software raid

[David A. Bandel]

On Thu, Aug 7, 2008 at 5:09 PM, James McDonald
<james at jamesmcdonald.id.au> wrote:
> C M Reinehr wrote:
>>
>> Glad you could figure it out.
>>
>> I'm just the opposite, I prefer the software (md) raid and use nothing but
>> Raid 1. Considering how inexpensive hard drive capacity is these days, I
>> don't mind the extra expense of raid 1 over raid 5. I overlay the raid
>> drives with LVM and get stripping, as well. I like the fact that if a drive
>> fails I still can recover the data off of the remaining drive.
>>
>> cmr
>>
>>
>
> A question. The /boot partition needs to be on a non-raid volume or how does
> that work?
>

No.  /boot only needs a different partition if you have an encrypted
LVM (like my laptops).  All my servers (over a dozen) are software
RAIDed and boot from the RAID partition using LILO (don't know if GRUB
can do this or not).  The initrd.img must have the appropriate md
drivers and mdadm code is all (and the paritions marked as fd, not
83), but that is handled on Debian systems and I would assume most
others as well.

/etc/lilo.conf extract (when booting from mbr):

boot=/dev/md0  # my /boot directory
root=/dev/md1  # my / directory
raid-extra-boot=mbr-only  # needed for mbr booting

You will get warnings about sdb not being the first drive, but lilo
must write both mbr's to ensure you can boot from the second drive if
the first one fails (in which case sdb would become sda after breaking
the mirror).  You would get more errors w/ RAID 5, but same goes as
before -- you need to write all mbr's just in case).

Ciao,

David A. Bandel
-- 
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 - Nemesis Air Racing Team motto