USB thumb drives as /usr filesystem

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

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

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 
org       |

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

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.

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

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.

Bob,

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

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 
Web: http://www.satsignal.eu

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).

It gets warm but not hot. I'd guess about 30-35C.

That's the same stick.

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

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