From owner-freebsd-fs@freebsd.org Wed Apr 13 14:58:06 2016 Return-Path: Delivered-To: freebsd-fs@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id A2983B0FCA3 for ; Wed, 13 Apr 2016 14:58:06 +0000 (UTC) (envelope-from matthew@FreeBSD.org) Received: from smtp.infracaninophile.co.uk (smtp.infracaninophile.co.uk [81.2.117.100]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 60E791142 for ; Wed, 13 Apr 2016 14:58:06 +0000 (UTC) (envelope-from matthew@FreeBSD.org) Received: from zero-gravitas.local (unknown [85.199.232.226]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) (Authenticated sender: m.seaman@infracaninophile.co.uk) by smtp.infracaninophile.co.uk (Postfix) with ESMTPSA id 4B97211651 for ; Wed, 13 Apr 2016 14:57:56 +0000 (UTC) Authentication-Results: smtp.infracaninophile.co.uk; dmarc=none header.from=FreeBSD.org Authentication-Results: smtp.infracaninophile.co.uk/4B97211651; dkim=none; dkim-atps=neutral To: freebsd-fs@freebsd.org From: Matthew Seaman Subject: zpool scrub makes zfs get slow? Message-ID: <570E5E90.7060107@FreeBSD.org> Date: Wed, 13 Apr 2016 15:58:24 +0100 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.11; rv:38.0) Gecko/20100101 Thunderbird/38.6.0 MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="aFWt5r8pjleFi05DAAWV9ACtjvoXd0Qk5" X-Virus-Scanned: clamav-milter 0.99.1 at smtp.infracaninophile.co.uk X-Virus-Status: Clean X-Spam-Status: No, score=-0.4 required=5.0 tests=BAYES_00,RDNS_NONE, SPF_SOFTFAIL autolearn=no autolearn_force=no version=3.4.1 X-Spam-Checker-Version: SpamAssassin 3.4.1 (2015-04-28) on smtp.infracaninophile.co.uk X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 13 Apr 2016 14:58:06 -0000 This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --aFWt5r8pjleFi05DAAWV9ACtjvoXd0Qk5 Content-Type: multipart/mixed; boundary="U1D5aCBBcj7jIL4X5eaDX6fnniKlD9LLt" From: Matthew Seaman To: freebsd-fs@freebsd.org Message-ID: <570E5E90.7060107@FreeBSD.org> Subject: zpool scrub makes zfs get slow? --U1D5aCBBcj7jIL4X5eaDX6fnniKlD9LLt Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Part of our monitoring relies on running commands like: /sbin/zfs get -rHp -o value usedbysnapshots zroot through snmpd. We noticed today that this was timing out and it corresponded to a regular 'zpool scrub' starting up. While scrubbing is going on, that command can take in excess of a minute to return: % time /sbin/zfs get -rHp -o value usedbysnapshots zroot > /dev/null 0.298u 0.826s 1:08.62 1.6% 104+166k 47618+0io 0pf+0w % freebsd-version -ku 10.2-RELEASE-p9 10.2-RELEASE-p12 There's a large but not huge number of ZFSes in that pool: about 2500, and the drives are geli encrypted. Is this expected behaviour? Is there anything we can do to make 'zfs get' more snappy in these circumstances? Cheers, Matthew --U1D5aCBBcj7jIL4X5eaDX6fnniKlD9LLt-- --aFWt5r8pjleFi05DAAWV9ACtjvoXd0Qk5 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Comment: GPGTools - https://gpgtools.org iQJ8BAEBCgBmBQJXDl6WXxSAAAAAAC4AKGlzc3Vlci1mcHJAbm90YXRpb25zLm9w ZW5wZ3AuZmlmdGhob3JzZW1hbi5uZXQxOUYxNTRFQ0JGMTEyRTUwNTQ0RTNGMzAw MDUxM0YxMEUwQTlFNEU3AAoJEABRPxDgqeTnFhAQAIb13VzBnRc7uPVhVHFGrab9 EIu61OI4HWR/nt2kFpUOQ/MkOtFwXX2EW5tdC7BRpcTYf87o4jbeJ7oVCue4Ih5s 2Pzwv5r6M1sBkjXu8AiLdazLOXaxwtVoHD9meSNkVJ1unWv3E+wprrFVgB9DM1MO KGVKfetsNNRI6xifhuXZUcOIPrAqJZo6vz36QVNh3Bur7KOgum1dXt//sQ5HEri1 dzWFYdeXP2j9h6Plh5EnvzvcM7/vXEi0yRTjbY6wLixnV/G+OXMTl2LhuIq2vKWN UYoY9rPingy7lZxM7KOT5PYD7ULIVJ+6gnKymXsqUQo3g1WIAu/UD9fX8tf8kdFM BgiPM24RjN/DfpyzdVJM5cvXVoSzSTWSMMeo3fFLC/BjfZfeVaCKYyjPCPOIeUE8 Lfgl/+y/7gNePl49ayBFBQNDfrxqRTEIxzQFGJnriBRi2rgtyASsSycDlKb/kk/f zyzSTTLlgoR9O24AIe3YpiHOLtxrIdljHEX2uQmLRmvH7V0hF2Sy/+1/qZeam/vT GbNWX+Z9jZzhhc779G9yzOdxNZkv3O2WwhqWLEF6y1XKlKsVms+jVwCFS2CfuQFN v8GbMwhPp62I9I+Nr+rhle6dzj5DKY0FKXYSIgUsOAnwFphUqjuKo1Pjm4QO2JZV nwN47SCDGjojDPUQMkL9 =cZW/ -----END PGP SIGNATURE----- --aFWt5r8pjleFi05DAAWV9ACtjvoXd0Qk5--