From owner-freebsd-fs@FreeBSD.ORG Fri Feb 5 19:51:20 2010 Return-Path: Delivered-To: freebsd-fs@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 06231106566B; Fri, 5 Feb 2010 19:51:20 +0000 (UTC) (envelope-from lopez.on.the.lists@yellowspace.net) Received: from mail.yellowspace.net (mail.yellowspace.net [80.190.200.164]) by mx1.freebsd.org (Postfix) with ESMTP id 4B4F78FC1B; Fri, 5 Feb 2010 19:51:19 +0000 (UTC) Received: from furia.intranet ([93.104.43.176]) (AUTH: LOGIN lopez.on.the.lists@yellowspace.net) by mail.yellowspace.net with esmtp; Fri, 05 Feb 2010 20:51:16 +0100 id 0036A17F.000000004B6C76B4.0000655E Mime-Version: 1.0 (Apple Message framework v1077) Content-Type: text/plain; charset=us-ascii From: Lorenzo Perone In-Reply-To: <20100204210522.GB1733@garage.freebsd.pl> Date: Fri, 5 Feb 2010 20:51:15 +0100 Content-Transfer-Encoding: 7bit Message-Id: <25CA86F9-4B63-44FE-8A03-855DC1D4DF60@yellowspace.net> References: <914E8A1F-2FE9-4A7E-9BC7-6174402B57D3@yellowspace.net> <20100128132613.olxiwcq0go0g0w88@www.hmallett.co.uk> <9B1DF836-0CCC-4CB2-B83C-3040428A7344@yellowspace.net> <20100204210522.GB1733@garage.freebsd.pl> To: Pawel Jakub Dawidek X-Mailer: Apple Mail (2.1077) Cc: freebsd-fs@freebsd.org Subject: Re: Any news on the HAST Project? X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 05 Feb 2010 19:51:20 -0000 On 04.02.2010, at 22:05, Pawel Jakub Dawidek wrote: > Every write request is handled synchronously by HAST. It is reported as > completed only when it is stored on local and on remote node. That's great for state - yet it also means that it won't be suitable for some scenarios - such as secondaries connected over slow links or with noticeably slower media. While I sort of imagine some of the tricky, messy implications of an aynchronous implementation, I was hoping for it somehow. That doesn't make HAST less magic - it just shifts its use to different scenarios than some I originally imagined, were it was something more similar to what dfly's is doing with hammer mirror-stream - but at a filesystem-agnostic level (wonder if that's even possible in theory).. > This also makes ZFS great choice for running on HAST as 'zpool import' > is very fast as oppose to fsck (at least until Jeff finish his SU+J > project). This sounds like great marriage. Could latency be further enhanced by HASTing the pool geoms and using an 'unHASTed' device as ZIL device, in theory (as soon as that's possible)? Thanx a lot! Regards, Lorenzo