[CentOS] preferred software RAID 10?

Ross S. W. Walker RWalker at medallion.com
Thu Jul 17 22:39:57 UTC 2008

Rudi Ahlers wrote:
> John R Pierce wrote:
> > Rudi Ahlers wrote:
> >> And then, how do I setup the partitioning? Do I setup /boot on a 
> >> separate RAID "partition"? If so, what happens if I want to replace 
> >> the 1st 2 HDD's with bigger ones?
> >
> >
> > each partition is raided seperately with mdadm.... you could make the 
> > whole thing one LVM partition thats raid10, then use LVM to dice it up 
> > into file systems.
> >
> > if you have 4 drives and are doing software raid10, you won't be 
> > swapping drives with different sizes without a WHOLE lotta pain.
> Ok, so how do I do this? Let's say I have 4x 160GB HDD's now, and plan 
> on replacing them with 4x 500GB HDD's in the future?

Personally I would never put an OS install on a higher RAID then RAID1,
because it gets too messy to upgrade like you suggested.

> What setup would help with a upgrade in the future?
> >
> > /boot shouldn't be mirrored, as the BIOS won't know how to boot it. 
> > leave /dev/sdb1 the same size as /dev/sda1 and call it /boot2 and try 
> > to remember to copy /boot to /boot2 each time you update the kernel.
> I understand this, but how do you boot from /boot2 on the 
> second HDD if the 1st have failed?

Could you not get a system that had 2 drives for the OS and 4 drives
for data?

I have setup 4 disk RAID10 systems before, but they were never
intended to be upgraded (in place at least).

I can forward a couple of recipes, but let me first say that to do
it from the CentOS install media requires 2 RAID1s and LVM striping
because the RAID10 option isn't on the media, but it is functionally
equivalent both in useable space and performance.

If you want to use the MD RAID10 driver you need to build it from a
working system then install on it.


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