[CentOS-docs] Updated How to Setup a Software RAID on CentOS 5

Wed Apr 29 18:36:27 UTC 2009
Phil Schaffner <Philip.R.Schaffner at NASA.gov>

Ned Slider wrote:
> I can't think of a good argument for not having /boot on the raid1. 
> Presumably performance isn't an issue as the contents of /boot gets read 
> once at system boot (other than maybe fast booting performance, but 
> that's not really going to be an issue for a server running raid1, right?)


> SWAP on raid0 is a bad idea as one drive failure may cause the system to 
> fail to boot. I guess SWAP on raid1 is the safe option. If SWAP 
> performance is critical, then maybe two independent non-raid partitions, 
> one at the start of each drive, and set to the same priority would be a 
> better solution (effectively giving stripped raid0 performance). 
> Presumably then a drive failure wouldn't prevent booting but would 
> result in a warning that one of the SWAPs was unavailable (assuming the 
> system could function fine with the size of the remaining SWAP)?
> Hopefully someone can verify my logic here.

Sounds right to me.  Will test that on VMware as part of my tests of the 
procedure and report back if we are wrong.


> If grub is present on the mbr of both drives, then the system will 
> remain functional if *either* drive fails without any further 
> intervention. I would think this is the ideal.

That is the theory.

> I would be in favour of extending the current page to include 
> testing/recovery information in the event of a drive failure. If the 
> information is not specific to only raid1, then maybe a separate page is 
> warranted.

That sounds like a more general topic to me - not ready to add it to 
this page, but if anyone (with edit rights) wants to, feel free.