Re: Does Linux support more than 2TB on a USB attached device?

On Tue, 2 Oct 2007 14:11:23 -0700 Richard Sharpe wrote:

> Hi,
> 
> I hope that this is not an oft repeated question, but recently during
> testing we encountered the following errors:
> 
> Oct  2 18:43:12 red-gemini mail-notification: No worthy mechs found
> Oct  2 18:45:55 red-gemini kernel: sd 7:0:0:0: [sdb] Very big device.
> Trying
> to use READ CAPACITY(16).
> Oct  2 18:45:55 red-gemini kernel: sd 7:0:0:0: [sdb] READ CAPACITY(16)
> failed
> Oct  2 18:45:55 red-gemini kernel: sd 7:0:0:0: [sdb] Result:
> hostbyte=DID_ABORT driverbyte=DRIVER_OK,SUGGEST_OK
> Oct  2 18:45:55 red-gemini kernel: sd 7:0:0:0: [sdb] Use 0xffffffff as
> device size
> Oct  2 18:45:55 red-gemini kernel: sd 7:0:0:0: [sdb] 4294967296 512-byte
> hardware sectors (2199023 MB)
> Oct  2 18:45:55 red-gemini kernel: sd 7:0:0:0: [sdb] Write Protect is
> off
> Oct  2 18:45:55 red-gemini kernel: sd 7:0:0:0: [sdb] Assuming drive
> cache:
> write through
> Oct  2 18:45:55 red-gemini kernel:  sdb:
> 
> I think we were returning 0x67FFFFFFF as the max LAB in the READ
> CAPACITY(16).
> 
> Is there something special we need to enable in Linux to allow for more
> than 2TB on a USB device?

There was a mail thread on linux-kernel mailing list just a few days
ago ("Truncated Filesystem").  The short answer is that MS-DOS
style partition tables have a 2 TB limit.  There are at least
2 ways around that.  One is to use device mapper to group multiple
partitions into a larger logical device (I don't know details of
how to do this).  The other that was suggested in that thread
is to use 'parted' to make the partition(s) instead of using
fdisk (or sfdisk or cfdisk).


Here's the lkml thread:  http://lkml.org/lkml/2007/9/28/387

parted is here http://www.gnu.org/software/parted/index.shtml
if your distro doesn't have it.

---
~Randy

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