[CentOS] 3TB External USB Drive isn't recognized
Lamar Owen
lowen at pari.edu
Tue Aug 13 15:13:26 UTC 2013
On 08/12/2013 12:21 PM, John R Pierce wrote:
> ... and MBR disks have an absolute maximum size of 2TB
Actually, no. The size of disk usable in an MBR partitioning scheme is
dependent upon the disk's block size; with 4k blocks MBR can (and does)
go above 2TB. We actually have a pair of Western Digital 3TB externals
that are NTFS-formatted and MBR partitioned. Yes, this is non-standard
and breaks the 'letter' of the MBR specs, but, it works fine on Windows,
which is the target audience. The Mac-formatted Studio drives are GPT
partitioned (and cost more). The Linux HFS and HFS+ filesystem drivers
don't like the 3TB HFS+ formatted WD Studio 3TB I have here, either......
see: http://forums.anandtech.com/archive/index.php/t-2174705.html and
the comment by Mark R down the page a bit. Seagate and WD both do this
with external 3TB drives meant for PCs.
WD does something very similar for their MyBookLive models; these units
are the network-attached ones, and 3TB single-drive and 6TB dual-drive
units are common. The NAS embedded OS is Linux, and the main data
partition is formatted 64k-blocksize ext4:
(This is on a 1TB model....)
LOMBL1:~# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/md0 1.9G 541M 1.3G 30% /
tmpfs 5.0M 0 5.0M 0% /lib/init/rw
udev 10M 6.7M 3.4M 67% /dev
tmpfs 5.0M 0 5.0M 0% /dev/shm
tmpfs 100M 10M 90M 10% /tmp
ramlog-tmpfs 20M 3.4M 17M 17% /var/log
/dev/sda4 924G 922G 2.5G 100% /DataVolume
LOMBL1:~# tune2fs -l /dev/sda4
tune2fs 1.41.12 (17-May-2010)
Filesystem volume name: <none>
Last mounted on: /CacheVolume
Filesystem UUID: 2631203b-3cb5-4f63-b9ae-12fed7e5d0bd
Filesystem magic number: 0xEF53
Filesystem revision #: 1 (dynamic)
Filesystem features: has_journal ext_attr resize_inode dir_index
filetype needs_recovery extent flex_bg sparse_super large_file huge_file
uninit_bg dir_nlink extra_isize
Filesystem flags: unsigned_directory_hash
Default mount options: (none)
Filesystem state: clean
Errors behavior: Continue
Filesystem OS type: Linux
Inode count: 15144960
Block count: 15191355
Reserved block count: 0
Free blocks: 892140
Free inodes: 14734611
First block: 0
Block size: 65536
Fragment size: 65536
Reserved GDT blocks: 32
Blocks per group: 65528
Fragments per group: 65528
Inodes per group: 65280
Inode blocks per group: 255
Flex block group size: 16
Filesystem created: Thu Apr 7 19:26:05 2011
Last mount time: Tue Jun 4 16:02:59 2013
Last write time: Tue Jun 4 16:02:59 2013
Mount count: 15
Maximum mount count: 29
Last checked: Thu Apr 7 19:26:05 2011
Check interval: 15552000 (6 months)
Next check after: Tue Oct 4 19:26:05 2011
Lifetime writes: 1173 GB
Reserved blocks uid: 0 (user root)
Reserved blocks gid: 0 (group root)
First inode: 11
Inode size: 256
Required extra isize: 28
Desired extra isize: 28
Journal inode: 8
Default directory hash: half_md4
Directory Hash Seed: 4a2c0236-2d62-4779-bb5b-950094980616
Journal backup: inode blocks
LOMBL1:~#
LOMBL1:~# parted /dev/sda print
Model: ATA WDC WD10EACS-00Z (scsi)
Disk /dev/sda: 1000GB
Sector size (logical/physical): 512B/512B
Partition Table: gpt
Number Start End Size File system Name Flags
3 15.7MB 528MB 513MB linux-swap(v1) primary
1 528MB 2576MB 2048MB ext3 primary raid
2 2576MB 4624MB 2048MB ext3 primary raid
4 4624MB 1000GB 996GB ext4 Microsoft basic data
LOMBL1:~# cat /etc/debian_version
5.0.4
LOMBL1:~# uname -a
Linux LOMBL1 2.6.32.11-svn70860 #1 Thu May 17 13:32:51 PDT 2012 ppc
GNU/Linux
LOMBL1:~#
Oh, but 64k blocksize ext4 is NOT supported on almost all PC linux
distributions, including CentOS..... At least it's not a funky MBR
format, and GPT is used.... And yet the MyBookLive runs Debian
5.0.4/PPC...... Go figure. For more info on the MyBookLive from a linux
point of view, see http://mybookworld.wikidot.com/ (it's a fun box to
play with, and much more robust than the previous 'World Edition' drives).
CentOS works fine with the SMB shares the MBL exports, and I'm using one
right for backups.
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