From mboxrd@z Thu Jan 1 00:00:00 1970 From: sensille Subject: Re: ENOSPC on heterogeneous raid 0 Date: Sun, 12 Dec 2010 17:18:04 +0100 Message-ID: <4D04F5BC.7070800@gmx.net> References: <201012121524.59737.hka@qbs.com.pl> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Cc: Hubert Kario , William Sheffler , linux-btrfs@vger.kernel.org To: cwillu Return-path: In-Reply-To: List-ID: cwillu wrote: > On Sun, Dec 12, 2010 at 8:24 AM, Hubert Kario wrote: >> On Wednesday 08 of December 2010 22:53:25 William Sheffler wrote: >>> Hello btrfs community. >>> >>> First off, thanks for all your hard work... I have been following >>> btrfs with interest for several years now and very much look forward >>> to the day it replaces ext4. The real killer feature (of btrfs >>> specifically) for me is the ability to add *and remove* devices from a >>> filesystem, as this allows rolling upgrades of my server's disks. I >>> have a 16 port 3ware 1650SE on which I have a number of small raid >>> units and it will be fantastic to be able to remove the oldest, >>> upgrade, and add the new storage back. I had previously been using >>> ZFS, but since ZFS doesn't allow removal of devices, this rolling >>> upgrade strategy doesn't work. >>> >>> My question is this: can btrfs handle striping (raid 0) across >>> heterogeneous devices? I seem to be losing any capacity on the larger >>> disk beyond what is available on the smaller disk. I really hope there >>> is some simple fix! >> Yes, it can handle stripping over devices of different size, unfortunately >> you're still limited to * >> >> if you want to use all the available space use "-d single" when creating >> volume >> >> for details, read the recent thread "800GB free, but no space left" > > If I'm not mistaken, -d single doesn't mean anything yet on a > multi-device system: you'll still get raid0. I don't think so. -d single does what it is expected to do. Also my recent patch makes allocation on multi-device setups much better, although it is not the last word on it.