From mboxrd@z Thu Jan 1 00:00:00 1970 From: Phil Turmel Subject: Re: linux raid wiki - backup files Date: Mon, 21 Nov 2016 09:07:35 -0500 Message-ID: <4febebb6-0442-cc5e-45d5-e041e21e2d95@turmel.org> References: <583077D0.5070804@youngman.org.uk> <5831B7B9.8090008@youngman.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <5831B7B9.8090008@youngman.org.uk> Sender: linux-raid-owner@vger.kernel.org To: Wols Lists , linux-raid List-Id: linux-raid.ids On 11/20/2016 09:48 AM, Wols Lists wrote: > On 20/11/16 00:27, Phil Turmel wrote: >> Yes. But the new stripes lay on top of the old stripes, unless you move >> the data offset. Which is why a backup file holds the old stripe just >> in case. If you can move the offset, you use the lower offset for the >> lower addresses in the array, and the higher offset for the higher >> addresses, on either side of the reshape position. > > Okay, understood. So v0.9 and v1.0 always need a backup for a reshape. > > But if we have a data offset with v1.2, a reshape will use that space if > it can rather than needing a backup file? If there's room to move the entire data area (direction varies with operation), yes. > (And changing topic slightly, that space is also used for an internal > bitmap?) And bad block log. Phil