From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pd0-f180.google.com ([209.85.192.180]:33437 "EHLO mail-pd0-f180.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753238AbbBIWYm (ORCPT ); Mon, 9 Feb 2015 17:24:42 -0500 Received: by pdbnh10 with SMTP id nh10so31676803pdb.0 for ; Mon, 09 Feb 2015 14:24:42 -0800 (PST) MIME-Version: 1.0 Date: Mon, 9 Feb 2015 17:24:42 -0500 Message-ID: Subject: btrfs raid5 with mixed disks From: Rich Freeman To: Btrfs BTRFS Content-Type: text/plain; charset=UTF-8 Sender: linux-btrfs-owner@vger.kernel.org List-ID: How does btrfs raid5 handle mixed-size disks? The docs weren't terribly clear on this. Suppose I have 4x3TB and 1x1TB disks. Using conventional lvm+mdadm in raid5 mode I'd expect to be able to fit about 10TB of space on those (2TB striped across 4 disks plus 1TB striped across 5 disks after partitioning). How much would btrfs be able to store in the same configuration? I did see something about being able to use fixed-size stripes, and I'm not sure if this helps. If it does, are there any penalties, especially with future expansion of the array? With raid1 mode btrfrs is reasonably smart about mixed disk sizes, and you usually end up with half of the total space available. -- Rich