Re: [linux-lvm] LVM2 with disks greater than 2TB

[Judd Tracy <jtracy@ist.ucf.edu>]

I recall having a similar problem when I setup a large array a long time 
ago and it was related to the partition table if I remember correctly.  
I wish I could remember more, but that was atleast 2 years ago.  
Hopefully it can lead you in the right direction.  I think I ended up 
using and EFI partion table if I remember correctly.

Judd

Dan wrote:

> What concerns me is if I just try and make a single 4.54TB partition 
> as reiserfs without using LVM2 and mount it, it still only shows up as 
> ~560GB using df -h.  This makes me think it maybe an os issue.  Any 
> thoughts?
>
> Barnaby Claydon wrote:
>
>> Dan wrote:
>>
>>> I have 24 - 500GB drives raided such that 11 drives + 1 hot spare 
>>> per raid to get 4.54TB times 2.  I want to use LVM2 to make this 
>>> into one ~9TB disk, but when I create the partitions and do a df -h 
>>> they show up as about 560GB each instead of 4.5TB each.  I do an 
>>> fdisk -l and they show up correctly.  I am using Slackware 10.0.  I 
>>> have device-mapper and LVM2 correctly installed.  I am obviously 
>>> hitting a 2TB limit from what I have read, but does anyone know if 
>>> it is possible to even do what I want?  If so, any suggestions on 
>>> what I need to install to get this to work?  I am running the 
>>> 2.6.15.4 kernel.  Thanks
>>>
>> Dan, from the LVM2 FAQ ( 
>> http://www.tldp.org/HOWTO/LVM-HOWTO/lvm2faq.html ) it mentions:
>>
>> * For 32-bit CPUs on 2.6 kernels, the maximum LV size is 16TB.
>> * For 64-bit CPUs on 2.6 kernels, the maximum LV size is 8EB. (Yes, 
>> that is a very large number.)
>>
>> From what I recall when I built my last LVM, it's a matter of setting 
>> the PE size during creation (hopefully you haven't started filling 
>> with data yet). I think the default causes you to hit the 2TB limit, 
>> but it can definitely be set higher. The default PE Size seems to 
>> depend on Linux distribution, but mine is at 4MB and I'm at 1.5TB 
>> right now so the references to a 32MB default would definitely get 
>> you to 9TB.
>>
>> Sorry I can't offer any other specifics - hope that helps.
>>
>> -Barnaby
>>
>>
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>
>
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-- 
Judd Tracy
University of Central Florida
Institute for Simulation and Training
jtracy@ist.ucf.edu
407-882-1479