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

[Dan <lvm@the-rusty-nail.com>]

I was just reading up on some things from 3ware which is who makes the 
cards I am using.  They say to use gnu parted instead of fdisk because 
fdisk doesn't support > 2TB disks.  I am not sure if this still holds 
true since the article was from June 2004 but I will try it and let 
everyone know how I make out.

Judd Tracy wrote:
> 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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>>> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
>>
>>
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>
>
>