Tonight I'll present on backups; what to backup and how to backup, and
how to recreate Apple’s Time Machine with a one line command. The
presentation will be about 30-45 minutes and we’ll socialize after —
stay as long as you want to — if you have any computer questions,
bring ‘em!

See you tonight.

- Seth

Weber County Main Library, Board Room
2464 Jefferson Ave.
Ogden, UT 84401

rsync -a $HOME/ /var/timemachine/$USER/`date '+%FT%R'`

Then put this in your crontab (all on one line):

1   */2   *   *   *   BACKUPDIR=/var/timemachine/$USER; rsync -a
--link-dest=$BACKUPDIR/`/bin/ls -t $BACKUPDIR | head -1` $HOME/
$BACKUPDIR/`date '+%FT%R'`

I've been working on some scripts for this, and I'm going to work on a
python plugin for nautilus that adds right click functionality like
"revert to version as of DATE". If anyone is interested, I'll share
the finished products here.

@months = ("Jan", "Feb", "Mar", "Apr", "May", "Jun",
           "Jul", "Aug", "Sep", "Oct", "Nov", "Dec");
($sec,$min,$hour,$mday,$mon,$year,$wday,$yday,$isdst) = localtime();
$year += 1900;
$now = sprintf("%02d $months[$mon] $year %02d:%02d:00",$mday,$hour,$min);

&read_datefile();

if ($level > 0) {
    $prev = $level - 1;

    while ($prev > 0) {
        if ($levels{"$fs:$prev"}) {
            last;
        }
        $prev--;
    }

if ($prev < $level && ($prevd = $dates{"$dir:$prev"})) {
    $targs .= " --newer-mtime '$prevd'";
    print STDERR "Previous Level: $prev\n";
    print STDERR "Previous Time:  $prevd\n";

if (!$writeout) {
    exit(0);

open(DATES, ">$datefile") || die("open(>$datefile): $!\n");
$dates{"$dir:$level"} = $now;
for $k (sort keys (%dates)) {
    ($fs, $lv) = split(/:/, $k);
    print DATES "$fs $lv $dates{$k}\n";

&release_lock();

sub lopen {
    my ($fd, $fname) = @_;
    my $retry;

    if (!open($fd, $fname)) {
        print(STDERR "open($fd, \"$fname\"): $!\n");
        return 0;
    } # || return 0;
    $retry = $lopen_retry || 5;

    return $fd;

    while (!flock($fd, $LOCK_EX|$LOCK_NB)) {
        if (!$retry) {
            print STDERR "Cannot lock file: $fname ($!)\n";
            return 0;
        }
        $retry--;
        sleep(1);
    }

    if ($fname =~ /^>>/) {
        ## make sure we are at the end--now that we have a lock
        seek($fd, 0, $SEEK_END);
    } else {
        ## make sure we are at the start--now that we have a lock
        seek($fd, 0, $SEEK_SET);
    }

    return $fd;

    close($file);
    flock($file, $LOCK_UN);

This article was about 5 years old, and from what I understand,
unionfs has been vastly improved performance wise.

I'll run some benchmarks later this week.

On 7/4/09, brandon <b...@solv.com> wrote:

The big surprise came from new file creation. The speed of that was
only a small fraction of the original performance, though still high -
bonnie++ still measured several thousand files per second. I guess the
lesson here is that while this may be suitable for desktops, on many
server systems with many dynamic files it may not work.

Other performance indicators like read and write speeds were a touch
slower but very close to original.