From owner-freebsd-performance@FreeBSD.ORG Thu Jun 19 10:03:07 2003 Return-Path: Delivered-To: freebsd-performance@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 2114037B401; Thu, 19 Jun 2003 10:03:07 -0700 (PDT) Received: from adsl-63-198-35-122.dsl.snfc21.pacbell.net (adsl-63-198-35-122.dsl.snfc21.pacbell.net [63.198.35.122]) by mx1.FreeBSD.org (Postfix) with ESMTP id 3650043FCB; Thu, 19 Jun 2003 10:03:06 -0700 (PDT) (envelope-from j_guojun@lbl.gov) Received: from lbl.gov (localhost.pacbell.net [127.0.0.1]) ESMTP id h5JH6ihc000392; Thu, 19 Jun 2003 10:06:45 -0700 (PDT) (envelope-from j_guojun@lbl.gov) Sender: jin@adsl-63-198-35-122.dsl.snfc21.pacbell.net Message-ID: <3EF1EDA4.CBC4559@lbl.gov> Date: Thu, 19 Jun 2003 10:06:44 -0700 From: "Jin Guojun [NCS]" X-Mailer: Mozilla 4.76 [en] (X11; U; FreeBSD 4.8-RELEASE i386) X-Accept-Language: zh, zh-CN, en-US, en MIME-Version: 1.0 To: Petri Helenius References: <20030614190033.7F0DE37B407@hub.freebsd.org><20030615091254.M85497@bluhayz.org> <3EF0B507.2B1B6FDF@lbl.gov> <002101c335d9$f6664a20$812a40c1@PETEX31> <3EF0EABC.E9D75759@lbl.gov> <042501c33630$115159a0$812a40c1@PETEX31> Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8bit cc: freebsd-performance@freebsd.org cc: agent dero cc: Scott Long Subject: Re: freebsd-performance Digest, Vol 4, Issue 7 X-BeenThere: freebsd-performance@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Performance/tuning List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 19 Jun 2003 17:03:07 -0000 Petri Helenius wrote: > > But this seems to have different problem. At least write to RAID 1 requires > > twice bus bandwidth for soft RAID 1. So, read should be faster than write. > > But current read is 67 MB/s, write is 10 MB/s. Something is not working. > > Might be that whatever you´re using for the write waits for the second write > to complete before it issues a write on the first drive again. vinum does this, > it does not dispatch both writes at the same time. (I argued about this > being "broken" for a while but then gave up, I understand why doing > this differently does complicate the code, but at the same time improves > performance) The interesting thing is that the first write is fast every time I rebuilt file system (newfs). The write on soft RAID is about 3# MB/s. After a few large files on the file system, the write speed drops to 11-12 MB/s. Sooner or later, the write speed will stay at 9-10 MB/s. multiple writes will be lower around 8-9 MB/s (aggregated rate). The initial hardware RAID write rate is about 15 MB/s. This may be due to the battery backup write cache does no function correctly. The driver spits follwoing message at the same time: **Monitor** - Battery Fully Changed ... **Monitor** ERROR - Low Battery This may mean that cache is disbaled. -Jin