FYI, as a regression from SL6.0 and SL6.1, SL6.2 does not boot from degraded RAID1 devices.

If your "/" is on a RAID1 mirrored across 2 disks and 1 of the 2 disks dies, your system will
not boot because dracut does not activate the required md devices.

This is a very serious problem because RAID1 (mirroring) of "/" and "swap" is a popular
solution for protecting against single-disk failures. The present bug defeats this protection
and makes the situation worse because failure of either of the 2 disks makes your system
unbootable.

It is astonishing that this problem was not caught by anybody's QA, did not receive
wide publicity *and* the solution was not pushed into the current release of SL.

Bug report against dracut was filed in January:
https://bugzilla.redhat.com/show_bug.cgi?id=772926
marked as duplicate of secret bug:
https://bugzilla.redhat.com/show_bug.cgi?id=761584
solution made available in July for (the best I can tell) the 6.3 release:
http://rhn.redhat.com/errata/RHBA-2012-0839.html (dracut-004-283.el6.src.rpm)
http://rhn.redhat.com/errata/RHBA-2012-1078.html (dracut-004-284.el6_3.src.rpm)

These RPMs are available in SL6 .../6rolling/x86_64/updates/fastbugs/

I confirm that dracut-004-284.el6_3 can boot SL6.2 from degraded "/" (one disk missing).

Note that applying the fix on affected systems is not trivial:

1) rpm -vh --upgrade dracut-004-284.el6_3.noarch.rpm dracut-kernel-004-284.el6_3.noarch.rpm
2) bad dracut is still present inside the /boot/initramfs files, your system is still broken
3) dracut -v -f ### this rebuilds the initramfs for the ***presently running*** kernel, not necessarily the one used for the next reboot
4) find /boot -name 'initramfs*.img' -print -exec lsinitrd {} \; | grep dracut-0 ### report dracut version inside all /boot/initramfs files
5) dracut -v -f /boot/initramfs-2.6.32-279.1.1.el6.x86_64.img 2.6.32-279.1.1.el6.x86_64 ### rebuild initramfs for the latest update kernel


Good luck!
K.O.



On Thu, Jul 19, 2012 at 03:07:19PM -0500, Connie Sieh wrote:
> On Thu, 19 Jul 2012, Sean wrote:
> 
> >Hi
> >
> >With reference to : http://rhn.redhat.com/errata/RHBA-2012-0839.html
> >
> >I have a bunch of new servers which we bought with dual internal disks
> >for raid1, these are effectively unusable until this update
> >is pushed through to SL ?
> >
> >Is there a reason for it not making it from redhat into sl6 x86_64?
> >
> >I have looked everywhere but can only find dracut 004-256.
> >and not 004-283.
> 
> 004-283 was a fastbug for RHEL 6.3 .  Since we have not released SL
> 6.3 yet it is only available in the 6rolling tree.
> 
> ftp://ftp.scientificlinux.org/linux/scientific/6rolling/x86_64/updates/fastbugs/
> 
> -Connie Sieh
> 
> >
> >
> >Thanks
> >Sean
> >

-- 
Konstantin Olchanski
Data Acquisition Systems: The Bytes Must Flow!
Email: olchansk-at-triumf-dot-ca
Snail mail: 4004 Wesbrook Mall, TRIUMF, Vancouver, B.C., V6T 2A3, Canada