From mboxrd@z Thu Jan 1 00:00:00 1970 From: Spam Message-ID: <6557103468.20031117194401@tnonline.net> Subject: Re: [linux-lvm] Performance problem. In-Reply-To: <20031117193054.5dd7eec1.neuron@hollowtube.mine.nu> References: <3FB8F8A1.1060004@clin.ucl.ac.be> <1069087854.2408.0.camel@localhost.localdomain> <20031117181007.00e15a29.neuron@hollowtube.mine.nu> <3252989968.20031117183528@tnonline.net> <20031117191324.2047dbf3.neuron@hollowtube.mine.nu> <11955855390.20031117192313@tnonline.net> <20031117193054.5dd7eec1.neuron@hollowtube.mine.nu> MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-lvm-admin@sistina.com Errors-To: linux-lvm-admin@sistina.com Reply-To: linux-lvm@sistina.com List-Help: List-Post: List-Subscribe: , List-Unsubscribe: , List-Archive: Date: Mon Nov 17 12:45:02 2003 List-Id: Content-Type: text/plain; charset="us-ascii" To: neuron >> No, that is true. Your low read speed does indicate that you are >> not using DMA. Give us the output of "hdparm /dev/hda". Also a >> simple benchmark is to do "dd_rescue /dev/hda /dev/null". What does >> that give you in numbers? > /dev/hdd: > multcount = 16 (on) > IO_support = 1 (32-bit) > unmaskirq = 0 (off) > using_dma = 1 (on) > keepsettings = 0 (off) > readonly = 0 (off) > readahead = 8 (on) > geometry = 14589/255/63, sectors = 234375000, start = 0 This looks good. You could try -c3 to enable 32-bit w/sync and also enable Write cache -W1 (this may and many not be wise in case you have power failures often). > the cables are new (I thought that they may be a problem), I've > gotten far better speeds on the same system and a worse system > before I used lvm on the same drives. I REALLY doubt there's > something wrong with the drives (I replaced one of them because of > an error, and looked for trouble after replacing that one, but > didn't find anything else). > And that dd_rescue will read from /dev/hda and write to /dev/null > right? Meaning it's a read test, and not a write test (= I won't > loose any data on it ;) ). Yes, it is a read-only test! Read the manpage to get all flags you can use with it (such as how big blocks it is to read etc). > _______________________________________________ > linux-lvm mailing list > linux-lvm@sistina.com > http://lists.sistina.com/mailman/listinfo/linux-lvm > read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/