[CentOS] Advice on setting up Raid and LVM

[Bowie Bailey]

Matt Hyclak wrote:
> On Thu, Mar 02, 2006, Fajar Priyanto enlightened us: 
> > I'm setting up Centos4.2 on 2x80GB SATA drives.
> > 
> > The partition scheme is like this:
> > /boot = 300MB
> > / = 9.2GB
> > /home = 70GB
> > swap = 500MB
> > 
> > 
> > The RAID is RAID 1.
> > md0 = 300MB = /boot
> > md1 = 9.2GB = LVM
> > md2 = 70GB = LVM
> > md3 = 500MB = LVM
> > 
> > Now, the confusing part is:
> > 1. When creating VolGroup00, should I include all PV (md1, md2,
> > md3)? Then create the LV. 
> > 2. When setting up RAID 1, should I make those separated partitions
> > for /, /home, and swap? Or, should I just make one big RAID device?
> > 
> > The future purpose of using LVM is I want to be able to expand any
> > partitions that would run out of space into a new disk.
> 
> Personally, I would do:
> 
> md0 = 300MB (/boot)
> md1 = 500MB (swap)
> md2 = remainder (pv.00)
> 
> I would then create a single volume group on md2, create / and home,
> but I would leave 20-30% of the VG empty so you can expand later.
> That would work out to like 10GB /, and 50GB /home, and leave you 15
> or so GB for expansion. 

Or you could do this:

RAID 1 partition:
md0 = 80GB (or whatever the useable total is)

Then include md0 in VolGroup00 and create your logical volumes.

LV0 = 300MB (/boot)
LV1 = 500MB (swap)
LV2 = 9.2GB (/)
LV3 = 70GB  (/home)

This way everything is mirrored and everything is in one VG.  If you
need more space, add another pair of mirrored drives and add the new
mirrored device into VolGroup00.  Then you can use the space to expand
whichever filesystem needs it.  I would also advise following the
previous poster's advice and leaving a few GB unused so that you
aren't forced to add more drives immediately when LV2 fills up faster
than you expected.

-- 
Bowie