From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marc MERLIN Subject: Can reading a raid drive trigger all the other drives in that set? Date: Tue, 28 Jun 2011 09:22:05 -0700 Message-ID: <20110628162205.GG20420@merlins.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline Sender: linux-raid-owner@vger.kernel.org To: linux-raid@vger.kernel.org List-Id: linux-raid.ids I have ext4 over lvm2 on a sw raid5 with 2.6.39.1 In order to save power I have my drives spin down. When I access my filesystem mount point, I get hangs of 30sec or a bit more as each and every drive are woken up serially. Is there any chance to put a patch in the block layer so that when it gets a read on a block after a certain timeout, it just does one dummy read on all the other droves in parallel so that all the drives have a chance to spin back up at the same time and not serially? Thanks, Marc -- "A mouse is a device used to point at the xterm you want to type in" - A.S.R. Microsoft is to operating systems .... .... what McDonalds is to gourmet cooking Home page: http://marc.merlins.org/