[lug] NAS recommendations?

Paul E Condon pecondon at mesanetworks.net
Mon Oct 26 14:39:55 MDT 2009

On 20091026_120558, Michael J. Hammel wrote:
> On Mon, 2009-10-26 at 11:41 -0600, George Sexton wrote:
> > I use plain old USB drives. I have 3-4 with the same enclosure. I just
> > attach one to the server, and dump to it. Every month or so, when one
> > fills up, I put it in my media safe and pull the next one in the
> > rotation out of the safe.
> Has anyone had any problems with the Western Digital USB MyBooks?  Or
> more importantly:  has anyone had USB ports on the motherboard flake out
> and take a USB drive with it?
> I have a motherboard that has a bunch of USB ports.  I plugged in two
> 500GB MyBooks with no problem.  They've worked for quite some time. I
> plugged in a 1TB MyBook and the system began to act badly.  Turns out
> the BIOS doesn't support that drive and won't boot with it plugged in.
> But now at least one of the drives (a 500GB) is dying.  I can use it for
> awhile on another machine (not the original - it doesn't work there at
> all now) but then it dies and I can no longer access it.  The other
> 500GB seems to be okay and the 1TB I'm not sure about yet.
> I don't know whether the USB ports might have caused this because I
> plugged in the 1TB and the hardware didn't like it or this is just
> coincidental and the 500GB was just about to die anyway.  I'm confused
> since all the other MyBooks I have (6 total between work and home) are
> all working just fine.
> This may also just be related to heat since the room these are in gets
> quite warm in the summer.  It's my home office and I have to leave a fan
> running 24/7 and the window open to keep the place cool.

I have a Mybook and a Passport, both 500GB. I've had the Passport
longer, and did have some trouble with it. I think it did get a little
too warm and started reporting errors last spring. I un-plugged it,
let it cool down and tried to restart it. It was running ext3. Error
message said I needed to run fsck. I did and there were _many_ errors
reported and eventually the run of fsck died. After many tries to
recover the file system I gave up on the data and just out of
curiosity ran mkfs.ext3 on it. That completed without errors and the
drive has worked fine ever since (>3mo). Then I got the Mybook and run
the two somewhat in parallel, doing the same backup on alternate
days. I prefer the Passport for personal backups since I really can
envision myself grabbing it on the way out the door in case of fire,
etc.  It does fit in a pocket so hands are free to grab children, etc.

A related comment on using USB for backup. Use rsync to update the backup, 
but not with --delete. Instead look at --link-dest=XXX, e.g.

The prior backup is in file structure rooted in XXX/ on the USB. 
Using --delete the command would be

(cd /media/USB; rsync -av --delete <source>/ XXX )

Instead, create a new, empty directory, YYY/ on the USB and run

 (cd /media/USB; rsync -av --link-dest=XXX/ <source>/ YYY )

This creates a hard link in YYY for each file that already has an
up-to-date backup in XXX/. You get in YYY/ the same thing as you would
have gotten had you used --delete, but you still have yesterday's
backup in XXX/ The actual disk usage for the new backup is just the
files that have actually changed. Read the man page. It says it better
than I do. The choice of name for this option is based on the
perception that hard link has a 'destination' that is the inode to
which the directory entry in XXX already points. The destination for
rsync is YYY, contrary to what you might think if you read the man
page too quickly.

In actual practice, the backup root directories XXX and YYY should
contain the date. Since the actual turnover of files in a personal
backup is quite small, you might reasonably keep a years worth of
daily images on a single Mybook or Passport. But --- you might want to
do as I do. Run two drives this way in parallel, especially in summer

As you collect old daily images, you will reach a limit on the link
count of files that are new every day. Ext2 does not support more
than 32000 hard links to a single inode. My rough calculation is that
you can do daily backups, without deletions, for almost 22 years.

Paul E Condon           
pecondon at mesanetworks.net

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