From owner-freebsd-fs@FreeBSD.ORG Wed Jul 3 11:21:29 2013 Return-Path: Delivered-To: freebsd-fs@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115]) by hub.freebsd.org (Postfix) with ESMTP id DF943949 for ; Wed, 3 Jul 2013 11:21:29 +0000 (UTC) (envelope-from berend@pobox.com) Received: from smtp.pobox.com (b-pb-sasl-quonix.pobox.com [208.72.237.35]) by mx1.freebsd.org (Postfix) with ESMTP id A72691F66 for ; Wed, 3 Jul 2013 11:21:29 +0000 (UTC) Received: from smtp.pobox.com (unknown [127.0.0.1]) by b-sasl-quonix.pobox.com (Postfix) with ESMTP id 3DFCD2DE62; Wed, 3 Jul 2013 11:21:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha1; c=relaxed; d=pobox.com; h=date :message-id:from:to:cc:subject:in-reply-to:references :mime-version:content-type:content-transfer-encoding; s=sasl; bh=bpKPzsR/LfKEZOBbr1eXEmJruzU=; b=MWeoqMMBunJJasvuc4Az7VgxcpT8 kpfmyXOuoE5jMvMtjnKJ94YgbqVCnl4Mw5i21NfKsxuVOVIUSN+N+udkiritvTtS He9+HtgEosZJVUbjgC7gcPJ6q/L3e++yvBxUcYSft1To6BFQZsC/14oGPXW5GMXl TUwUvImjuPcIwjg= DomainKey-Signature: a=rsa-sha1; c=nofws; d=pobox.com; h=date:message-id :from:to:cc:subject:in-reply-to:references:mime-version :content-type:content-transfer-encoding; q=dns; s=sasl; b=kEJLVJ x+/Qg0c0WjTklQ8FcQqGJ9ADb8vTQOZWzsgm/EgOHxEf0QCfZK0NSChokbw3E1jI efOthP2C3vRuMMGmU286yjF3WS/U6+xgnSb8cosUUQ6WJ39UMSs3AlwcN04sbc8L gbhkUUszG+vA6I9oBeNQj1YJplQcSivJQkPno= Received: from b-pb-sasl-quonix.pobox.com (unknown [127.0.0.1]) by b-sasl-quonix.pobox.com (Postfix) with ESMTP id 347072DE61; Wed, 3 Jul 2013 11:21:27 +0000 (UTC) Received: from bmach.nederware.nl (unknown [27.252.247.84]) by b-sasl-quonix.pobox.com (Postfix) with ESMTPA id 583372DE5E; Wed, 3 Jul 2013 11:21:26 +0000 (UTC) Received: from quadrio.nederware.nl (quadrio.nederware.nl [192.168.33.13]) by bmach.nederware.nl (Postfix) with ESMTP id 492CD5C5B; Wed, 3 Jul 2013 23:21:19 +1200 (NZST) Received: from quadrio.nederware.nl (quadrio.nederware.nl [127.0.0.1]) by quadrio.nederware.nl (Postfix) with ESMTP id DBA794A11BF3; Wed, 3 Jul 2013 23:21:23 +1200 (NZST) Date: Wed, 03 Jul 2013 23:21:23 +1200 Message-ID: <87ppuz51os.wl%berend@pobox.com> From: Berend de Boer To: Markus Gebert Subject: Re: EBS snapshot backups from a FreeBSD zfs file system: zpool freeze? In-Reply-To: References: <87li5o5tz2.wl%berend@pobox.com> <87ehbg5raq.wl%berend@pobox.com> <20130703055047.GA54853@icarus.home.lan> <6488DECC-2455-4E92-B432-C39490D18484@dragondata.com> <14A2336A-969C-4A13-9EFA-C0C42A12039F@hostpoint.ch> <87zju43sxl.wl%berend@pobox.com> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL/10.8 EasyPG/1.0.0 Emacs/24.3 (i686-pc-linux-gnu) MULE/6.0 (HANACHIRUSATO) Organization: Xplain Technology Ltd MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Content-Type: multipart/signed; boundary="pgp-sign-Multipart_Wed_Jul__3_23:21:23_2013-1"; micalg=pgp-sha256; protocol="application/pgp-signature" Content-Transfer-Encoding: 7bit X-Pobox-Relay-ID: B333D710-E3D2-11E2-8D06-E84251E3A03C-48001098!b-pb-sasl-quonix.pobox.com Cc: freebsd-fs X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 03 Jul 2013 11:21:29 -0000 --pgp-sign-Multipart_Wed_Jul__3_23:21:23_2013-1 Content-Type: text/plain; charset=US-ASCII >>>>> "Markus" == Markus Gebert writes: Markus> Of course it'd be safest to EBS snapshot all disk at the Markus> same exact time, but if I understand you correctly, there Markus> is no such functionality and the OS is expected to Markus> guarantee some kind of consistency between multiple Markus> related disks. That's exactly the point. I agree with you that the one disk solution is trivial. It's the multiple disk case that concerns me. Markus> Yes, but a zfs snapshot is near instant. ioctl, wait for Markus> sync, mark clean, trigger EBS snapshot, ioctl again to Markus> resume IO, sounds like more work. Definitely true. Could take a few seconds if you have a lot of disks. But a hickup of can't write for a few seconds isn't noticeable in most situations. And after you have done your zfs snapshot, you're not done either! You have to transfer it somewhere, probably compressed, so your (p)bzip2 dominates your CPUs, your network bandwidth is gone, etc. So a backup starts to becomes a really high impact event, while an EBS snapshot today isn't a big deal. Slightly degraded performance perhaps, but not much. -- All the best, Berend de Boer ------------------------------------------------------ Awesome Drupal hosting: https://www.xplainhosting.com/ --pgp-sign-Multipart_Wed_Jul__3_23:21:23_2013-1 Content-Type: application/pgp-signature Content-Transfer-Encoding: 7bit Content-Description: OpenPGP Digital Signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.17 (GNU/Linux) iQIcBAABCAAGBQJR1AkzAAoJEKOfeD48G3g5guQP+wcyXSEU4hWRFqmft5NmzSZq 8O/cAyAbJruyhVViMuEQFT/zgVCAhhDNt/HwQMJWIgNdyiRkX+p+jg6RqwQ4Q7tZ I8jLfMxHQhUYJhE59Vh5wfw6syPvqOjeoDpY04mfLZ8E2JfVNiibJGAWkxCRagIj IBm4HGSbxgrgD3ZR4WIdZpkY8ZeStL4NyeIPcbiu3aJzzAoW21fPkiCXZJ7eQ3Fx g9SkyhhF95+A8CShhsz/QzzYGniGAoPWd1vNJ8P8dL1A3FPRgqh3u+OKj4F3jBvq 0+S1iu4mNBik8o8I7lYa5LxDx9ydHaKNwcLBStkHySGiK4snHCKRWj6bMBdHgTP7 JHe679Hdf70ik2unbWO+tnh/Hh93NsR9OsIDcr6Zep+QUJHANQe6XUV3Or/7N+xD fY1GVnR6yq0YRKtoCk3pAfwNivKNO/9iT0CPvb3eZ3b3dc2zjtKs7hPcff8mou2l BZpRmlusN8u4BQDg799G9y8do01bef0T32E7NJYqNj0pqrbHjg12l7Wq3xBCFwyt F2oU8BT4UXA2rNXnz4+P0sjNm7hKR7paAsZmh/2PJDC+8FBAyiDVbBVrId1MF7tr w+VUBqHITSUlnsO1dctj3M18zc1GypCWgL7F+eWAnptyz9+gHn+AoFWBeyGzdFex dPKQwscCfcIgDENKBUc7 =SrOz -----END PGP SIGNATURE----- --pgp-sign-Multipart_Wed_Jul__3_23:21:23_2013-1--