From owner-freebsd-stable@FreeBSD.ORG Mon Oct 13 19:19:11 2014 Return-Path: Delivered-To: freebsd-stable@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 92137D7 for ; Mon, 13 Oct 2014 19:19:11 +0000 (UTC) Received: from thyme.infocus-llc.com (thyme.infocus-llc.com [199.15.120.10]) (using TLSv1 with cipher DHE-RSA-CAMELLIA256-SHA (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 6554426C for ; Mon, 13 Oct 2014 19:19:11 +0000 (UTC) Received: from draco.over-yonder.net (c-75-65-60-66.hsd1.ms.comcast.net [75.65.60.66]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by thyme.infocus-llc.com (Postfix) with ESMTPSA id D27FD37B587; Mon, 13 Oct 2014 14:19:03 -0500 (CDT) Received: by draco.over-yonder.net (Postfix, from userid 100) id 3jGqSR2D4Mz1Q2; Mon, 13 Oct 2014 14:19:03 -0500 (CDT) Date: Mon, 13 Oct 2014 14:19:03 -0500 From: "Matthew D. Fuller" To: freebsd-stable Subject: Re: getting to 4K disk blocks in ZFS Message-ID: <20141013191903.GR2161@over-yonder.net> References: <540FF3C4.6010305@ish.com.au> <54100258.2000505@freebsd.org> <5410F0B4.9040808@ish.com.au> <543C1E7B.4090204@bluerosetech.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <543C1E7B.4090204@bluerosetech.com> X-Editor: vi X-OS: FreeBSD User-Agent: Mutt/1.5.23-fullermd.4 (2014-03-12) X-Virus-Scanned: clamav-milter 0.98.4 at thyme.infocus-llc.com X-Virus-Status: Clean Cc: Steven Hartland X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.18-1 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 13 Oct 2014 19:19:11 -0000 On Mon, Oct 13, 2014 at 11:48:27AM -0700 I heard the voice of Darren Pilgrim, and lo! it spake thus: > > If the default is 4k and (for the limited time they're still common) > you use true 512b disks, you can waste space. Sure, but how much > space? The median file in /usr/ports is 408 bytes. Over 90% of the files are under 2k, which means the wastage for them is over 100% (before counting what gain compression might get). A little offhand mathery says it's about 78% extra overhead on the whole. And that includes the almost hundred megs (over 22% of the total size of the FS) for the INDEX.db, plus the ~90 megs of the flat INDEX files (another 20%). If you pull those out, the overhead is 130%. (To be sure, relatively few people have ports trees eating most of their space, but still; it's pretty pathological. I for one did decide some years back to always force 4k on any new FSen to make future life simpler, accepting the bloat, but it's there.) -- Matthew Fuller (MF4839) | fullermd@over-yonder.net Systems/Network Administrator | http://www.over-yonder.net/~fullermd/ On the Internet, nobody can hear you scream.