Afternoon,
my 6x 2tb raid5 got moved into a different server, which has more
drives available. Before the move the system was using an intel sata2
ahci on board controller. Nothing special. Instead of creating a
partition I pointed to the entire device aka /dev/sdc instead of
/dev/sdc1. Running an fdisk against the drive doesn't come back with
anything, but that is expected
The new system uses a promise 16300 sata pci-x controller. Slower, but
that system has more slots for drives. The drives got presented as a
jbod through the raid controller bios. Right away on the boot up the
linux system identified all the drives and put the /dev/md0 device
together.
Currently mdadm adjusted every partition table. Running fdisk against
any of the volumes comes back with this:
Disk /dev/sdd: 2000.4 GB, 2000398934016 bytes, 3907029168 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0xffffffff
This doesn't look like a partition table
Probably you selected the wrong device.
Device Boot Start End Blocks Id System
/dev/sdd1 ? 4294967295 8589934589 2147483647+ ff BBT
/dev/sdd2 ? 4294967295 8589934589 2147483647+ ff BBT
/dev/sdd3 ? 4294967295 8589934589 2147483647+ ff BBT
/dev/sdd4 ? 4294967295 8589934589 2147483647+ ff BBT
Yesterday for testing purposes I failed a drive, cleaned the partition
table and then re-added it. The Disk identified got reset back to
0xffffffff and the partition table looks the same again.
/dev/md0:
Version : 1.1
Creation Time : Sat Apr 17 13:39:21 2010
Raid Level : raid5
Array Size : 9767567360 (9315.08 GiB 10001.99 GB)
Used Dev Size : 1953513472 (1863.02 GiB 2000.40 GB)
Raid Devices : 6
Total Devices : 6
Persistence : Superblock is persistent
Update Time : Thu Dec 13 09:33:38 2012
State : clean, degraded, recovering
Active Devices : 5
Working Devices : 6
Failed Devices : 0
Spare Devices : 1
Layout : left-symmetric
Chunk Size : 256K
Rebuild Status : 35% complete
Name : amy:0
UUID : d64bd5fc:be602828:04c0c8c0:312502d9
Events : 2919684
Number Major Minor RaidDevice State
6 8 32 0 active sync /dev/sdc
7 8 112 1 active sync /dev/sdh
8 8 64 2 active sync /dev/sde
9 8 48 3 active sync /dev/sdd
5 8 80 4 active sync /dev/sdf
10 8 96 5 spare rebuilding /dev/sdg
The reason why I stared this work was to identify why my raid is so
unbelievable slow at writing. Reading is a file is around 100mb/s, but
writing is currently at 40mb/s. On my previous sata2 controller i got
read/ writes between 450-650mb/s.
Alex
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