USB thumb drives as /usr filesystem

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Can anybody suggest a USB thumb drive with write speeds that
can support a mounted filesystem on an RPI2? There seem to be
problems using inexpensive USB 2.0 drives (I'm using a Kingston
DataTraveler 8 GB at the moment). It runs hot, and write intensive
processes tend to time out.

It's tempting to think that a USB 3.0 device might be an improvement.
The read speed advantage is obviously lost on a USB 2.0 host, but the
write speed necessitated by the faster interface might be helpful,
even at the lower data link speed offered by USB 2.0.  

Something like the SanDisk Extreme USB 3.0 series comes to mind.....

Has anybody tried it?

Thanks for reading,

bob prohaska
  



Re: USB thumb drives as /usr filesystem
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Yes - not on a Pi, but for a similar application.  That would be my
recommended USB stick at the moment - it's quick and random write
performance is pretty reasonable.

Theo

Re: USB thumb drives as /usr filesystem
Theo Markettos wrote:

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Be aware that a power disruption during a write /may/ kill it.  

Happened to me with a SanDisk Cruzer, went RO and unreadable, no way of  
recovering it.

fruit

Re: USB thumb drives as /usr filesystem
On Mon, 26 Oct 2015 10:42:09 +0000, fruit wrote:

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A UPS designed for the RPI (yes, there are or were some available for  
reasonable prices) or a suitably sized capacitor (5-10 thousand  
microFarads) across the RP's PSU, preferably with a one or 2 ohm wire  
wound resistor in series with it, should help with power interruptions.


--  
martin@   | Martin Gregorie
gregorie. | Essex, UK
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Re: USB thumb drives as /usr filesystem
Martin Gregorie wrote:

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Obviously but I can buy a lot of USB sticks for the cost of adding a UPS to  
each of mine!

One of my Pis and a Cubie are attached to a standard UPS.  

The one that died was set up as a minimal portable machine with Pi camera -  
worth the risk of bits failing - even the Pi itself

fruit


Re: USB thumb drives as /usr filesystem
On 26/10/2015 01:37, User Bp wrote:
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Be aware of marketing power. You can add a USB3 interface but still use  
a low spec microcontroller and slow Flash. That lets you say USB3 on the  
box because it is USB3 but doesn't mean it's faster than a USB2 stick. I  
have plenty of USB3 sticks that are just very slow.

Branded USB3 should be better than unknown cheap sticks but check specs  
or get a real recommendation before you buy anything.

Re: USB thumb drives as /usr filesystem
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I've just ordered a SanDisk Extreme 32 GB USB 3.0 thumb drive. Should
have it tomorrow, will let folks know how it behaves. The reviews seem
decent, but nobody mentions how hot it runs.

Thanks for all the replies!

bob prohaska


Re: USB thumb drives as /usr filesystem
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Always test the devices to make sure you have not been ripped off.
It is quite usual that you receive e.g. a 8 GB device marked (and formatted)
as 32 GB.

Re: USB thumb drives as /usr filesystem
On 27 Oct 2015 08:06:09 GMT

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That may well be true if you buy the cheapest you can find from somebody
you've never heard of on eBay. It shouldn't be a problem if you buy
from a reputable etailer (but check anyway, just to be sure).


Re: USB thumb drives as /usr filesystem
On 27/10/2015 01:39, User Bp wrote:
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Bob,

I was  looking for backup devices to replace rewritable DVDs on a PC,  
and came up with this:

  
(Amazon.com product link shortened)

as a compromise between speed and cost.  I measured a couple of them on  
a USB 3.0 motherboard port using H2testW.:

   SanDisk USB 3.0 32 GB #1 - write 98.0 MB/s, read 206 MB/s

   SanDisk USB 3.0 32 GB #3 - write 93.6 MB/s, read 210 MB/s

Good luck with yours.

Cheers,
David
--  
Cheers,
David
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Re: USB thumb drives as /usr filesystem
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It gets warm but not hot.  I'd guess about 30-35C.

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That's the same stick.

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It's random read/write performance that matters for OS performance.  On
CrystalDiskMark (using an NTFS filesystem on the stick and a USB 3.0 port on
Windows 8.1), I get:

Read:
Seq Q32 T1 196.2MB/s
4K Q32 T1 12.97MB/s
Seq 240.4MB/s
4K 9.805 MB/s

Write:
Seq Q32 T1 101.5MB/s
4K Q32 T1 11.22MB/s
Seq 100.7MB/s
4K 10.83 MB/s

(5 runs, 1GiB transfer)

The 4K random write speeds are some of the best I've seen on USB sticks - not
far off low-end SSDs, and miles better than SD cards.

Theo

Re: USB thumb drives as /usr filesystem
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Funny how mechanical and solid state storage shows similar performance patterns....

The SanDisk Extreme showed up after lunch and is being set up now. It formatted
to 29.75 GB out of 32GB nominal capacity, so nothing's amiss on that score.  

Heatwise it's hard to tell; the case is plastic, I agree it's not much warmer
than body temp, but plastic is a much worse heat conductor than the metal  
used to enclose the (scary hot) Kingston that's being replaced. Not at all
obvious what the internal temp is. It does seem the total power dissipation
is less.  

The activity light is a helpful feature, which the Kingston lacks

Has anybody seen lifespan numbers for these devices?

Thanks for reading,

bob prohaska


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