[CentOS] C7: How to configure raid at install time

Wed Nov 25 17:43:57 UTC 2015
Gordon Messmer <gordon.messmer at gmail.com>

On 11/25/2015 09:09 AM, Fred Smith wrote:
> should I put swap on both drives? should it be RAID1 also, or just
> two swap partitions not in any RAID volume?

I really recommend using the fewest partitions possible, since md RAID 
operates on partitions (Anaconda won't create full disk md RAID 
volumes), and replacing a disk will require you to handle each partition 
individually.  It's probably best to do a small /boot on RAID1 and use 
the rest of the disk for a second RAID1 volume, with LVM on that.

(If you haven't looked at the links I posted earlier, do consider that)

> (I remember seeing a somewhat technical article in the last couple
> of  years that talked of a potential corruption issue if one puts
> swap into a  Linux software RAID-1 volume, but no longer recall
> the details.)

There's no corruption.  If a write is canceled before it completes, you 
might end up with a block mis-match (or might have, I'm not sure if that 
still happens), but no corruption.  The mis-match is on a block that 
isn't mapped to anything, and will never be read by anything other than 
a RAID verify.  It's ugly because it means the verify operation is no 
longer useful, but it won't cause any read from the RAID volume to 
return bad data.