[linux-lvm] The maximum size of a Logical volume

[吴德新 <wudx05@gmail.com>]

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From LVM2 FAQ,  I get the following answer*:

4.1.13. * What is the maximum size of a single LV?

* * The answer to this question depends upon the CPU architecture of your
computer and the kernel you are a running:

   -

   For 2.4 based kernels, the maximum LV size is 2TB. For some older
   kernels, however, the limit was 1TB due to signedness problems in the block
   layer. Red Hat Enterprise Linux 3 Update 5 has fixes to allow the full 2TB
   LVs. Consult your distribution for more information in this regard.
   -

   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.)



But I want to why the maximum size is 16TB on 32-bit CPU.  With LBD (large
block device) is configured,  kernel use u64 to represent sector number, so
the capacity of a block device can become more than 16TB.  Where is the
limitation ?  Thanks.

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