, 18 Feb 1996 18:47:38 -0800 (PST) Received: (from bob@localhost) by luke.pmr.com (8.6.12/8.6.9) id UAA02537; Sun, 18 Feb 1996 20:47:19 -0600 From: Bob Willcox Message-Id: <199602190247.UAA02537@luke.pmr.com> Subject: Re: Exabyte 8mm tape drive performance in -current? To: se@zpr.uni-koeln.de (Stefan Esser) Date: Sun, 18 Feb 1996 20:47:19 -0600 (CST) Cc: freebsd-current@freefall.freebsd.org In-Reply-To: <199602182259.AA05589@Sysiphos> from "Stefan Esser" at Feb 18, 96 11:59:52 pm X-Mailer: ELM [version 2.4 PL24] Content-Type: text Sender: owner-current@FreeBSD.ORG Precedence: bulk Stefan Esser wrote: > > On Feb 18, 15:55, Bob Willcox wrote: > } Subject: Exabyte 8mm tape drive performance in -current? > } I have observed that the (read and write) performance of my 8mm > } Exabyte tape drives on my -current system runs roughly half of what > } it is on my 2.1-stable systems (100kb/sec vs. 200kb/sec). This is > } with both the NCR 810 and Adaptec 2940 adapters and using programs > } such as dump, tar, dd, team. The systems that I have compared have > } roughly the same hardware (both are 100MHz Pentiums). Performance > } on my Wangtek QIC-525 tape drive is about the same. Can anybody > } offer up an explaination of why this is and what might be done to > } fix it? > > Did you compare the output of "mt status" ? > The EXABYTE drives are known to become very > slow if used with an unsuitable blocksize. > Make sure you don't use 512 byte fixed size > blocks with -current ... On the -current system I cannot change the blocksize away from 512. Normally I use variable blocksize and use mt to set it to 0. This does not work on -current (for either the NCR or Adaptec adapters). Most likely this is my problem. I hadn't bothered to check the blocksize before since the script I was running was setting it to 0 (it was trying to anyway). -- Bob Willcox bob@luke.pmr.com (or obiwan%bob@uunet.uu.net) Austin, TX