[CentOS] CentOS 6.2 software raid 10 with LVM - Need help with degraded drive and only one MBR

Ross Walker rswwalker at gmail.com
Mon Mar 5 18:12:52 EST 2012


On Mar 4, 2012, at 8:01 PM, "Luke S. Crawford" <lsc at prgmr.com> wrote:

>> Right.  I was referring to RAID 1.  For a RAID 10, you would have to
>> find the proper drive to boot from.  This is why I tend to limit myself
>> to RAID 1 in software.  If I need something more complex than that, I
>> get a hardware card so the OS just sees it as a single drive and you
>> don't have to worry about grub.
> 
> When I want to boot off of a raid 10, I first partition the drives
> and make a small (like a gigabyte) partition 1, and put the rest of 
> the space on partition 2.  I do this on all drives, then I create
> a raid 1 of sd[abcd]1 for /, and a raid10 of sd[abcd]2 for everything 
> else.   I've got this config on several tens of servers and it seems
> to work okay.  

Technically if the data portion is a true RAID10 you would only need to mirror /boot to sdb, cause if both sda AND sdb are out then the whole RAID10 is SOL and there would be no need to boot off of sdc or sdd.

Having said that though it's just easier to create a 4 disk raid1 of /boot and duplicate the MBR across all of them.

That should be standard practice for ALL software RAID setups as it allows initial boot from any device in the set. Then with the data portion of the drive it can be RAID10, RAID5 etc.

Sounds like the hosting provider isn't very Linux savvy. I would always double check the setup of any system someone else installs for you.

-Ross



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