From owner-freebsd-doc@FreeBSD.ORG Thu Mar 28 03:50:01 2013 Return-Path: Delivered-To: freebsd-doc@smarthost.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by hub.freebsd.org (Postfix) with ESMTP id EF43923E for ; Thu, 28 Mar 2013 03:50:00 +0000 (UTC) (envelope-from gnats@FreeBSD.org) Received: from freefall.freebsd.org (freefall.freebsd.org [IPv6:2001:1900:2254:206c::16:87]) by mx1.freebsd.org (Postfix) with ESMTP id D2C01689 for ; Thu, 28 Mar 2013 03:50:00 +0000 (UTC) Received: from freefall.freebsd.org (localhost [127.0.0.1]) by freefall.freebsd.org (8.14.6/8.14.6) with ESMTP id r2S3o0GF063160 for ; Thu, 28 Mar 2013 03:50:00 GMT (envelope-from gnats@freefall.freebsd.org) Received: (from gnats@localhost) by freefall.freebsd.org (8.14.6/8.14.6/Submit) id r2S3o0Ls063159; Thu, 28 Mar 2013 03:50:00 GMT (envelope-from gnats) Resent-Date: Thu, 28 Mar 2013 03:50:00 GMT Resent-Message-Id: <201303280350.r2S3o0Ls063159@freefall.freebsd.org> Resent-From: FreeBSD-gnats-submit@FreeBSD.org (GNATS Filer) Resent-To: freebsd-doc@FreeBSD.org Resent-Reply-To: FreeBSD-gnats-submit@FreeBSD.org, "Ronald F.Guilmette" Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by hub.freebsd.org (Postfix) with ESMTP id C178610B for ; Thu, 28 Mar 2013 03:42:04 +0000 (UTC) (envelope-from rfg@tristatelogic.com) Received: from outgoing.tristatelogic.com (segfault.tristatelogic.com [69.62.255.118]) by mx1.freebsd.org (Postfix) with ESMTP id A0E66646 for ; Thu, 28 Mar 2013 03:42:04 +0000 (UTC) Received: by segfault.tristatelogic.com (Postfix, from userid 1237) id 18BE73B3F7; Wed, 27 Mar 2013 20:42:04 -0700 (PDT) Message-Id: <20130328034204.18BE73B3F7@segfault.tristatelogic.com> Date: Wed, 27 Mar 2013 20:42:04 -0700 (PDT) From: "Ronald F.Guilmette" To: FreeBSD-gnats-submit@freebsd.org X-Send-Pr-Version: 3.113 Subject: docs/177431: Handbook & Announcements recommend poor dd options for memstick images Cc: rfg@tristatelogic.com X-BeenThere: freebsd-doc@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list Reply-To: "Ronald F.Guilmette" List-Id: Documentation project List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 28 Mar 2013 03:50:01 -0000 >Number: 177431 >Category: docs >Synopsis: Handbook & Announcements recommend poor dd options for memstick images >Confidential: no >Severity: non-critical >Priority: medium >Responsible: freebsd-doc >State: open >Quarter: >Keywords: >Date-Required: >Class: doc-bug >Submitter-Id: current-users >Arrival-Date: Thu Mar 28 03:50:00 UTC 2013 >Closed-Date: >Last-Modified: >Originator: Ronald F. Guilmette >Release: FreeBSD 9.1-RELEASE amd64 >Organization: entr0py >Environment: FreeBSD 9.1-RELEASE amd64 >Description: The Handbook, as shown on this web page: http://www.freebsd.org/doc/en/books/handbook/bsdinstall-pre.html recommends dd'ing the desired (?) memstick.img file to a USB memory stick using the following command: # dd if=FreeBSD-9.0-RELEASE-i386-memstick.img of=/dev/da0 bs=64k (Please note that the specific filename mentioned here is now out-of-date relative to the most recent -RELEASE.) So anyway, there appear to be two things wrong with the above recommended dd command, to wit: (1) the recommended dd block size of 64k is probably highly sub-optimal for many/most/all modern USB flash drives. It is apparently difficult to find a single (minimal) block size that will provide best per- formance for all USB flash drives, however online sources suggest that a 1 MiB block size should provide excelent performance for most such drives (and with relatively little waste of space). (2) The dd command should probably also include the conv=sync option, just as shown in the 9.1 RELEASE Announcement. (Otherwise it is not 100% clear what will happen to the last few blocks of the memstick.img file, i.e. the ones that don't fix neatly into exactly `N' of the dd blocks.) Separately and additionally, various versions of the official FreeBSD Release Announcements, for example the version found here: http://www.freebsd.org/releases/9.1R/announce.html recommend using bs=10240 when dd'ing a memstick.img file to a USB flash device. As noted above, this value is also probably highly sub-optimal, and should probably be replaced (in *all* current and past Release Announcement pages) to the value "bs=1M". >How-To-Repeat: Visit the two URLs mentioned above. >Fix: See above. >Release-Note: >Audit-Trail: >Unformatted: