[CentOS] preferred software RAID 10?

Rudi Ahlers Rudi at SoftDux.com
Thu Jul 17 22:46:07 UTC 2008

Ross S. W. Walker wrote:
> 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.
So you're suggesting that I keep the OS separate from the data? But what 
happens if both the 1st 2 drives with the OS fails, or needs to be replaced?
>> 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?
nope, unfortunately not. It's a 2U rackmount chassis with space for only 
4 HDD's. I have been thinking about installing the OS onto a USB memory 
stick, but have never actually got as far as trying to figure out how 
todo it.
> 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.
Please share your recipes, I'd like to give it a try  :)


Kind Regards
Rudi Ahlers

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