Re: preferred software RAID 10?

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Ross S. W. Walker wrote:
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.

-Ross

_____________________________________________________________________
Thanx, this seems like a fairly easy way of doing it.

From what I gather, the data will fill up from the beginning of the stripe, right? So the 1st 2 HDD's will work hardest in the beginning, until there's enough data to fill the other 2 HDD's - unless of cause I split the LV's across the PV's - i.e. put root on md1 & swap or var on md2 for example.

Does swap need to be part of the RAID set? Is there actually a performance boost?

--

Kind Regards
Rudi Ahlers

Check out my technical blog, http://blog.softdux.com for Linux or other technical stuff


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