Re: [linux-lvm] How do you create large numbers of LVs? (In the 1000s) Is it even possible?

[Ming Zhang <mingz@ele.uri.edu>]

On Thu, 2005-07-28 at 12:09 -0700, Nathaniel Stahl wrote:
> We'd like to be able to create a large number of LVs (potentially 
> numbering in the low thousands).  I get failure after LV 226 or so, 
> though - "VG VolGroup01 metadata writing failed".
> 
> RedHat claims this should be possible with LVM2 on the following web page:
> 
> http://www.redhat.com/magazine/009jul05/features/lvm2/
> 
> I admit to being a little suprised at the 2^32 max LV claim - I was 
> figuring 2^20 as the theoretical max given 2.6's 32 bit device numbering 
> scheme (20 bits for minor, 12 bits for major).
> 
> The LVM2 code, at least version 2.00.25 as distributed in FC3, appears 
> to have a check that the minor number is strictly less than 256.  
> Removing this check allows for the creation of working LVs using minors 
> greater than 256, but LV creation fails with the error "VG VolGroup01 
> metadata writing failed" creating the 227th LV.  Even with the minor 
> limit in place - I can't create more than 226 LVs.

i asked this question before. there is a hard coded limitation in lvm
metadata, so the real number is like this, limited around 2xx. the
limitation will be removed in near future. how near? i do not know. :)


> 
> Is there a patch that allows this limit to be broken?  Should I be using 
> a newer version of the tools?  If not currently possible, is this 
> something that will be in the near future?
> 
> Thanks for any help/advice you can give.
> 
> -Nate Stahl
> 
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