Thank you for your answer Neil. I assumed that an update to the superblock checksumming routine was the reason though I didn't find very much information about this update and potential consequences on older systems. But, above all, I am very surprised that the new mdadm does not even warn the user about potential raid corruption when used on an old one.
As you suggested, I tried recreating the array using option --assume-clean. So, I booted a Sarge cdrom, checked that chunksize and layout was default ones then I typed: $ mdadm --create /dev/md0 --level=raid5 --raid-devices=3 --auto=yes --assume-clean /dev/sda2 /dev/sdb2 /dev/sdc2 And that worked! recreating the array without loss of data: I ran fsck on /dev/md0, no error were reported, then mounted it to check that all data was there; no pb. Then, I rebooted the server and... GOT A KERNEL PANIC AGAIN... this time for: invalid uuid ! I patiently rebooted the Sarge cdrom again and tried to reassemble the raid updating the uuid (which I fortunately backed up), using: $ mdadm --assemble /dev/md0 --auto=yes --uuid=#old#:#uuid#:#back#:#up# --update=uuid /dev/sda2 /dev/sdb2 /dev/sdc2 Then, I got an error from mdadm saying that option "uuid" for --update was not valid! Only "sparc2.2", "summaries" and "resync" seams supported on that version of mdadm (1.9.0). Now, I don't know what to do and would be grateful for any suggestion to make my system boot again. Thanks by advance for your help, Regards > -----Message d'origine----- > De : Neil Brown [mailto:ne...@suse.de] > Envoyé : vendredi 26 juin 2009 03:56 > À : RUSSOTTO François-Xavier 200103; 534...@bugs.debian.org > Objet : Re: Bug#534470: Using mdadm 2.6.7.2 to assemble a raid array > created withmdadm 1.9.0 will corrupt it making mdadm 1.9.0 to crash > whentrying to reassemble > > On Wednesday June 24, francois-xavier.russo...@cea.fr wrote: > > Package: mdadm > > Version: 2.6.7.2 > > Severity: critical > > > > After booting a Debian 5.0.1 - Lenny install cdrom in rescue mode > > (debian-501-ia64-netinst.iso) on an Itanium 2 server with Debian 3.1 > > - Sarge (ia64) installed on a software raid 5 root partition, > > opening a console in the root partition mounted from the raid array > > (auto-assembled) corrupts the raid array, leading to a kernel panic > > at server reboot, and preventing from manual reassembly using mdadm > > 1.9.0 (Sarge). > > > > The raid 5 array containing the root partition is made of 3 > > partitions on 3 scsi disks (sda2, sdb2, sdc2) which ran fluently for > > years. Here is the output at server reboot: > > > > md: invalid superblock checksum on sdb2 > .... > > > > Apart from fixing this bug, I would be grateful that you suggest me > > a safe way to make the server bootable again. I was thinking about > > booting on a Sarge install cdrom and try to re-create the raid array > > with option "--assume-clean" or, if that fails, re-create the array > > and restore content from a tar backup. > > This problem is due to the fact that the superblock checksumming > routine was changed since 2.6.8. > It was changed because it used code that was different on different > architectures, and was basically unmaintainable. > New kernels can accept most old checksums, but old kernels cannot > necessarily accept the new ones, and mdadm does not know enough about > kernel internals to always create the correct old one. > > So it isn't really fixable. > > If you boot with the Sarge install cdrom and reacreate the array with > --assume-clean as you suggest it should work fine. > Check the "--examine" values for chunksize and layout, and the order > of the drives, and make sure you preserve all of those. > > NeilBrown -- To UNSUBSCRIBE, email to debian-bugs-rc-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org
