[CentOS] preferred software RAID 10?

Ross S. W. Walker RWalker at medallion.com
Wed Jun 25 18:30:39 UTC 2008

Rudi Ahlers wrote:

> Ross S. W. Walker wrote:
> > Rudi Ahlers wrote:
> >   
> >> Hi all
> >>
> >> I'm looking at setting up software RAID 10, using CentOS 5.1 x64 - what 
> >> is the best way todo this?
> >>
> >> I'm reading some sources on the internet, and get a lot of different 
> >> "suggestions"
> >>
> >> 1 suggestion says to boot up with a Live CD like Knoppix or 
> >> SystemRescueCD, setup the RAID 10 partitions, and then install Linux 
> >> from there.
> >> 2. Another is to setup a small RAID 1 on the first 2 HDD's, install 
> >> Linux, bootup, and then setup the rest as RAID 10
> >>
> >> The others didn't really make sense to me, so how do I 
> >> actually do this?
> >>
> >> 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?
> >>     
> >
> > What's the hardware setup?
> >
> I didn't really specify any, cause I want to keep it purely software. 
> Generally it would be on a generic PIV motherboard with 4 / 6 
> SATA, or even mixed SATA & IDE HDD's - all new, so at least 80GB per HDD

I was primarily interested in the # of HDDs that can be used.

If you have 6 disks, setup 2 disks as a  RAID1 for the OS and the
other 4 as a RAID10 for the data.

If you have 4 disks all together:

1) create /boot partition as a 4 disk RAID1 across all 4 disks

2) create the remaining space as 2 separate RAID1s of type LVM

3) create a VG out of the 2 RAID1 PVs, create root, swap LVs on
the VG with a stripe of 2.

LVM striping over multiple RAID1 PVs provides the same performance
as a native RAID10 array, plus you can add RAID1s later to
increase the size/performance and dump/restore the data to stripe
it across the larger set of PVs.


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