[CentOS] LVM & Softraid & expansion

[Roy Ong]

On Sat, 2007-03-31 at 22:14 -0700, John R Pierce wrote:
> Cen Tos wrote:
> > I've been reading the RHEL 5 manual/guide linked from centos, and the 
> > idea of LVM with expandable partitions seems like a great idea (yes 
> > duh why else would it exist if not?). Although the documentation shows 
> > a screenshot of how the final setup would look like with LVM & RAID 
> > together, it doesn't actually gives the step.
> >
> > 1. Am I correct in thinking it should be done in this way
> > - setup Softraid
> > - setup LVM on the raid partitions
> >
> >
> > Secondly, LVM allows expansion of the LVM group when we add a new 
> > drive. But with softraid, how will this happen? Searching around does 
> > not turn up any guide on this. Am I correct in thinking I must always 
> > add new drives in pairs (for Raid 1), create a new softraid partition 
> > then assign this new partition to the LVM group?
> 
> yup, pretty much thats how it works.
> 
> In IBM AIX (where LVM kinda came from), the soft raid and volume 
> management is rather tightly integrated, but in linux, its seperate.

I guess you've got the gist of the matter right
- setup software raid
- setup LVM on the software raid paritions

and if you need to increase space thereafter
- add in the physical drives
- setup new software raid
- add these /dev/mdX into LVM (pvcreate, vgextend etc.)