From mboxrd@z Thu Jan 1 00:00:00 1970 From: Doug Ledford Date: Tue, 14 Jul 2009 14:14:35 +0000 Subject: Re: RFC: mdadm and bringing up raid sets from initrd (dracut) Message-Id: MIME-Version: 1 Content-Type: multipart/mixed; boundary="Apple-Mail-89-838219897" List-Id: References: <4A5C6501.3080607@redhat.com> <1955210A-EF27-479F-8C58-BA4FA9018A56@redhat.com> <4A5C9E17.2060106@redhat.com> In-Reply-To: <4A5C9E17.2060106@redhat.com> To: Hans de Goede Cc: initramfs , linux-hotplug@vger.kernel.org, "Danecki, Jacek" , Harald Hoyer This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --Apple-Mail-89-838219897 Content-Type: text/plain; charset=US-ASCII; format=flowed; delsp=yes Content-Transfer-Encoding: 7bit On Jul 14, 2009, at 11:02 AM, Hans de Goede wrote: > Hi, > On 07/14/2009 03:39 PM, Doug Ledford wrote: >> On Jul 14, 2009, at 6:59 AM, Hans de Goede wrote: >>> Hi, >>> >>> As you probably know I'm working on making Fedora 12 use mdraid >>> instead of dmraid for Intel BIOS-RAID setups. >>> >>> The installer (anaconda) part is mostly done (needs more testing) >>> and now I'm looking at implementing support for this in dracut >>> (the new mkinitrd for Fedora 12). >>> >>> So I've been testing how this works for both imsm mdraid sets >>> and native mdraid metadata sets, in both cases using a 2 disk >>> mirror, so that the set can also be brought up in degraded mode. >>> >>> Currently the udev rules use incremental assembly like this: >>> mdadm -I /dev/mdraid-member >> >> Hmmm...does dracut use udev during initramfs time? > > Yes, it uses udev for everything, making discovery of / consistent > with the discovery of other storage devices. I'm not sure I like or agree with that philosophy. I absolutely *don't* want my / filesystem or raid device treated like some plug in, temporary, roaming raid device. They *aren't* the same, not in terms of importance to the running of the machine and not in terms of reliability requirements. By using mdadm -A in the mkinitrd calls, I was able to put in an mdadm.conf file and limit what arrays get started to arrays found non-ambiguously in that mdadm.conf file and identified by UUID. When you switch to incremental assembly for root, you risk the possibility of name space collisions and non- deterministic bring up of your / array. > > >> Are we going to be totally changing this with >> dracut and F12? This method very nicely resolves the issues you >> posted. >> > > Yes. > > Regards, > > Hans -- Doug Ledford GPG KeyID: CFBFF194 http://people.redhat.com/dledford InfiniBand Specific RPMS http://people.redhat.com/dledford/Infiniband --Apple-Mail-89-838219897 content-type: application/pgp-signature; x-mac-type=70674453; name=PGP.sig content-description: This is a digitally signed message part content-disposition: inline; filename=PGP.sig content-transfer-encoding: 7bit -----BEGIN PGP SIGNATURE----- Version: GnuPG/MacGPG2 v2.0.11 (Darwin) iEYEARECAAYFAkpckssACgkQQ9aEs6Ims9i7bACghKl1/eFD6Bx7nYX+e9SUN0bK ICsAn2c8mwOHmPf7Wl91ZtOvk25HU1+A =X2Wn -----END PGP SIGNATURE----- --Apple-Mail-89-838219897--