[Discuss] SSD

Edward Ned Harvey blu at nedharvey.com
Tue Jun 5 09:20:35 EDT 2012


> From: discuss-bounces+blu=nedharvey.com at blu.org [mailto:discuss-
> bounces+blu=nedharvey.com at blu.org] On Behalf Of Tom Metro
> 
> Edward Ned Harvey wrote:
> > ...that's why things like ZFS and BTRFS implement OS-level
> > checksumming of filesystems...
> >
> > USB flash drives don't all have FEC or any error correction at all.  I
have
> > actually experienced enough bit errors from USB fobs, that I simply
don't
> > use them for anything anymore.  If I need usb storage, I use a hard
drive or
> > nothing.
> 
> Why not use an error correcting file system on them?

It's difficult for me to build a Mac OSX Installation USB fob (or ubuntu
install fob) that uses ZFS in the backend.   ;-)  Also, users frequently ask
me, "I have this USB fob, and I need to copy some files between mac &
windows.  I can see it with this system, but not that system...  what can I
do?"   I have to format their drive with MBR and FAT.

What other filesystems do checksumming anyway?  Not Mac, not NTFS, not
ext3/4...  The only ones I know are BTRFS and ZFS, which are generally
unavailable anywhere you would care about using a USB fob.

The situations I've most often actually *experienced* corrupted bits from
USB fob were from OS installation, mac & ubuntu.  The thing is ... Generally
speaking, you don't know that corruption has occurred.  Simply, some little
detail after installation, doesn't quite work properly, and you would never
be able to track it down to the USB fob, unless you have a large scale to
work on...

I'll name my experience of 3 weeks ago:  I created an OSX installation USB
fob.  I installed 3 systems from it.  Everything was fine, until the last
step of my "golden image" process.  When I tried to enable filevault, I got
some random-ass error that made no sense.  So I created a USB installation
hard disk instead, repeated the same process, and got a better result.

And various other similar situations...

Sure, on occasion, I see a hard disk that returns incorrect bits.  But it's
much more rare than the USB fob returning incorrect bits.




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