[CentOS] CentOS 5 Dual Drive Confusion

Sun Apr 1 22:04:52 UTC 2007
Brett Serkez <bserkez at gmail.com>

I performed a test install of CentOS Beta 5 on a system with two ~60
GB drives.  When installing CentOS 4 on this system, I normally work
thru setting up Software RAID with identically sized partitions on
each drive.

For my test, the CentOS installer only presented a single drive.  I
took the default of letting it do what it wanted.  After looking over
the system I have verified that /boot is using DMRAID, but it isn't
not clear if the balance of the drive for the root file system is
using both drives or not, I think it might be.

Using fdisk, I can see both disks are carved out identically:

   Device Boot      Start         End      Blocks   Id  System
/dev/hda1   *           1          13      104391   83  Linux
/dev/hda2              14        7297    58508730   8e  Linux LVM

/dev/hdd1   *           1          13      104391   83  Linux
/dev/hdd2              14        7297    58508730   8e  Linux LVM

Using dmraid it *looks* like the drives are mirrored in total?

dmraid -r -D
/dev/hda: pdc, "pdc_bacfgfjaf", mirror, ok, 117231345 sectors, data@ 0
/dev/hdd: pdc, "pdc_bacfgfjaf", mirror, ok, 117231345 sectors, data@ 0

But then using df it is less obvious:

df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/mapper/VolGroup00-LogVol00    54G 1009M   50G   2% /
/dev/mapper/pdc_bacfgfjafp1             99M   11M   83M  12% /boot
tmpfs                 125M     0  125M   0% /dev/shm

pvs shows VolGroup00 as using pdc_bacfgfjafp2:

PV                          VG         Fmt  Attr PSize  PFree
  /dev/mapper/pdc_bacfgfjafp2 VolGroup00 lvm2 a-   55.78G 32.00M

which is RAID1??????

Seems to be:

dmraid -s
*** Active Set
name   : pdc_bacfgfjaf
size   : 117231232
stride : 128
type   : mirror
status : ok
subsets: 0
devs   : 2
spares : 0

Am I properly understanding that by default, CentOS 5 is creating a
full drive mirrored RAID?  Then for other than the boot partition, it
is laying LVM over this mirrored RAID, presumably to allow adjustments
later?

Thank you in advance,

Brett