From: "J. Bruce Fields" Subject: Re: mountd prevents spindown of non-exported disk Date: Mon, 25 Feb 2008 11:32:47 -0500 Message-ID: <20080225163247.GA10402@fieldses.org> References: <47BCA119.2030404@foo-lounge.de> <18364.64328.189954.417159@notabene.brown> <47C2CFB1.4000004@foo-lounge.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Neil Brown , linux-nfs@vger.kernel.org To: Timo Reimann Return-path: Received: from mail.fieldses.org ([66.93.2.214]:55670 "EHLO fieldses.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755382AbYBYQcw (ORCPT ); Mon, 25 Feb 2008 11:32:52 -0500 In-Reply-To: <47C2CFB1.4000004-d4LLFNs4DFRA7UZ8SB9NFg@public.gmane.org> Sender: linux-nfs-owner@vger.kernel.org List-ID: On Mon, Feb 25, 2008 at 03:24:49PM +0100, Timo Reimann wrote: > Neil Brown wrote: > > On Wednesday February 20, mailinglist-d4LLFNs4DFRA7UZ8SB9NFg@public.gmane.org wrote: > >> Although there should be nothing accessing the disk except my custom > >> backup cron job initiating at 5am daily, something was constantly > >> bringing it back into active state after a rough 20-25 minutes. With the > >> help of blktrace, I monitored every single I/O access to the disk and > >> found a single process only that would cause the wake-up: > >> > >> > >> $ sudo blkparse -i hda.blktrace.0 > >> Input file hda.blktrace.0 added > >> [...] > >> 3,0 0 6 88.950000000 6806 Q R 447 + 8 [rpc.mountd] > >> [...] > >> > >> > >> So for some reason, rpc.mountd issues this disk request in regular > >> intervals although nothing on the disk is being NFS-exported according > >> to /etc/exports. > > > > This is doubtlessly something related to libblkid. > > > > We only ever ask it for the UID of specific devices that have been > > exported. However it is quite possible that it touches other devices > > as well... > > > > I'm using libblkid in a way that it wasn't originally designed to be > > used. It was (as far as I can tell) designed to find a device given a > > UUID or similar. In that case you would expect it to touch every > > device. > > > > You could always build your own nfs-utils and configure with > > --without-uuid. > > I did so and re-compiled the nfs-utils package, resulting in new > packages of nfs-common and nfs-kernel-server under Ubuntu 7.10. > > However, another re-run of blktrace yielded that the problem did not go > away. There are still lots of disk accesses from mountd, and the strace > output continuously contains open calls to the unmounted backup filesystem. > > > Is there anything else I can do in attempt to resolve this issue? I > suppose pasting the complete output of strace might help, but I wouldn't > do so without explicit confirmation of yours as the log-file is 3.2 MB > large. Probably the most likely to read such an strace are me, Neil, and Steve (), so you might just send it privately to the three of us. --b.