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I created a RAID5 array from the bios of 3 Nos of 4TB disks. Then I created a Volume in Bios which shows as 6.9TB. But in ubuntu this volume is shown as 3.2TB.

Why is this so and how can I correct this?

fdisk-l shows as below. Disk /dev/mapper/isw_feefadaab_Pictures: 3203.4 GB is the problematic partition.

Disk /dev/sda: 4000.8 GB, 4000787030016 bytes
255 heads, 63 sectors/track, 486401 cylinders, total 7814037168 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/sda doesn't contain a valid partition table

Disk /dev/sdb: 4000.8 GB, 4000787030016 bytes
255 heads, 63 sectors/track, 486401 cylinders, total 7814037168 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/sdb doesn't contain a valid partition table

Disk /dev/sdc: 4000.8 GB, 4000787030016 bytes
255 heads, 63 sectors/track, 486401 cylinders, total 7814037168 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/sdc doesn't contain a valid partition table

Disk /dev/sdd: 512.1 GB, 512110190592 bytes
255 heads, 63 sectors/track, 62260 cylinders, total 1000215216 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: 0x000d2c3e

   Device Boot      Start         End      Blocks   Id  System
/dev/sdd1            2048        4095        1024   83  Linux
/dev/sdd2   *        4096     1003519      499712   83  Linux
/dev/sdd3         1003520   251002879   124999680   82  Linux swap / Solaris
/dev/sdd4       251002880  1000214527   374605824   83  Linux

Disk /dev/sde: 512.1 GB, 512110190592 bytes
255 heads, 63 sectors/track, 62260 cylinders, total 1000215216 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: 0x00000000

Disk /dev/sde doesn't contain a valid partition table

Disk /dev/sdf: 512.1 GB, 512110190592 bytes
255 heads, 63 sectors/track, 62260 cylinders, total 1000215216 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: 0x00000000

Disk /dev/sdf doesn't contain a valid partition table

Disk /dev/md127: 512.0 GB, 511975817216 bytes
2 heads, 4 sectors/track, 124994096 cylinders, total 999952768 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: 0x00000000

Disk /dev/md127 doesn't contain a valid partition table

Disk /dev/mapper/isw_feefadaab_Pictures: 3203.4 GB, 3203399942144 bytes
255 heads, 63 sectors/track, 389457 cylinders, total 6256640512 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 65536 bytes / 131072 bytes
Disk identifier: 0x00000000

Disk /dev/mapper/isw_feefadaab_Pictures doesn't contain a valid partition table
  • Is this partition going to be accessible from another OS, or just from Linux? Just wondering, the answer to this will change my answer to your dilemma. – darkdragn Jan 25 '16 at 15:24
  • Only from Linux – DeeJay Jan 25 '16 at 15:32
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I know this isn't what most people want to hear, however Linux doesn't always play nice with 'fakeraid' that is baked into your BIOS. Instead, I would recommend using a software raid, namely MDADM. You would have to undo your fakeraid, and go back to normal disks first.

Example for mdadm RAID 5:

  1. Install MDADM

apt-get install mdadm

  1. Create raid. Adjust drive names accordingly. You don't need to use partitions, you can do whole disks:

mdadm --create --verbose /dev/md0 --level=5 --raid-devices=3 /dev/sdb1 /dev/sdc1 /dev/sdd1 --spare-devices=1 /dev/sde1

Then enjoy the security of RAID5, and use the device /dev/md0 as your raid device.

If you need more help, go straight to the source: https://raid.wiki.kernel.org/index.php/RAID_setup

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