[CentOS] Installation problems with large mirrored drives

Wed Feb 6 21:56:58 UTC 2008
John R Pierce <pierce at hogranch.com>

Bowie Bailey wrote:
..... md, lvm, etc...


I make /boot a standalone partition as /dev/sda0  and later manually 
copy it to /dev/sdb0 which I mount as /boot2
I make a hda2 on each drive as a swap, mirrored as /dev/md1
I make a hda3 on each drive, mirror as /dev/md0, then make this a LVM, 
and all my system partitions are created in this LVM.  its messy, but it 
works.


here's some of the config of a simple dual IDE drive CentOS 5 box I 
setup for some tests...


# fdisk -l

Disk /dev/hda: 500.1 GB, 500107862016 bytes
255 heads, 63 sectors/track, 60801 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

   Device Boot      Start         End      Blocks   Id  System
/dev/hda1   *           1          13      104391   83  Linux
/dev/hda2              14          79      530145   82  Linux swap / Solaris
/dev/hda3              80       60801   487749465   fd  Linux raid 
autodetect

Disk /dev/hdb: 500.1 GB, 500107862016 bytes
255 heads, 63 sectors/track, 60801 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

   Device Boot      Start         End      Blocks   Id  System
/dev/hdb1   *           1          13      104391   83  Linux
/dev/hdb2              14          79      530145   82  Linux swap / Solaris
/dev/hdb3              80       60801   487749465   fd  Linux raid 
autodetect

# mdadm --misc --detail /dev/md0
/dev/md0:
        Version : 00.90.03
  Creation Time : Mon Jul 23 03:21:50 2007
     Raid Level : raid1
     Array Size : 487749376 (465.15 GiB 499.46 GB)
    Device Size : 487749376 (465.15 GiB 499.46 GB)
   Raid Devices : 2
  Total Devices : 2
Preferred Minor : 0
    Persistence : Superblock is persistent

    Update Time : Wed Feb  6 13:50:07 2008
          State : clean
 Active Devices : 2
Working Devices : 2
 Failed Devices : 0
  Spare Devices : 0

           UUID : 0b01feb0:fcd82e29:fc464a34:7e30e91a
         Events : 0.4

    Number   Major   Minor   RaidDevice State
       0       3        3        0      active sync   /dev/hda3
       1       3       67        1      active sync   /dev/hdb3

# lvm pvdisplay
  --- Physical volume ---
  PV Name               /dev/md0
  VG Name               VolGroup00
  PV Size               465.15 GB / not usable 29.75 MB
  Allocatable           yes
  PE Size (KByte)       32768
  Total PE              14884
  Free PE               284
  Allocated PE          14600
  PV UUID               w5489v-kCEo-tbY9-hwLl-GME0-x1wL-XjMSrC
  
# lvm lvdisplay
  --- Logical volume ---
  LV Name                /dev/VolGroup00/LogVol00
  VG Name                VolGroup00
  LV UUID                O7rU30-CQKO-18tJ-Vo1L-Zcxh-bOjk-00MM9C
  LV Write Access        read/write
  LV Status              available
  # open                 1
  LV Size                19.53 GB
  Current LE             625
  Segments               1
  Allocation             inherit
  Read ahead sectors     0
  Block device           253:0
  
  --- Logical volume ---
  LV Name                /dev/VolGroup00/LogVol02
  VG Name                VolGroup00
  LV UUID                CUybA0-qRDq-HYEI-fxtX-f4YU-XVST-dmoC7G
  LV Write Access        read/write
  LV Status              available
  # open                 1
  LV Size                397.66 GB
  Current LE             12725
  Segments               2
  Allocation             inherit
  Read ahead sectors     0
  Block device           253:1
  
  --- Logical volume ---
  LV Name                /dev/VolGroup00/LogVol01
  VG Name                VolGroup00
  LV UUID                hkx0s2-XaGt-WPzq-8vzS-fi3I-1z3C-MX41Uj
  LV Write Access        read/write
  LV Status              available
  # open                 1
  LV Size                39.06 GB
  Current LE             1250
  Segments               1
  Allocation             inherit
  Read ahead sectors     0
  Block device           253:2
  
# df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/mapper/VolGroup00-LogVol00
                       19G  1.7G   17G  10% /
/dev/hda1              99M   17M   78M  18% /boot
/dev/hdb1              99M  5.6M   89M   6% /boot1
tmpfs                 252M     0  252M   0% /dev/shm
/dev/mapper/VolGroup00-LogVol02
                      386G  291G   75G  80% /home
/dev/mapper/VolGroup00-LogVol01
                       38G  882M   36G   3% /var



and, here's the applicable anaconda-ks.cfg entries that got created at 
install time...

clearpart --linux
part /boot --fstype ext3 --size=100 --asprimary
part swap --size=520 --ondisk=hdb
part swap --size=520 --ondisk=hda --asprimary
part /boot1 --fstype ext3 --size=100 --ondisk=hdb --asprimary
part raid.4 --size=100 --grow --ondisk=hdb
part raid.3 --size=100 --grow --ondisk=hda
raid pv.6 --fstype "physical volume (LVM)" --level=RAID1 --device=md0 
raid.3 raid.4
volgroup VolGroup00 --noformat --pesize=32768 pv.6
logvol / --fstype ext3 --name=LogVol00 --vgname=VolGroup00 --size=20000
logvol /var --fstype ext3 --name=LogVol01 --vgname=VolGroup00 --size=40000
logvol /home --fstype ext3 --name=LogVol02 --vgname=VolGroup00 --size=100000


(ok, I lied, I didn't mirror my swap, I really should fix that)