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Florian D. posted <433FDF0A.4090306@×××.at>, excerpted below, on Sun, 02 |
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Oct 2005 15:22:18 +0200: |
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> i cannot understand, how you got things working without an extra /boot |
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> partition. the system needs initrd to start the LVM, right? but if |
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> initrd itself is on the LVM...? very interesting ;-) |
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He didn't say he didn't have an extra boot. He only enumerated the LVs |
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(logical volumes) on the MD/RAID, which he said was on sda5, sdb5, etc, |
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all partition 5, on /dev/md5. |
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The usual way to handle that, if you are booting from the RAID array |
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as well, is to create a small raid1 array out of small partitions toward |
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the front of each physical disk, for /boot. Being raid1 (mirrored), the |
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same data is imaged to all disks in the raid1 identically. Both GRUB and |
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LILO can read individual disk partitions belonging to the mirror array as |
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if they were stand-alone partitions, so can boot from any of them, altho |
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they do boot from only one at a time. The kernel and initrd are on this |
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boot array (so mirrored to each physical disk in the array), and can then |
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be loaded. Root and other LVs are then created on the main VG (volume |
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group (or multiple groups) taking the rest of the disks, to be loaded from |
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the initrd. Once /they/ are loaded, and the pivot_root to the main-root |
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on the main VG is accomplished, the raid1 array containing /boot can be |
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mounted, if desired. (As usual, Gentoo keeps /boot unmounted by default.) |
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|
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... As some may guess, I've been studying this stuff recently! =8^) I |
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don't have my own RAID setup yet, but probably will by late this week. (I |
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plan to go pickup the drives probably Tue or Wed.) |
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Of course, he didn't actually say /boot is on raid1, either. It may be on |
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a conventional disk, perhaps manually backed up. There is some clue that |
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there are extra partitions, however, and probably extra RAID volumes as |
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well, since both the partitions and the md's mentioned were #5. Now, #5 |
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is the first secondary partition in the extended partition, so there |
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wouldn't /have/ to be a 1-4. However, there's likely at least an sdX1 on |
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all the disks, which would form the raid1 for /boot. |
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-- |
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Duncan - List replies preferred. No HTML msgs. |
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"Every nonfree program has a lord, a master -- |
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and if you use the program, he is your master." Richard Stallman in |
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http://www.linuxdevcenter.com/pub/a/linux/2004/12/22/rms_interview.html |
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-- |
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