From owner-freebsd-current Sat Feb 20 4:15:22 1999 Delivered-To: freebsd-current@freebsd.org Received: from alushta.NL.net (alushta.NL.net [193.78.240.22]) by hub.freebsd.org (Postfix) with ESMTP id CA28910E05 for ; Sat, 20 Feb 1999 04:15:18 -0800 (PST) (envelope-from paulz@trantor.xs4all.nl) Received: from stuyts by alushta.NL.net with UUCP id <5133-9146>; Sat, 20 Feb 1999 13:15:05 +0100 Received: from trantor.xs4all.nl (uucp@localhost) by terminus.stuyts.nl (8.9.3/8.9.2) with UUCP id NAA02438; Sat, 20 Feb 1999 13:03:02 +0100 (MET) (envelope-from paulz@trantor.xs4all.nl) Received: from trantor.xs4all.nl (localhost [127.0.0.1]) by trantor.xs4all.nl (8.9.3/8.8.5) with ESMTP id MAA01220; Sat, 20 Feb 1999 12:59:06 +0100 (MET) Message-Id: <199902201159.MAA01220@trantor.xs4all.nl> X-Mailer: exmh version 2.0.2 2/24/98 To: "Kenneth D. Merry" Cc: freebsd-current@FreeBSD.ORG Subject: Re: Slow seq. write on Seagate ST36530N In-reply-to: Your message of "Fri, 19 Feb 1999 14:15:52 MST." <199902192115.OAA04024@panzer.plutotech.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Date: Sat, 20 Feb 1999 12:59:05 +0100 From: Paul van der Zwan Sender: owner-freebsd-current@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG > Paul van der Zwan wrote... > > > > I am having some performance problems on my -current ( update last weekend) > > I hooked up a new Seagate ST36530N yesterday ( connected to an Adaptec 2940U) > Andreas Klemm has had similar trouble, as he pointed out. > Can you check and see whether or not you have write caching turned on for > your disk? I have seen problems with sequential writes that appear to be > caused by conflicts between FreeBSD's caching policy and disk caching > policies. These problems often go away when you disable write caching on a > disk. > > The Write Cache Enable (WCE) bit is in mode page 8. To check it: > > camcontrol modepage -n da -u 1 -v -m 8 > > To edit the mode page: > > camcontrol modepage -n da -u 1 -v -m 8 -e > > Let me know whether that affects the problem at all. This did not improve anything , but I think I have found the couse. In that modepage there is a DISC value which was 0 on the IBM and 1 on the Seagate. I remembered a ' Enable disconnect' option in the Adaptec 2940 bios, setting this to 'off' for both harddisks led to a huge performance increase on the Seagate. If I also enable Ultra mode iozone write goes from 1.5 MB/s to 12 MB/s ( a factor of 8 !!!). Paul -- Paul van der Zwan paulz @ trantor.xs4all.nl "I think I'll move to theory, everything works in theory..." To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message