- I have a server with six 4TB drives running Ubuntu 14.04 LTS.
- One of the drives is used for the system/OS
- I wanted to use the other 5 drives to get as close to 20TB of storage as possible
- It's a short term data analysis project, so RAID 0 is fine
- I used fdisk to create a single ~4TB partition on each of the 5 drives
After running mdadm to create a RAID 0 array, the result was just a 10TB device on /dev/md0. Half the size that I was expecting!
Here is the command that I used to create the array:
mdadm --create --verbose /dev/md0 --level=stripe --raid-devices=5 /dev/sd[bcdef]1
Below is an fdisk -l
output. Any ideas on why I can't get more space out of the drives?
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 / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000
Device Boot Start End Blocks Id System
/dev/sda1 1 4294967295 2147483647+ ee GPT
Disk /dev/sdb: 4000.8 GB, 4000787030016 bytes
90 heads, 3 sectors/track, 28940878 cylinders, total 7814037168 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: 0xda4f04e2
Device Boot Start End Blocks Id System
/dev/sdb1 2048 4294967294 2147482623+ 83 Linux
Disk /dev/sdc: 4000.8 GB, 4000787030016 bytes
25 heads, 3 sectors/track, 104187162 cylinders, total 7814037168 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: 0xc9e57616
Device Boot Start End Blocks Id System
/dev/sdc1 2048 4294967294 2147482623+ 83 Linux
Disk /dev/sdd: 4000.8 GB, 4000787030016 bytes
25 heads, 3 sectors/track, 104187162 cylinders, total 7814037168 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: 0x53bed1ab
Device Boot Start End Blocks Id System
/dev/sdd1 2048 4294967294 2147482623+ 83 Linux
Disk /dev/sde: 4000.8 GB, 4000787030016 bytes
25 heads, 3 sectors/track, 104187162 cylinders, total 7814037168 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: 0xbc5c1069
Device Boot Start End Blocks Id System
/dev/sde1 2048 4294967294 2147482623+ 83 Linux
Disk /dev/sdf: 4000.8 GB, 4000787030016 bytes
25 heads, 3 sectors/track, 104187162 cylinders, total 7814037168 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: 0x4801480c
Device Boot Start End Blocks Id System
/dev/sdf1 2048 4294967294 2147482623+ 83 Linux
Disk /dev/md0: 10995.1 GB, 10995108413440 bytes
2 heads, 4 sectors/track, -1610614656 cylinders, total 21474821120 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 524288 bytes / 2621440 bytes
Disk identifier: 0x00000000
Disk /dev/md0 doesn't contain a valid partition table
/dev/sdX1
partitions is only about half of each actual disc (about 4.3Gsectors, out of 7.8Gsectors)? That would certainly explain why you're missing so much space.fdisk
should never be used on drives larger than 2TB. These require GPT parititoning to use their full space. Usegdisk
orparted
instead.