Date: Sun, 18 Feb 1996 20:47:19 -0600 (CST) From: Bob Willcox <bob@luke.pmr.com> To: se@zpr.uni-koeln.de (Stefan Esser) Cc: freebsd-current@freefall.freebsd.org Subject: Re: Exabyte 8mm tape drive performance in -current? Message-ID: <199602190247.UAA02537@luke.pmr.com> In-Reply-To: <199602182259.AA05589@Sysiphos> from "Stefan Esser" at Feb 18, 96 11:59:52 pm
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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
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