From owner-freebsd-fs@FreeBSD.ORG Mon Jan 11 23:29:55 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 3B5C0106566B; Mon, 11 Jan 2010 23:29:55 +0000 (UTC) (envelope-from kmatthew.macy@gmail.com) Received: from mail-pz0-f202.google.com (mail-pz0-f202.google.com [209.85.222.202]) by mx1.freebsd.org (Postfix) with ESMTP id 054258FC19; Mon, 11 Jan 2010 23:29:54 +0000 (UTC) Received: by pzk40 with SMTP id 40so827134pzk.7 for ; Mon, 11 Jan 2010 15:29:54 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:sender:reply-to:received :in-reply-to:references:date:x-google-sender-auth:message-id:subject :from:to:cc:content-type:content-transfer-encoding; bh=WWCC5qLzjoPtt0FDCKXcR2Gs47AL1T5f4gLtiwgmq8c=; b=rmyGkw2RXckqZyBE2/MhDcb6nWaliRHFbkYgv6x3uT5YPD4wvWwrqKGNszwfeXY0GP jAykegYkkUEtjQMXjDbfWxSa6Ja6ajewE5TLCAHeEiWpryBz3rScCx4wDtsBYyD33/9Z CK4+3pHDulzh57PZbSOT4n7K88yJRvT6nncjU= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:sender:reply-to:in-reply-to:references:date :x-google-sender-auth:message-id:subject:from:to:cc:content-type :content-transfer-encoding; b=BUfG6hvr12LCiqOWN0fuJyLKYTh5tOohiBOxG+wJ/IeN/5sf+j+BNai7uiO/C9VZsQ vQeK8FgVolZ7wVjdLVAo1fdH+yjNtS/FMHtTPF8FF0SyNkiNANpJ1siu/O7/jNM4qpSx 7eNfZp6iCqXFL7wyqh3/hn5I9JU0Ennxa9WCY= MIME-Version: 1.0 Sender: kmatthew.macy@gmail.com Received: by 10.115.26.7 with SMTP id d7mr4343810waj.12.1263252594642; Mon, 11 Jan 2010 15:29:54 -0800 (PST) In-Reply-To: References: <20100110161206.GA86684@plebeian.afflictions.org> <20100110184612.GC86684@plebeian.afflictions.org> Date: Mon, 11 Jan 2010 15:29:54 -0800 X-Google-Sender-Auth: a1a2555c6bcea339 Message-ID: <82c4140e1001111529u7d7ac409h63dda4cc10b76522@mail.gmail.com> From: "K. Macy" To: Dan Naumov Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Cc: freebsd-fs@freebsd.org, Damian Gerow , FreeBSD-STABLE Mailing List Subject: Re: ZFS on top of GELI X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list Reply-To: kmacy@freebsd.org List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 11 Jan 2010 23:29:55 -0000 >> >> If performance is an issue, you may want to consider carving off a parti= tion >> on that SSD, geli-fying it, and using it as a ZIL device. =A0You'll prob= ably >> see a marked performance improvement with such a setup. > > That is true, but using a single device for a dedicated ZIL is a huge > no-no, considering it's an intent log, it's used to reconstruct the > pool in case of a power failure for example, should such an event > occur at the same time as a ZIL provider dies, you lose the entire > pool because there is no way to recover it, so if ZIL gets put > "elsewhere", that elsewhere really should be a mirror and sadly I > don't see myself affording to use 2 SSDs for my setup :) > This is false. The ZIL is used for journalling synchronous writes. If your ZIL is lost you will lose the data that was written to the ZIL, but not yet written to the file system proper. Barring disk corruption, the file system is always consistent. -Kip