From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Arie Bant@mail.com" Subject: Re: [linux-lvm] performance comparison soft-hardware RAID + LVM: bad Message-ID: <014f01c27563$478fe560$28bf18ac@abant.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7bit In-Reply-To: <20021016085753.20974.47952.Mailman@hermes.sistina.com> 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: Wed Oct 16 22:47:01 2002 List-Id: Content-Type: text/plain; charset="us-ascii" To: linux-lvm@sistina.com Cc: 'Jon Bendtsen' -----Original Message----- Date: Wed, 16 Oct 2002 10:34:41 +0200 From: Jon Bendtsen Organization: Silicide A/S To: linux-lvm@sistina.com Subject: Re: [linux-lvm] performance comparison soft-hardware RAID + LVM: bad Reply-To: linux-lvm@sistina.com You dont have enough disks, 2 disks might be a widely used common setup, but other people use more disks, like 4, 8, ... especialy when using scsi, which for some reason doesnt seem to contain as much as IDE disks. Jon, Availability of large SCSI hard disks has nothing to do with it. Using more spindles is better for performance as a general rule (more spindles can lead to less head movement, if properly configured, head movement/rotational delay counts for most of the access time on hard disks. Also, via SCSI, seeks can be done simultaneously and in overlap with I/O on other hard disks and/or processor activity), hence you will find that in SCSI configurations more disks are used for performance reasons. For this reason only, I keep a stack of, now old, 1/2/4 GB drives to use as dedicated swap devices and /tmp file systems. Given the intrinsic limitations, all this is not possible when using IDE, so the capacity than has to come from large disks, the performance will suffer accordingly, especially in total system throughput. One of a number of reasons why you should always go with SCSI when you want performance. Regards, Arie Bant.