Brett Serkez spake the following on 4/1/2007 3:04 PM:> 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
Does the board have an onboard fakeraid? I think that is what DMRAID does. It
supports some of the fakeraid controllers, although it is much less mature
than plain software raid.
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