$ cat /proc/mdstat
Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4] [raid10]
md126 : active (auto-read-only) raid1 sdb1[2]
483266368 blocks super 1.2 [2/1] [_U]
md127 : active (auto-read-only) raid1 sdb5[2]
4981696 blocks super 1.2 [2/1] [_U]
unused devices: <none>
$ sudo fdisk -l
Disk /dev/sda: 400.1 GB, 400088457216 bytes
255 heads, 63 sectors/track, 48641 cylinders, total 781422768 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: 0x000d48d7
Device Boot Start End Blocks Id System
/dev/sda1 * 63 775939499 387969718+ 83 Linux
/dev/sda2 775939500 780132464 2096482+ 5 Extended
/dev/sda5 775939563 780132464 2096451 82 Linux swap / Solaris
Disk /dev/sdb: 500.1 GB, 500107862016 bytes
255 heads, 63 sectors/track, 60801 cylinders, total 976773168 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk identifier: 0x26f580a8
Device Boot Start End Blocks Id System
/dev/sdb1 * 2048 966797311 483397632 fd Linux raid autodetect
/dev/sdb2 966799358 976771071 4985857 5 Extended
Partition 2 does not start on physical sector boundary.
/dev/sdb5 966799360 976771071 4985856 fd Linux raid autodetect
Disk /dev/md127: 5101 MB, 5101256704 bytes
2 heads, 4 sectors/track, 1245424 cylinders, total 9963392 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk identifier: 0x00000000
Disk /dev/md127 doesn't contain a valid partition table
Disk /dev/md126: 494.9 GB, 494864760832 bytes
2 heads, 4 sectors/track, 120816592 cylinders, total 966532736 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk identifier: 0x00000000
Disk /dev/md126 doesn't contain a valid partition table