--On Saturday, August 13, 2011 08:59:30 AM -0400 William Warren
> On 8/13/2011 7:40 AM, B.J. McClure wrote:
>> boot partition must be raid 1. Grub does not work with 5, 10. etc.
> found out grub will not boot directly off the /boot md device..but i can
> make grub put itself on the mbr's of both disks..
Both steps are necessary for a properly redundant configuration.
Depending on the age/interface/BIOS of your machine, if you lose your
primary/master hard disk you may have to switch cabling to make
your other disk (containing the mirror of /boot) the primary/master.
Many modern BIOSes will allow you to select the boot priority order
between disks without moving cables.
This is something that is best determined empirically before you
put your machine into production ...
Typically, I do the following:
1. Put /boot onto a mirrored md device based on 200MB partitions.
2. Put the remaining disk space into a second partition using
whatever RAID level is appropriate (including 5 or 6)
3. Give the large raid device to LVM
4. Add LVM-based filesystems as necessary.
5. After the system is fully installed, ensure that all boot
drives have a copy of the proper MBR.
6. Test by powering down, removing the original boot drive,
and powering up again (after ensuring that all RAID sync
operations have been completed).
This has worked fine for quite a while (CentOS 5.x) and I can
verify that RAID1 (/boot) + RAID6 (remainder) work just fine
with CentOS 6, including putting an encryption layer between
the RAID6 device and LVM.
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