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I've added a new 3TB hdd to my Ubuntu Server 12.04 system for media (already has another drive for the OS), but it's only showing 2.2TB capacity

df -H


/dev/sdb1                      2.2T  208M  2.2T   1% /media/hd1


fdisk -l


Disk /dev/sdb: 3000.6 GB, 3000592982016 bytes
90 heads, 3 sectors/track, 21705678 cylinders, total 5860533168 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: 0x29fbcbef

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1            2048  4294967294  2147482623+  83  Linux




            description: ATA Disk
            product: WDC WD30EZRX-00M
            vendor: Western Digital
            physical id: 1
            bus info: scsi@1:0.0.0
            logical name: /dev/sdb
            version: 80.0
            serial: WD-WCAWZ2859923
            size: 2794GiB (3TB)
            capabilities: partitioned partitioned:dos
            configuration: ansiversion=5 signature=29fbcbef
               description: EXT4 volume
               vendor: Linux
               physical id: 1
               bus info: scsi@1:0.0.0,1
               logical name: /dev/sdb1
               logical name: /media/hd1
               version: 1.0
               serial: dbb920f9-989b-4494-957f-23a6b758030b
               size: 2047GiB
               capacity: 2047GiB
               capabilities: primary journaled extended_attributes large_files huge_files dir_nlink recover extents ext4 ext2 initialized
               configuration: created=2012-11-10 22:21:07 filesystem=ext4 lastmountpoint=/media/hd1 modified=2012-11-10 23:27:27 mount.fstype=ext4 mount.options=rw,relatime,user_xattr,barrier=1,data=ordered mounted=2012-11-10 23:14:02 state=mounted

I followed the instructions on https://help.ubuntu.com/community/InstallingANewHardDrive (command line) to partition, format and mount the drive.

I'm not sure what I've done wrong, any ideas?

P.S. fdisk -l also states

WARNING: GPT (GUID Partition Table) detected on '/dev/sda'! The util fdisk doesn't support GPT. Use GNU Parted.

Not sure if that makes a difference?

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It looks like the partition isn't taking up the entire disk. Can you check in Parted? –  hexafraction Nov 11 '12 at 0:15
There is still some confusion about base-2 and base-10. Also, by default, a new filesystem usually reserves 5% for root. That is rather extreme for such a large filesystem. It's difficult to imagine the root user requiring 150GB disk space. –  Jo-Erlend Schinstad Nov 11 '12 at 0:58
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1 Answer

up vote 1 down vote accepted

It seems you've used fdisk or one of the ext2 tools to partition the drive. The maximum disk size for an MBR partitioned disk is indeed 2.2TB. You need the to have GUID partition table to exceed this limit. Here's a wikipedia page.

The error message you got seems to suggest using Gparted to format this drive, so the implication is that Gparted understands GUID partition tables and can write them.

You will still appear to lose some of the capacity as the drive manufacturers say '3TB' when what they actually mean is 3,000,000,000 bytes, which is actually about 2.7 real TB. As stated you will also appear to 'lose' about 5% for filesystem tables and allocations for an ext4 partition. Actually, the 5% is based on 512bytes/sector and I don't think that will apply in this case. The final figure may be a bit different. You might also want to watch your inodes if you're going to have a lot of small files on this drive - the number (of inodes) can't be changed easily later so do your research.

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Your BIOS needs to be compatible with a GUID partition table, too. The gdisk program from the gdisk package is similar to fdisk and can partition a GUID partition table. –  John S Gruber Nov 11 '12 at 5:51
@JohnSGruber:Thanks John, I had a feeling that I'd forgotten something. –  fabricator4 Nov 11 '12 at 8:00
Thanks @fabricator4. With this info and some googling I eventually sorted it, with some help from these instructions: cyberciti.biz/tips/…. It wasn't completely straight forward, I think I should have unmounted the 2nd hdd first and removed it from fstab to prevent problems rebooting. Also worth noting is the UUID changed after I changed the partition label/type and size. –  neilcrookes Nov 11 '12 at 16:17
If, unlike this question, one were replacing the boot disk with another, larger one and a partition on that drive was desired that contained more than 2.2 TB, it would be necessary to back up all data (of course) create the GPT partition table and format them, as above, copy the data to the new drive, and reinstall grub. grub core doesn't fit on a GPT formatted drive where it goes on an legacy formatted drive, so it would probably be best to create a separate partition just for grub. –  John S Gruber Nov 11 '12 at 18:42
A minor correction: The BIOS doesn't need to support GPT, although some broken BIOSes do flake out when they see GPT. This can usually be worked around. See rodsbooks.com/gdisk/bios.html for details. Also, gdisk (at the referenced site) can convert from MBR to GPT format without data loss, although you'll then need to either resize the partition or create a new one to take advantage of the space. When installed on GPT from a BIOS-based computer, GRUB works best with a BIOS Boot Partition, which is best placed early on the disk. –  Rod Smith Nov 12 '12 at 0:23
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