[CentOS] DatOptic RAID Array >2TB?

Joshua Baker-LePain jlb17 at duke.edu
Fri Jun 8 01:22:24 UTC 2007

On Thu, 7 Jun 2007 at 8:19pm, Benjamin Karhan wrote

> in fact, the kernel "USB Mass Storage" driver that detects the
>  array when i plug it in only detects the device as 2TB as well.
>  (so, it could easily be a limitation of that hardware driver,
>  although i couldn't find any specification for that limitation
>  when i googled for it).

My googling seemed to indicate that, yes, the USB mass storage protocol 
(not just the Linux driver, but the protocol itself) is limited to 2TB per 

> i should say, although i dread the possible suggestions that may
>  arise from admitting it, that the array also supports FireWire
>  and SATA connections.  (we are STRONGLY inclined to wanting to
>  use the array as USB, as our primary concern is easy portability
>  and not speed)

I can't see anything that says Firewire has the same 2TB limitation as 
USB.  So that's worth a shot.

> the RAID array is the DatOptic eRAID, with 5 750GB disks in a
>  RAID-5 array.  the array itself seemed to have no problem
>  creating the ~3TB volume, but it does not detect as that
>  size when i hook it up.

Many such devices have an "auto-carve" feature (or some such), that 
automatically splits one RAID volume into <2TB chunks, each on a different 
LUN.  If you're married to USB, see if your hardware will do that.

Joshua Baker-LePain
Department of Biomedical Engineering
Duke University

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