From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michael Evans Subject: Re: Linux mdadm superblock question. Date: Sun, 14 Feb 2010 00:38:58 -0800 Message-ID: <4877c76c1002140038p4a7d8d75r3bc9d615b0e68199@mail.gmail.com> References: <201002140251.59668.volkerarmin@googlemail.com> <4877c76c1002132002s20d942c3i7cee5418cdcf369c@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org To: david@lang.hm Cc: Volker Armin Hemmann , linux-kernel@vger.kernel.org, linux-raid@vger.kernel.org List-Id: linux-raid.ids On Sat, Feb 13, 2010 at 11:21 PM, wrote: > On Sat, 13 Feb 2010, Michael Evans wrote: > >> On Sat, Feb 13, 2010 at 5:51 PM, Volker Armin Hemmann >> wrote: >>>> >>>> 0.90 has a very bad problem, which is that it is hard to distingui= sh >>>> between a RAID partition at the end of volume and a full RAID devi= ce. >>>> This is because 0.90 doesn't actually tell you the start of the de= vice. >>>> >>>> Then, of course, there are a lot of limitations on size, number of >>>> devices, and so on in 0.90. >>> >>> but it is the only format supporting autodetection. >>> >>> So - when will autodetection be introduced with 1.X? And if not, wh= y not? >>> >>> All I found was 'autodetection might be troublesome' and nothing el= se. >>> =A0But dealing with initrds is troublesome too. Pure evil even. >>> >>> Gl?ck Auf, >>> Volker >>> -- >>> To unsubscribe from this list: send the line "unsubscribe linux-rai= d" in >>> the body of a message to majordomo@vger.kernel.org >>> More majordomo info at =A0http://vger.kernel.org/majordomo-info.htm= l >>> >> >> I remember hearing that 1.x had /no/ plans for kernel level >> auto-detection ever. =A0That can be accomplished in early-userspace >> leaving the code in the kernel much less complex, and therefore far >> more reliable. >> >> In other words, 'auto-detection' for 1.x format devices is using an >> initrd/initramfs. > > hmm, I've used 1.x formats without an initrd/initramfs (and without a= ny > conifg file on the server) and have had no problem with them being > discovered. I haven't tried to use one for a boot/root device, so tha= t may > be the difference. > > David Lang Yes, that is the difference. You must have a more traditional simple block device and filesystem drivers compiled in. You have no need for extra drivers or higher level device detection and evaluation (with user-set policies to determine operation). Anything past root-fs mount can happen in normal user-space before logins are enabled.