From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from plane.gmane.org ([80.91.229.3]:47592 "EHLO plane.gmane.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757065AbaFYQBX (ORCPT ); Wed, 25 Jun 2014 12:01:23 -0400 Received: from list by plane.gmane.org with local (Exim 4.69) (envelope-from ) id 1WzpdR-0000ML-1n for linux-btrfs@vger.kernel.org; Wed, 25 Jun 2014 18:01:21 +0200 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 ; Wed, 25 Jun 2014 18:01:21 +0200 Received: from 1i5t5.duncan by ip68-231-22-224.ph.ph.cox.net with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Wed, 25 Jun 2014 18:01:21 +0200 To: linux-btrfs@vger.kernel.org From: Duncan <1i5t5.duncan@cox.net> Subject: Re: btrfs on whole disk (no partitions) Date: Wed, 25 Jun 2014 16:01:06 +0000 (UTC) Message-ID: References: <2316027.LZEnVG8laK@xev> <6CA8020B-EB92-4A44-8AA5-3F69709F81F2@colorremedies.com> <53A6DDAD.8070804@chinilu.com> <99AD3EFE-AF9A-44A1-912E-07B1E934239B@colorremedies.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-btrfs-owner@vger.kernel.org List-ID: Imran Geriskovan posted on Wed, 25 Jun 2014 15:01:49 +0200 as excerpted: > Note that gdisk gives default 8 sector alignment value for AF disks. > That is 'sector' meant by gdisk is 'Logical Sector'! > Sufficiently determined user may create misaligned partitions by playing > with alignment value and partition start/end values. AFAIK, for gdisk it's actually 2048 sector (1 MiB) alignment by default, on new devices or if you clear and redo the entire partition table. On pre-partitioned devices, gdisk will attempt to identify current alignment, but will set 8-sector alignment on devices > 300 GiB even where previous alignment vales are less than that. See the gdisk manpage under the "l" option for more. The same applies to cgdisk (under the Align option in its manpage). This has been the documented gdisk behavior for some versions now (I've been using it for awhile and remember when the default behavior changed), altho I'm referring to the 0.8.10 manpages for the version I have installed right now. Tho here, I started my first partition, the BIOS boot partition, at 1 MiB and made it 3 MiB in size, so it ends at 4 MiB, with everything beyond that 4 MiB aligned. The second partition is the EFI system partition, 124 MiB in size so ending at 128 MiB, with everything beyond that 128 MiB aligned. The next partition is /boot, 256 MiB, followed by a 640 MiB /var/log, ending at 1 GiB, with everything beyond that aligned on GiB boundaries. That makes for easier reconstruction should I lose both copies of the GPT partition table. Plus, as Linus says, "real men" publish it on the net and then use the net for backup, and I've posted my partition table several times, so if I need to I can just look it up in my postings right 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