[mythtv-users] myth_archive_job.pl and it's Use. (And Side effects of use)

[Tony Lill]

Since you're always recording to a NAS box, it seems a bit silly to
copy the files from one nfs mount to another. Instead, make your
recording directory a symlink to point to the emptiest mount point,
and change it when it gets too full.

I've been running the following script to switch my recording dir
between 3 filesystems. It's run from cron 5 minutes after the half
hour. The min free space is enough to hold 2 movies, plus a bit (since
I have 2 encoders). When it changes the symlink to the recording dir,
it fixes/creates/deletes symlinks as necessary.

#!/usr/bin/perl -w
#
# By A. J. Lill, with bits from myth_archive_job.pl

#
# Values are: "DIRECTORY:FREESPACE"
#
# Free Space is in Megabytes
#
my( @ArchiveDirEntries ) = (
	"/misc/f1/myth:10240",
	"/misc/f2/myth:10240",
	"/misc/f3:10240"
	);

my( $curmount ) = readlink "/u/myth";
my( $bestdir) ;
my $bestfree = 0;
my( $dirEntry);
foreach $dirEntry ( @ArchiveDirEntries ) {
  my( $archiveDir, $keepFree ) = split( ':', $dirEntry );
  my( $freeSpace ) = GetFreeSpace( $archiveDir );
  
  if( $#ARGV < 0 && $archiveDir eq $curmount && $freeSpace - $keepFree > 0 ) {
    # If we're below the freespace threshold, don't bother. Any
    # argument forces a switch
    exit(0);
  }
  if( $freeSpace - $keepFree > $bestfree ) {
    $bestdir = $archiveDir;
    $bestfree = $freeSpace - $keepFree;
  }
}

if( $#ARGV > 0 ) {
  $bestdir = $ARGV[1];
}

if( ! $bestdir ) {
	exit 0;
}

if( $bestdir ne $curmount ) {
  unlink "/u/myth";
  symlink( $bestdir, "/u/myth");
  chdir $curmount;
  foreach $i ( glob "*.{nuv,mpg}*" ) {
    $link = readlink $i;
    if( defined( $link ) ) {
      if( ! -f "$bestdir/$i" ) {
	symlink( $link, "$bestdir/$i" );
      }
      unlink $i;
    } else {
      symlink( "$curmount/$i", "$bestdir/$i" );
    }
  }
}

exit(0);


# Don't like doing this, but it was easier than requiring Filesys::Statfs
sub GetFreeSpace {
	my( $dir ) = shift;

	if ( ! -r $dir ) {
		return 0;
	} else {
		my( $freeSpace ) = `df -m $dir | grep -v Available | awk '{print \$4}'`;

		return $freeSpace;
	}
}