From mboxrd@z Thu Jan 1 00:00:00 1970 From: Neil Brown Subject: Re: Autostarting arrays with V1 metadata Date: Thu, 8 May 2008 13:05:44 +1000 Message-ID: <18466.28168.343215.443749@notabene.brown> References: <4821EEFB.1040501@bluecherry.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: message from Ben Winslow on Wednesday May 7 Sender: linux-raid-owner@vger.kernel.org To: Ben Winslow Cc: linux-raid@vger.kernel.org List-Id: linux-raid.ids On Wednesday May 7, rain@bluecherry.net wrote: > I've noticed that (as of 2.6.25, at least) the kernel doesn't autostart > arrays with V1 metadata. In autostart_arrays(), md_import_device() is > called for 0.90 arrays only, and there's currently no sort of > autodetection of the superblock position for V1 metadata. > > Is this simply a matter of the code being unwritten, or are there other > reasons that V1 arrays aren't autostarted (such as the SB format being > unfinished)? My only real motivation to use V1 metadata is the unhashed > homehost field, which I'll give up if the SB format hasn't stabilized yet. V1.x metadata (deliberately) doesn't contain sufficient information to allow in-kernel autodetect. In particular it doesn't store the 'minor number' information so the kernel wouldn't know which md device to use. However it is quite possible to assemble V1.x arrays using mdadm in an initrd. This is the preferred method. Ofcourse, if the array doesn't hold the root filesystem, you can just assemble it as part of the regular boot scripts. NeilBrown