From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from pigeon.gentoo.org ([208.92.234.80] helo=lists.gentoo.org) by finch.gentoo.org with esmtp (Exim 4.60) (envelope-from ) id 1RBysP-0005wO-Lx for garchives@archives.gentoo.org; Fri, 07 Oct 2011 01:05:26 +0000 Received: from pigeon.gentoo.org (localhost [127.0.0.1]) by pigeon.gentoo.org (Postfix) with SMTP id E154B21C0BE; Fri, 7 Oct 2011 01:05:11 +0000 (UTC) Received: from mail-qw0-f53.google.com (mail-qw0-f53.google.com [209.85.216.53]) by pigeon.gentoo.org (Postfix) with ESMTP id 8391D21C166 for ; Fri, 7 Oct 2011 01:04:18 +0000 (UTC) Received: by qafi31 with SMTP id i31so4787200qaf.40 for ; Thu, 06 Oct 2011 18:04:18 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type; bh=lJB8j/7k8KehIjy7gf+6eV1M8aYCR8Q0MOXcm+JEBqE=; b=Udx8M8M1rYYqRRohEhcPYrWWQvQrzANcTrGL6v+nbTNa6xnr/owmWnl8a4OIuoTu4S OjRihRqFO0XFJt0qV8aZeLqHzv+M7BQ2UxBfy8unlPZYg2VvpWYxvoav7i+pwNiLunY/ RW3RHZqbEAx3RKHHo5JomH2yXa4VymAIsyuX0= Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-Id: Gentoo Linux mail X-BeenThere: gentoo-user@lists.gentoo.org Reply-to: gentoo-user@lists.gentoo.org MIME-Version: 1.0 Received: by 10.224.217.199 with SMTP id hn7mr333677qab.48.1317949458010; Thu, 06 Oct 2011 18:04:18 -0700 (PDT) Received: by 10.224.80.209 with HTTP; Thu, 6 Oct 2011 18:04:17 -0700 (PDT) In-Reply-To: References: <4E8DFE1B.6060403@gmail.com> Date: Thu, 6 Oct 2011 18:04:17 -0700 Message-ID: Subject: Re: [gentoo-user] How can I power disk off? From: Mark Knecht To: gentoo-user@lists.gentoo.org Content-Type: text/plain; charset=UTF-8 X-Archives-Salt: X-Archives-Hash: 2dd2b37ffa453c90d0172b5b8f6e27d0 On Thu, Oct 6, 2011 at 1:28 PM, Michael Mol wrote: > On Thu, Oct 6, 2011 at 4:21 PM, Mark Knecht wrote: >> On Thu, Oct 6, 2011 at 1:03 PM, Paul Hartman >> My worry was that if the mdraid daemon saw one drive gone - either >> when starting to spin down or when one spins up slowly - and if mdraid >> didn't understand that all this stuff was taking place intentionally >> then it might mark that drive as having failed. > > Does mdraid even have an awareness of timeouts, or does it leave that > to lower drivers? I think the latter condition is more likely. > > I suspect, though, that if your disk fails to spin up reasonably > quickly, it's already failed. > In general I agree. However drives that are designed for RAID have a feature known as Time Limited Error Recovery (TLER) which supposedly guarantees that they'll get the drive back to responding fast enough to not have it marked as failed in the RAID array: http://en.wikipedia.org/wiki/Time-Limited_Error_Recovery When I built my first RAID I bought some WD 1TB green drives, built the RAID and immediately had drives failing because they didn't have this sort of feature. I replaced them with RAID Edition drives that have the TLER feature and have never had a problem since. (Well, I actually bought all new drives and kept the six 1TB drives which I'd mostly used up for other things like external eSATA backup drives, etc...) Anyway, I'm possibly over sensitized to this sort of timing problem specifically in a RAID which is why I asked the question of Paul in the first place. Cheers, Mark