From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from plane.gmane.org ([80.91.229.3]:47300 "EHLO plane.gmane.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751829Ab3KSVFK (ORCPT ); Tue, 19 Nov 2013 16:05:10 -0500 Received: from list by plane.gmane.org with local (Exim 4.69) (envelope-from ) id 1VisTt-0002JY-R9 for linux-btrfs@vger.kernel.org; Tue, 19 Nov 2013 22:05:09 +0100 Received: from ip68-231-22-224.ph.ph.cox.net ([68.231.22.224]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Tue, 19 Nov 2013 22:05:09 +0100 Received: from 1i5t5.duncan by ip68-231-22-224.ph.ph.cox.net with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Tue, 19 Nov 2013 22:05:09 +0100 To: linux-btrfs@vger.kernel.org From: Duncan <1i5t5.duncan@cox.net> Subject: Re: Actual effect of mkfs.btrfs -m raid10 ... -d raid10 ... Date: Tue, 19 Nov 2013 21:04:49 +0000 (UTC) Message-ID: References: <20131119090602.GV4315@carfax.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-btrfs-owner@vger.kernel.org List-ID: deadhorseconsulting posted on Tue, 19 Nov 2013 13:24:01 -0600 as excerpted: > Interesting, this confirms what I was observing. > Given the wording in man pages for "-m" and "-d" which states "Specify > how the metadata or data must be spanned across the devices specified." > I took "devices specified" to literally mean the devices specified after > the according switch. It's all in how you read the documentation. After years of doing so... While I can see how you might get that from reading the -m and -d option text descriptions, the synopsis indicates differently (excerpt quotes reformatted for posting): SYNOPSIS mkfs.btrfs [ -A alloc-start ] [ -b byte-count ] [ -d data-profile ] [ -f ] [ -n node‐size ] [ -l leafsize ] [ -L label ] [ -m metadata profile ] [ -M mixed data+metadata ] [ -s sectorsize ] [ -r rootdir ] [ -K ] [ -O feature1,feature2,... ] [ -h ] [ -V ] device [ device ... ] Here, you can see that the -d and -m options take only a single parameter, the profile, and that the device list goes at the end and is thus a general device list, not specifically linked to the -d and -m options. Similarly, the option lines themselves: -d, --data type -m, --metadata profile ... not... -d, --data type [ device [ device ... ]] -m, --metdata profile [ device [ device ...]] Those are from the manpage. Similarly, the usage line from the output of mkfs.btrfs --help (--help being an unrecognized option it says, but it does what it needs to do...): usage: mkfs.btrfs [options] dev [ dev ... ] options: -d --data data profile, raid0, raid1, raid5, raid6, raid10, dup or single -m --metadata metadata profile, values like data profile All options come first, no indication of per-option device list, then the general purpose devices list. So I'd argue that the documentation's reasonably clear as-is, no per- option device list, general purpose device list at the end, thus no ability to specify data-specific and metadata-specific device lists. (Of course it can happen that the code gets out of sync with the documentation, but that wasn't the argument here.) -- Duncan - List replies preferred. No HTML msgs. "Every nonfree program has a lord, a master -- and if you use the program, he is your master." Richard Stallman