From mboxrd@z Thu Jan 1 00:00:00 1970 From: =?ISO-8859-15?Q?Jo=E3o_Eduardo_Lu=EDs?= Subject: Re: Strange write behavior on an osd Date: Tue, 24 Apr 2012 17:31:42 +0100 Message-ID: <4F96D56E.1080205@gmail.com> References: <4F96B971.5050806@tuxadero.com> <4F96C557.4090603@gmail.com> <4F96CF81.4030707@tuxadero.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enig72FB958BBF89F5BC89E4E6A2" Return-path: Received: from mail-bk0-f46.google.com ([209.85.214.46]:37971 "EHLO mail-bk0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755438Ab2DXQbq (ORCPT ); Tue, 24 Apr 2012 12:31:46 -0400 Received: by bkuw12 with SMTP id w12so629872bku.19 for ; Tue, 24 Apr 2012 09:31:45 -0700 (PDT) In-Reply-To: <4F96CF81.4030707@tuxadero.com> Sender: ceph-devel-owner@vger.kernel.org List-ID: To: Martin Mailand Cc: ceph-devel@vger.kernel.org This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enig72FB958BBF89F5BC89E4E6A2 Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: quoted-printable On 04/24/2012 05:06 PM, Martin Mailand wrote: > Hi, >=20 > Am 24.04.2012 17:23, schrieb Jo=E3o Eduardo Lu=EDs: >> Any chance you could run iotop during the busy periods and tell us whi= ch >> processes are issuing the io? >=20 > sure, > http://85.214.49.87/ceph/iotop.txt >=20 > -martin >=20 I don't want to rush into a definite answer, but it looks like the IO bursts are caused by btrfs. The periods on which they happen are consistent with btrfs' internal thread scheduling (which are fired every 30 seconds), and from iotop it would seem as if they're the ones responsible for all the IO when it jumps from the "couple of MB/s" mark to "several hundreds of MB/s". I've seen it happen before, although on synthetic and very specific workloads. Not sure on what may be the cause in your case though. What kernel and btrfs versions are you using? --=20 Jo=E3o Eduardo Lu=EDs gpg key: 477C26E5 from pool.keyserver.eu --------------enig72FB958BBF89F5BC89E4E6A2 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iQEcBAEBAgAGBQJPltVuAAoJEJ9vvxhHfCblWoIH+wcWGgRm9vleyxWPibGG1SKt cU16p+CYAypVafzMiIQAlvgv2tuxpxb4Y2unfyvTySZbhBzcdkLjwq1s5axWP/TP wHQfeYy2LiFMXwlBHexxYZ7fD+j/RSvkiUTO+zTlO2gKX5ukhMuM2535+kxHNxLC L4OziAMbwhkbVIiudx4axFCh/AxF8Pf6Ra7y9fAP6YIfLuzhaLhJC2w70Gml6tza Iccii8LZEOfvrC2iQE1wJ16qtz3KqUjziuPbSHNu2o4C/sEQVspQ+PO8NCCNVKeW 1BXCX49piDn0Pv6W5kJqLzG8GlbBPKJkRE8oDNcCyUoZwsmp5RvmTSaYJysP8lM= =5loe -----END PGP SIGNATURE----- --------------enig72FB958BBF89F5BC89E4E6A2--