Help a Newbie on Linux-Raid 1

I am rather new to linux and decided to set up a system using linux raid on centos 5.2 Being new I find some howtos easy to follow and I used one in setting up the raid. All looked fine when I finished and everything was was in order showing working raid and then I did a stupid thing and stopped the machine to make sure each drive could boot. Stopping the machine between drive swaps. THis all worked well then I configured the machine and a few days latter I noticed that the raid was showing degraded on both drives.

Now being a newbie I am in a bind. The machine is still running and after spending many hours configuring it, I do not want to screw it up so I look to someone with lots more knowledge than I for help.

Please help with full command lines to solve this issue and get the raid rebuilt as I do not want to screw anything up. I have included the information on the system below. If anything else is needed please let me know.

Many thanks in advance guys.....

Dan

/var/log/dmesg

ata1.00: ATA-7: ST3250310AS, 4.AAA, max UDMA/133 ata1.00: 488397168 sectors, multi 16: LBA48 NCQ (depth 0/32) ata1.00: configured for UDMA/133
ata2.00: ATA-7: ST3250310AS, 4.AAA, max UDMA/133 ata2.00: 488397168 sectors, multi 16: LBA48 NCQ (depth 0/32) ata2.00: configured for UDMA/133
Vendor: ATA Model: ST3250310AS Rev: 4.AA
Type: Direct-Access ANSI SCSI revision: 05
SCSI device sda: 488397168 512-byte hdwr sectors (250059 MB)
sda: Write Protect is off
sda: Mode Sense: 00 3a 00 00
SCSI device sda: drive cache: write back
SCSI device sda: 488397168 512-byte hdwr sectors (250059 MB)
sda: Write Protect is off
sda: Mode Sense: 00 3a 00 00
SCSI device sda: drive cache: write back
sda: sda1 sda2
sd 0:0:0:0: Attached scsi disk sda
Vendor: ATA Model: ST3250310AS Rev: 4.AA
Type: Direct-Access ANSI SCSI revision: 05
SCSI device sdb: 488397168 512-byte hdwr sectors (250059 MB)
sdb: Write Protect is off
sdb: Mode Sense: 00 3a 00 00
SCSI device sdb: drive cache: write back
SCSI device sdb: 488397168 512-byte hdwr sectors (250059 MB)
sdb: Write Protect is off
sdb: Mode Sense: 00 3a 00 00
SCSI device sdb: drive cache: write back
sdb: sdb1 sdb2
sd 1:0:0:0: Attached scsi disk sdb
device-mapper: uevent: version 1.0.3
device-mapper: ioctl: 4.11.5-ioctl (2007-12-12) initialised:
[email protected]

md: Autodetecting RAID arrays.
md: autorun ...
md: considering sdb2 ...
md:  adding sdb2 ...
md: sdb1 has different UUID to sdb2
md:  adding sda2 ...
md: sda1 has different UUID to sdb2
md: created md1
md: bind<sda2>
md: bind<sdb2>
md: running: <sdb2><sda2>
md: kicking non-fresh sda2 from array!
md: unbind<sda2>
md: export_rdev(sda2)
raid1: raid set md1 active with 1 out of 2 mirrors
md: considering sdb1 ...
md:  adding sdb1 ...
md:  adding sda1 ...
md: created md0
md: bind<sda1>
md: bind<sdb1>
md: running: <sdb1><sda1>
md: kicking non-fresh sda1 from array!
md: unbind<sda1>
md: export_rdev(sda1)
raid1: raid set md0 active with 1 out of 2 mirrors
md: ... autorun DONE.

kjournald starting. Commit interval 5 seconds
EXT3-fs: mounted filesystem with ordered data mode.

# cat /proc/mdstat
Personalities : [raid1]
md0 : active raid1 sdb1[1]
      104320 blocks [2/1] [_U]

md1 : active raid1 sdb2[1]

      244091520 blocks [2/1] [_U]

unused devices: <none>

# /sbin/mdadm -D /dev/md1
/dev/md1:
        Version : 00.90.03
  Creation Time : Sat Nov  8 13:31:37 2008
     Raid Level : raid1
     Array Size : 244091520 (232.78 GiB 249.95 GB)
  Used Dev Size : 244091520 (232.78 GiB 249.95 GB)
   Raid Devices : 2
  Total Devices : 1
Preferred Minor : 1
    Persistence : Superblock is persistent

Update Time : Tue Dec 2 08:06:57 2008
State : clean, degraded
Active Devices : 1
Working Devices : 1
Failed Devices : 0
Spare Devices : 0

UUID : 86e86a3b:8e87f809:12ea81c3:2a8cb750
Events : 0.743680

Number Major Minor RaidDevice State
0 0 0 0 removed
1 8 18 1 active sync /dev/sdb2

# /sbin/mdadm -D /dev/md0
/dev/md0:
        Version : 00.90.03
  Creation Time : Sat Nov  8 13:33:46 2008
     Raid Level : raid1
     Array Size : 104320 (101.89 MiB 106.82 MB)
  Used Dev Size : 104320 (101.89 MiB 106.82 MB)
   Raid Devices : 2
  Total Devices : 1
Preferred Minor : 0
    Persistence : Superblock is persistent

Update Time : Mon Dec 1 10:26:34 2008
State : clean, degraded
Active Devices : 1
Working Devices : 1
Failed Devices : 0
Spare Devices : 0

UUID : de04b561:d5722aa5:39fbf8b1:b8b8884b
Events : 0.210

Number Major Minor RaidDevice State
0 0 0 0 removed
1 8 17 1 active sync /dev/sdb1

View this message in context: http://www.nabble.com/Help-a-Newbie-on-Linux-Raid-1-tp20995732p20995732.html
Sent from the linux-raid mailing list archive at Nabble.com.

Assuming nothing is bad with the other drive, you just need to add it back into the RAID-1 array (after you are done testing)

mdadm /dev/md0 -a /dev/sda1
mdadm /dev/md1 -a /dev/sda2

This will re-add the other drive partitions back into the raid1 array.

It will not re-add automatically if you disconnected one drive to test the RAID-1 functionality.

       ^^^^^^^^^

       ^^^^^^^^^

Justin.