From owner-freebsd-fs@FreeBSD.ORG Tue Oct 19 04:53:42 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 2DCFF10656CD; Tue, 19 Oct 2010 04:53:42 +0000 (UTC) (envelope-from zbeeble@gmail.com) Received: from mail-gw0-f54.google.com (mail-gw0-f54.google.com [74.125.83.54]) by mx1.freebsd.org (Postfix) with ESMTP id CA3CC8FC08; Tue, 19 Oct 2010 04:53:40 +0000 (UTC) Received: by gwb20 with SMTP id 20so948780gwb.13 for ; Mon, 18 Oct 2010 21:53:40 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:received:received:in-reply-to :references:date:message-id:subject:from:to:cc:content-type; bh=TfuOzPBpAQdwER/m5XETh3VMIxD0CUt5yAgd0b5y4Ic=; b=QdTT8HwvxrCQCXI033FUqbCCzTozgBAXzoQ3q83vCikwAsw4vp3SDBiaSim/m0ver2 SRcZqfvROi68Xr6duZolIhe6Jd2hn8mOCNpGkXbR2ESf5e5M/L2pt+5CQXAFyci5zXEG flr0ezWukG+FPGVve5d0zfeFoEqKl61HjNk+c= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type; b=NlvZP0i1EYTyVyf9KR+V5cvH9rpMtOvWNqWHfxBDzvivBHH/SMih4IKOI/H8UzaEtr RlSProYRy/ee+CYYERvSsHw166BHsaTUF7xUqMEMthSWNrFsN7Q+vo2ughMfmtvA0fH5 AMZgL42iwaV1Rko8bHSY+Gj/kJ0y91LBubPtQ= MIME-Version: 1.0 Received: by 10.150.52.18 with SMTP id z18mr8279445ybz.189.1287464018301; Mon, 18 Oct 2010 21:53:38 -0700 (PDT) Received: by 10.151.82.1 with HTTP; Mon, 18 Oct 2010 21:53:38 -0700 (PDT) In-Reply-To: <20101018222611.GC2375@garage.freebsd.pl> References: <20101016222833.GA6765@garage.freebsd.pl> <20101018222611.GC2375@garage.freebsd.pl> Date: Tue, 19 Oct 2010 00:53:38 -0400 Message-ID: From: Zaphod Beeblebrox To: Pawel Jakub Dawidek Content-Type: text/plain; charset=ISO-8859-1 Cc: freebsd-fs@freebsd.org Subject: Re: Converting a non-HAST ZFS pool to a HAST pool 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: Tue, 19 Oct 2010 04:53:42 -0000 I'm wondering if I'm missing something here --- because I'm wondering if running HAST under ZFS isn't a step backwards. My quick read of HAST seems to indicate that it's going to manage two disks and present them as one disk to ZFS. The design problem with this (especially since we're talking a _lot_ of network (and memory) transfers involved) is data corruption --- the idea that ZFS protects data better when it can determine one disk has it right while another disk has it wrong (as it can when it manages the two disks). Wouldn't it be better to just have network (iscsi-like) spools attached to ZFS? Individual spools could still fail. What am I missing? Is there a better description of HAST than the FreeBSD wiki page?