[mythtv-users] USB Flash Memory for boot/system. What is fast enough?

Brian Wood beww at beww.org
Mon Nov 23 14:48:44 UTC 2009


On Monday 23 November 2009 07:22:13 Jim Stichnoth wrote:
> On Sun, Nov 22, 2009 at 2:59 PM, Andrew Close <aclose at gmail.com> wrote:
> > i'm planning out a Zotac IONITX-B-E Atom N230 FE and am looking to
> > boot/run off of a USB stick.  what speed is fast enough to limit any
> > hiccups during playback/menu navigation?  i wouldn't think it would be
> > a huge deal since the USB stick will just contain the OS and FE while
> > all content would be coming over the wire, but i've seen mention of
> > slow USB sticks causing issues.
> > most of the sticks i've looked at list their speed at 200x, but what
> > does that mean?  i've only seen a few that have any r/w performance
> > listed. any thoughts/suggestions?
>
> My experience is that you need to worry about more than the "up to
> 200x" or whatever rating the manufacturer gives.
>
> My first USB stick had some sort of bulk write problem.  If I did too
> much sustained writing, I would get an I/O error and Linux would stop
> recognizing the drive until I reinserted it.  This is clearly a
> problem if you're trying to install the OS onto the USB stick or clone
> an existing OS.
>
> My second USB stick was fine for bulk writes, but had some other sort
> of problem.  During myth playback, every 5-30 minutes or so, playback
> (and presumably the whole system as well) would pause for a couple
> seconds.  I tried cloning it back to a hard drive and it ran
> flawlessly for a week, so I'm certain it was a problem with the USB
> stick.
>
> For my third stick, I decided to choose something with hundreds of
> high Newegg ratings.  This led me to the "Patriot Xporter XT Boost"
> line, which was rock solid for as long as I used it.  I recommend the
> 8GB size.  4GB was enough for me, until I started installing this
> package and that, until it pushed a little over 4GB.
>
> By the way, be sure to use the "noatime" option when mounting file
> systems on the USB stick.  Otherwise every file that is opened, even
> for reading, will actually involve another write to the file system.
>
> Of course, in the spirit of ION systems and minimalism, your next step
> is obviously to set up your system for net-booting. :)  How to do this
> may be obvious to many or well-documented elsewhere, but I documented
> my own experience on this list.
> http://www.gossamer-threads.com/lists/mythtv/users/391239


The problem with flash drives is they generally state the size and the price, 
and that's about it. The many other factors are never even mentioned. If you 
go to the manufacturer's site you can sometimes find more info, but not 
always. I'm always afraid of specs that start with "up to", those two words, 
as used by ISPs, sometimes actually mean "something above zero".

In addition to using the "noatime" mounting option, you also want to make sure 
you are not swapping to partition on a flash device.

It's hard to say  though, I have a system running Debian Sarge from a 1GB 
flash stick that's been running for over two years with no problems (NSLU2 
system), and I did not use noatime, and I am swapping to a partition on that 
stick. IOW I did everything "wrong", and have had no problems.

Running entire systems from flash devices seems to be the ultimate "YMMV" 
situation. Fortunately the devices are cheap enough to allow for considerable 
experimentation.



-- 
Brian Wood
beww at beww.org


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