I'm a bit of a Linux noob, feel free to redirect me elsewhere if this is an inappropriate post for this list - also, apologies for the many questions. I've got a set of arrays that I boot up using Ubuntu (latest MM) and a couple of Live CD distros for doing maintanence, particularly System Rescue (gentoo) and Grml (debian), as well as the regular production server OS, which is rpath-based, pretty close to "stable" (read: ancient) rhel. When one of the RAID1 arrays kept dropping all but two of the members, I re-created it with options "-e=0.90 --auto=md". This was the boot array for Ubuntu, which failed at boot time due to its UUID changing. I figured the best thing to do would be to simply set the array's UUID back to what it was before, so I ran e2fstune to do so, but unfortunately I got it wrong (UUIDs are so human-unfriendly!), so now it seems I'm doubly hosed, but I'm taking it on as a learning experience 8-) When I ran update-initramfs I got an extended message, apparently from mdadm, about making sure that my UUIDs were consistent between mdadm.conf and fstab. Well my fstab is based on filesystem labels (so much better!), so I thought no worries, but when I ran the suggested script - /usr/share/mdadm/mkconf, that returned a UUID for the array that is completely different from that shown by blkid! So, first the simple questions: Q1 between mkconf and blkid, which should I trust for the current UUID of the array (both the filesystem and the underlying component partitions are the same right?) Q2 I've noticed that fail/removing a component doesn't always re-set the UUID, even when --zero-superblock'ing I sometimes need to actually re-format the partition or use e2fstune to reset the UUID manually, but other times no problems. Is this a version-specific difference? Q3 Can I take the UUIDs out of my mdadmconf and just use the super-minor? I'd really like to use the filesystem label, but that doesn't seem to be an option. The more complex question (I realize it's OT for the list so feel free to ignore) Q4 Besides the following, are there other places need to be changed when the UUID changes? bootloader kernel statements fstab mdadm.conf update-initramfs grub2 is handling my booting from a dedicated partition where I manually maintain the grub.conf, so I'm using filesystem labels there as well, but I'm thinking I'll also have to re-run grub-install and grub-mkconfig to rebuild the boot-sector images and get a new intra-partition grub.conf for Ubuntu? I'm chaining from my manually maintained "uber grub.cfg" into Ubuntu's automatically-maintained grub.cfg via configfile. Finally, a big-picture question: Q5 I've noticed that my arrays aren't quite as as stable as I'd like, and I'm wondering if that might be due to the different flavors/versions of mdadm running? The kernels range from 24 to 35, and while I'm using .0.90.3 metadata for the boot arrays, I've gone with 1.2 for the big storage RAID6's. Thanks in advance. . . -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
