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| Peanut | Hi folks - is there a way that I could use the busybox shell in the Ubuntu installer environment to put an MBR on a disk? I've got a failed disk in a mirror pair, and it turns out that the second half of the mirror isn't bootable although it (presumably) holds a good copy of all the data. | 14:05 |
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| cjwatson | Peanut: you can do it with parted ('anna-install parted-udeb' if it isn't already there) | 14:08 |
| Peanut | cjwatson: ah, neat - I'll try that. | 14:09 |
| Peanut | Ah, parted is a different udeb than partman (tried it with partman, but that didn't quite want to do what I wanted it to do). | 14:15 |
| cjwatson | parted is a command-line UI to libparted, which partman uses | 14:16 |
| cjwatson | I suggest setting its units to sectors so that it doesn't try to get too clever | 14:17 |
| cjwatson | kpartx (kpartx-udeb) might help too | 14:18 |
| cjwatson | Actually, given your problem description, it's possible you'd be best off using sfdisk (fdisk-udeb) to dump the partition table from the first disk and restore it onto the second | 14:19 |
| cjwatson | sfdisk -d working-disk-device >sfdisk-out; READ THE OUTPUT FILE VERY CAREFULLY; sfdisk broken-disk-device <sfdisk-out | 14:20 |
| Peanut | cjwatson: thanks, thanks, I was just finding out that parted doesn't have an easy way to copy partitions from one drive to the other. | 14:21 |
| Peanut | And I've used cfdisk in the past when I had a prompt, but didn't know I could anna-install it in the network boot environment. | 14:22 |
| cjwatson | Might need to modify partition references in that file | 14:24 |
| xnox | also backup the broken disk, in it's current state. | 14:32 |
| xnox | just in case. | 14:32 |
| xnox | (partition table at least) | 14:32 |
| Peanut | Meh.. I copied over the partition table, then synched the mirrors.. but it just goes in a reboot loop when trying to boot from disk. | 14:41 |
| Peanut | Oh.. and I did a 'grub-install' as /etc/default/grub knows about both mirrors. | 14:41 |
| cjwatson | 15:19 <cjwatson> Actually, given your problem description, it's possible you'd be best off using sfdisk (fdisk-udeb) to dump the partition table from the first disk and restore it onto the second | 14:42 |
| cjwatson | 15:20 <cjwatson> sfdisk -d working-disk-device >sfdisk-out; READ THE OUTPUT FILE VERY CAREFULLY; sfdisk broken-disk-device <sfdisk-out | 14:42 |
| cjwatson | 15:21 <cjwatson> Might need to modify partition references in that file | 14:42 |
| cjwatson | Sorry, bad timing on disconnect | 14:42 |
| Peanut | Ah ok - I did read those things you said :-) | 14:43 |
| Peanut | What's the correct syntax to make grub-installer put GRUB on the MBR of /dev/sda ? | 14:55 |
| cjwatson | grub-installer or grub-install? (they're different) | 14:56 |
| Peanut | The one from the boot environment - grub-installer | 14:56 |
| cjwatson | You don't want to use that ... | 14:57 |
| cjwatson | Not unless you're doing an install from scratch and using it as part of the menu-driven interface | 14:57 |
| Peanut | Ah ok, I'm not. I've used dd to verify that there's no grub on the bootsector of /dev/sda | 14:58 |
| cjwatson | Boot into rescue mode instead and use the "Reinstall GRUB boot loader" option | 14:58 |
| cjwatson | "Rescue a broken system" from the CD boot menu | 14:58 |
| Peanut | cjwatson: ah ok.. these machines have no CDrom, but I have a netboot d-i setup that I'm booting them into, without giving them a preseed file (that'd be a full re-install). | 14:59 |
| cjwatson | rescue/enable=true as a boot param, then | 15:02 |
| Peanut | Ah, that's how you get to that.. thanks. | 15:03 |
| * Peanut is getting very tempted to just copy the first 466 bytes from /dev/sdb onto /dev/sda though ;-) | 15:04 | |
| Peanut | Because any attempt at running in-target grub-install fails as well, due to the chroot environment. So having that in all my late_run.sh turns out to have been quite useless. | 15:05 |
| cjwatson | Err, GRUB doesn't reside in just the first 466 bytes | 15:07 |
| cjwatson | Copying that is likely a very bad idea since sometimes there's a signature | 15:07 |
| cjwatson | (as in a disk ID, not a crypto sig) | 15:07 |
| Peanut | cjwatson: ah, ok. Both disks should now have identical contents within their partitions, and identical partition tables, so only the stage 1 of grub is missing. I'll try the rescue/enable=true. | 15:10 |
| cjwatson | A bit more than that actually (stage 1 is a GRUB Legacy concept, although it's roughly equivalent to boot.img in GRUB 2; https://www.gnu.org/software/grub/manual/grub.html#Images). I expect you will be missing the core image too. | 15:12 |
| cjwatson | Since in the MBR layout that does not reside within a partition. | 15:12 |
| Peanut | This is a lucid64 system (grub 1.98) that I'm trying to fix. | 15:14 |
| cjwatson | GRUB 1.98 is GRUB 2. | 15:14 |
| cjwatson | GRUB Legacy got up to 0.97. | 15:14 |
| cjwatson | More accurately, I should say that GRUB 1.98 is from the GRUB 2 series. | 15:15 |
| cjwatson | For this purpose the URL above is accurate for 1.98. | 15:15 |
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| Peanut | cjwatson: thanks for all the help, I got all my nodes back up and running again. | 18:09 |
| cjwatson | Great | 18:52 |
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