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From: Zdenek Kabelac <zkabelac@redhat.com>
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Date: Thu, 26 Jul 2018 10:58:24 +0200
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Subject: Re: [linux-lvm] Trying to understand format of LVM2 - Question on
	Extent Size
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To: LVM general discussion and development <linux-lvm@redhat.com>, "David F." <df7729@gmail.com>

Dne 26.7.2018 v 06:25 David F. napsal(a):
> Never mind, the answer is the extent_size is the number of sectors (or perhaps 
> it's the number of 512 byte blocks, I'll have to test on 4K sector 
> drives).     So in this case 4M and 4M*3840 is the 16G (not 16M which was the 
> 3840*4096).
> 
> On Wed, Jul 25, 2018 at 5:37 PM, David F. <df7729@gmail.com 

Hi


extent_size is always in 512b unit  and ATM it's 32b value.


extent_count is in 'extent_size' unit  and ATM it's 32b value.


Volume size    extent_size * extent_count   (so  32b * 32b =>  64b size).


Depending on your extent_size you are limiting maximum volume size.
Thus if you need to use  Exa byte volume sizes you clearly need to go with 4G 
extent size.


Regards


Zdenek