[colug-432] MicroSD cards: exFAT or ext?

[Rob Stampfli]

On Thu, Feb 07, 2013 at 10:43:19AM -0500, Scott Merrill wrote:
> I have a PogoPlug which I use primarily as an ssh end point for screen
...
>   http://en.wikipedia.org/wiki/MicroSD#File_system
> See the "Risks of reformatting" section.
> 
> I'm curious if any folks here can share personal experiences with
> reformatting SDXC cards to use native Linux filesystems?  How's the
> performance? The longevity?
> 
> Alternately, can folks report success or failure using the exfat-fuse
> libraries to access exFAT formatted partitions?

I have several PogoPlugs running from hard drives.  I've booted them
from thumb drives for testing, but the only Unix device I've ever run
from an SD card is my SheevaPlug.  For that I use an ext2 root file
system.  (I chose ext2 instead of ext3 or 4 because it cuts down on
the number of write cycles.)

My assessment:  SD cards are fast!  Much faster than spinning media.
However, I'm on my second card on the Sheeva.  The first one was a
16GB generic SD from Microcenter.  It ran fine, but after a year or so
I began noticing some strange and growing file system corruption each
time I fscked it.  With some investigation, I discovered that the card
was generating random bit errors.  I did this by comparing my various
backups -- each was worse than the pervious one.  (Obviously, that
meant my backups were toast, a rather nasty bug!)  I replaced the card
with some fast SD-card that Franco wanted to get rid of.  As we all
know, Franco only buys quality stuff, and this card has apparently been
working fine.  My Sheeva has been up and running for 220 days now, so
it is probably time to fsck the partition again.  I use it for spooling
TV shows I want to record to an attached HD.

Since your Pogo doesn't have a built-in SD card slot, I'd suggest
skipping the SD card and just going with a thumb drive.  These devices
are so inexpensive now that you can easily buy two or three and use the
spares for on-the-shelf backups.  Then if your thumb drive ever does
take a dive, you can just plug in the backup and you're back up and
running, well, unless your thumb drive has a failure mode similar to
my Microcenter drive.

YMMV,
Rob