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Old 02-25-2014, 06:48 PM   #1
zinny
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Vgcreate


Please what does it really mean... Physical extent size must be a power of 2. I have PE 20 to use for volume group and 32M for logical volume. I made a partition of 700M then run the following commands.

Pvcreate /dev/vda6
Vgcreate -s 20 vg /dev/vda6 Then I got the output

Physical extent volume size must be a power of 2.

Please explain this to me as man page didn't give me much thing to go with. Am new to this area.

Thank you
 
Old 02-25-2014, 06:53 PM   #2
Ser Olmy
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Powers of two are any "2 raised to the power X" , such as 1, 2, 4, 8, 16, 32 and so on.

Edit: Oh, and "extents" are the allocation units inside a Volume Group. When you create a logical volume, a certain number of extents are allocated.

Last edited by Ser Olmy; 02-25-2014 at 06:58 PM.
 
Old 02-25-2014, 07:00 PM   #3
zinny
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Thanks for your response.
In my case with PE 20, does it mean 2 to the power of 20, that is
Vgcreate -s 2^20 /dev/vda6
 
Old 02-25-2014, 07:05 PM   #4
Ser Olmy
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No... where does the number "20" come from? Do you want your extents to be 20 kilobytes in size? Or 20 megabytes?

The default extent size is 4 Mb. Is there a specific reason why you want to change it?
 
Old 02-25-2014, 07:17 PM   #5
zinny
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The question is to create a volume group with physical extent set as 20M and logical volume of 32M. So when I run
Vgcreate -s 20M /dev/vda I got

Physical extent size must be in a power of 2.



Create a volume group and set 20M as extents. And divided a volume group containing 32M on volume group (lvshare).

Last edited by zinny; 02-25-2014 at 07:23 PM.
 
Old 02-25-2014, 08:37 PM   #6
Ser Olmy
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20 isn't a power of two, so that's not a permitted extent size. The extent size can be 16 Mb or 32 Mb, but not 20.
 
Old 02-25-2014, 08:45 PM   #7
zinny
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Thanks so much, I can see I misunderstood the question.
 
  


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