From mboxrd@z Thu Jan 1 00:00:00 1970 From: Brad Campbell Subject: Re: Implementing Global Parity Codes Date: Tue, 30 Jan 2018 22:18:34 +0800 Message-ID: <867daa46-ac15-a0a2-8809-89af882ad3a4@fnarfbargle.com> References: <5A6C3A43.6030701@youngman.org.uk> <5A6C972C.8070401@youngman.org.uk> <5A6F5D9B.5060201@youngman.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <5A6F5D9B.5060201@youngman.org.uk> Content-Language: en-US Sender: linux-raid-owner@vger.kernel.org To: Wols Lists Cc: linux-raid@vger.kernel.org List-Id: linux-raid.ids On 30/01/18 01:44, Wols Lists wrote: > Except that most drives don't do that nowadays, they do "constant linear > velocity" so the drive speeds up or slows down depending on where the > heads are, I believe. No. Hard disks have one speed. That can be easily proven by popping the top off and putting a tacho on the spindle, or just looking at any linear read benchmark as they all demonstrate that data transfer slows down as the head works its way towards the spindle. Same reason the first couple of tracks on each LP sounded better. More vinyl to get a better response. Optical disks used CLV where they needed to get bits out at a specific clock rate (ie Audio). Brad.