[mythtv] [mythtv-commits] Ticket #7949: Multiple identical partitions on identical drives are listed as only one Mythtv drive

[f-myth-users at media.mit.edu]

    > Date: Wed, 03 Feb 2010 13:49:22 -0500
    > From: Dan Wilga <mythtv-dev2 at dwilga-linux1.amherst.edu>

    > On 2/3/10 1:19 PM, Chris Pinkham wrote:
    > > I've been considering the possibility of having the master resolve
    > > the situation automatically without waiting for a recording by having
    > > the affected backends write out a random-sized 0-10 megabyte file

    > Why not just write a zero-length file with a unique name to each drive, 
    > and see if any file exists in more than one place? Surely a directory 
    > read or fopen would be faster than recalculating free space a second time.

That's the same thing -I- suggested 11-ish hours ago when I restarted
the thread, and Chris pointed out that it doesn't work:  SG's might
be placed on disjoint directories that share a filesystem, so your
nonces will appear unique but in fact share a filesystem.  [Granted,
even sharing a -disk- is an issue for load-balancing, but I'm not
sure how Myth is ever supposed to figure -that- out in a robust
and portable way.]  You should go back and check the whole thread.

The "random-length files" thing is the second thing I suggested,
which is also hardly an original idea (unsurprising); see Chris's
snippet above.

The third thing I suggested was the "punt it back to the user by
issuing a disclaimer if we see a situation that Myth is unlikely
to get right without a bunch more possibly-error-prone code",
which at least has the virtue of adding nothing but an "if" and
a string to the codebase.