XFS journaling position

[klonatos at ics.forth.gr]

Hello,

     I have recently discovered that the default journalling position of
XFS is in the "middle" AG, if the log is internal (e.g. for 32 AGs
the journal will be placed at the AG = 16). Although I am aware that
there is possible to explicitly specify a journal location using the
-l agnum=X mkfs option, I am really curious about the resoning behind
the default choice.

Thanks in advance,
Yannis Klonatos