Last week I got another set of drives for my system — 1x 2TB drive to be hooked up to the computer and 2x 2TB drives to be my rotating backup drives.

(I do feel strange ordering up 6TB worth of drives from Amazon)

So the process goes something like this: move some big directories from the first two drives (1.5TB and 2TB) onto the new 2TB drive then start to back things up again. No problem right?

Well, on drive two (I have is labeled Backup1ExFw20A) it started to do some thrashing when backing things up.

Fragmentation? Let’s format it and try again. It’s a backup anyway and I have another backup already off-site so I don’t have any real issue with formatting my backup.

The rsync started off fine at aroung 20MB/s but within an hour it was back to thrashing the heads. I let it run overnight and when I woke up I saw it spontaneously unmount the drive mid-write.

Gaaahhh!

(I think the USB dock was the blame in this case since I had to power-cycle the USB-SATA dock to get it to recognize any drive)

I don’t like potentially corrupt backups so I started over.

It did the same thing again, though this time it took only a few hours to unmount.

When I reset the dock and remounted the drive I hit Command-Space to start up spotlight to start something up.

“Indexing BackupExFw20A…”

Ah-ha!

The thrashing was Spotlight trying to index the backup!

I turned it off for the backup drive and immediately things were quiet again.

I reformatted the backup one last time for good measure and turned off Spotlight for it (and the other two backup drives) and things have been smooth even since.

BTW – Here’s my backup script in case anyone is interested in doing something similar:

#! /bin/bash

if [ -d /Volumes/BackupExFw15A ]
then
    rsync -av --delete --exclude='/.Spotlight-V100' \
      --exclude='/.Trashes' --exclude='/.fseventsd' \
      --filter='P /.Spotlight-V100' --filter='P /.fseventsd' \
      --exclude='*~' /Volumes/ExFw15A/ \
      /Volumes/BackupExFw15A
elif [ -d /Volumes/BackupExFw20A ]
then
    rsync -av --delete --exclude='/.Spotlight-V100' \
      --exclude='/.Trashes' --exclude='/.fseventsd' \
      --filter='P /.Spotlight-V100' --filter='P /.fseventsd' \
      --exclude='*~' /Volumes/ExFw20A/ \
      /Volumes/BackupExFw20A    
elif [ -d /Volumes/BackupExFw20B ]
then
    rsync -av --delete --exclude='/.Spotlight-V100' \
      --exclude='/.Trashes' --exclude='/.fseventsd' \
      --filter='P /.Spotlight-V100' --filter='P /.fseventsd' \
      --exclude='*~' /Volumes/ExFw20B/ \
      /Volumes/BackupExFw20B
else
    echo "No backup device found."
fi

I used to have different scripts per backup drive but I didn’t want to continue the pattern as I grew from two to three drives. Now all I have to do I slap in a drive and “sudo backup” and away we go!