[CentOS] mkswap, lvm and bootbits sectors

No, afaict there's nothing wrong with your lvm. The only problem I see is that
mkswap prints our an incorrect or at least pointless warning.

I can confirm that mkswap on an lv on one of my test machines also says
"warning: don't erase bootbits...". It also says this when running against a
file full of zeroes...

Regarding fdisks complaints about "doesn't contain a valid partition
table...", this is normal (and may be considered a bug in the "-l" option, it
could have excluded lvm-devices from its list...).

If you want to get to the bottom of this I suspect the easiest way is to look
at the mkswap source code (under which circumstances it prints that message).

/Peter