I am seeing a discrepancy between the output of mdadm --detail and mdadm --examine, and I don't understand why.
This output
mdadm --detail /dev/md2
/dev/md2:
Version : 0.90
Creation Time : Wed Mar 14 18:20:52 2012
Raid Level : raid10
Array Size : 3662760640 (3493.08 GiB 3750.67 GB)
Used Dev Size : 1465104256 (1397.23 GiB 1500.27 GB)
Raid Devices : 5
Total Devices : 5
Preferred Minor : 2
Persistence : Superblock is persistent
Seems to contradict this. (the same for every disk in the array)
mdadm --examine /dev/sdc2
/dev/sdc2:
Magic : a92b4efc
Version : 0.90.00
UUID : 1f54d708:60227dd6:163c2a05:89fa2e07 (local to host)
Creation Time : Wed Mar 14 18:20:52 2012
Raid Level : raid10
Used Dev Size : 1465104320 (1397.23 GiB 1500.27 GB)
Array Size : 2930208640 (2794.46 GiB 3000.53 GB)
Raid Devices : 5
Total Devices : 5
Preferred Minor : 2
The array was created like this.
mdadm -v --create /dev/md2 \
--level=raid10 --layout=o2 --raid-devices=5 \
--chunk=64 --metadata=0.90 \
/dev/sdg2 /dev/sdf2 /dev/sde2 /dev/sdd2 /dev/sdc2
Each of the 5 individual drives have partitions like this.
Disk /dev/sdc: 1500.3 GB, 1500301910016 bytes
255 heads, 63 sectors/track, 182401 cylinders, total 2930277168 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: 0x00057754
Device Boot Start End Blocks Id System
/dev/sdc1 2048 34815 16384 83 Linux
/dev/sdc2 34816 2930243583 1465104384 fd Linux raid autodetect
Backstory
So the SATA controller failed in a box I provide some support for. The failure was a ugly and so individual drives fell out of the array a little at a time. While there are backups, we the are not really done as frequently as we really need. There is some data that I am trying to recover if I can.
I got additional hardware and I was able to access the drives again. The drives appear to be fine, and I can get the array and filesystem active and mounted (using read-only mode). I am able to access some data on the filesystem and have been copying that off, but I am seeing lots of errors when I try to copy the most recent data.
When I am trying to access that most recent data I am getting errors like below which makes me think that the array size discrepancy may be the problem.
Mar 14 18:26:04 server kernel: [351588.196299] dm-7: rw=0, want=6619839616, limit=6442450944
Mar 14 18:26:04 server kernel: [351588.196309] attempt to access beyond end of device
Mar 14 18:26:04 server kernel: [351588.196313] dm-7: rw=0, want=6619839616, limit=6442450944
Mar 14 18:26:04 server kernel: [351588.199260] attempt to access beyond end of device
Mar 14 18:26:04 server kernel: [351588.199264] dm-7: rw=0, want=20647626304, limit=6442450944
Mar 14 18:26:04 server kernel: [351588.202446] attempt to access beyond end of device
Mar 14 18:26:04 server kernel: [351588.202450] dm-7: rw=0, want=19973212288, limit=6442450944
Mar 14 18:26:04 server kernel: [351588.205516] attempt to access beyond end of device
Mar 14 18:26:04 server kernel: [351588.205520] dm-7: rw=0, want=8009695096, limit=6442450944
