On Dec 19, 2008, at 11:56 AM, erik quanstrom wrote:
Two questions:
1. But before I ask this one: I don't deny that per-file append-
only
is *extremely* useful. My question is a different one: what is
the danger of N clients accesing the file X in append-only mode
and M clients accesing it in random access mode? Could you,
please, give a concrete scenario?
credit geoff for bringing this up: upas mailboxes.
suppose you have upas/deliver trying to deliver a message and at
the same time you have upas/fs trying to rewrite the mailbox.
(play along for a bit. ignore L.mbox and the temporary mbox
tricks.)
It is difficult to answer your question without knowing what rewrite
actually does and how mailboxes are structured. But in an imaginary
world where a mailbox is a list of constant sized blocks (size<iounit)
a bunch of simultaneous appends and rewrites of existing blocks
would work perfectly well.
Thanks,
Roman.
