I read a bit more about the issue the last days. What is still not clear to me, does a USB flash drive typically fail because the memory cells are worn out (times a memory cell can be written is limited) or is it more likely that another part of the electronics fails?

Generally there are SLC, MLC and TLC memory cells. Numbers I found how often these can be written are 50k (SLC), 3k (MLC) and 1k (TLC) times before they fail. SLC is not common any more in USB flash drives as well as in SSDs, except for some industrial applications. However, using MLC memory could be worth it. Most cheap USB flash drives as well as SSDs use TLC memory these days.

USB flash drives with MLC memory, for example the Transcend Jet Flash 780 costs about 15 EUR / 18 USD for the 16 GB version. Prices for other sticks using MLC memory I found were comparable (unfortunately, not all manufacturers are transparent about what memory they use). Even if wearing out of the memory cells is not the deciding factor, one could hope that also the other components are better and less likely to fail at higher priced USB flash drives. The very high speed of most MLC sticks compared to other USB flash drives may be nice but without a large advantage for WCG.

With SSDs the decision for MLC or TLC memory may be a bit different. If chosing a drive with high capacity (e.g. 128, 256 or more GB), TLC might be ok, as with the higher number of memory cells the writes spread over a larger number of cells. With lower capacity drives (which might be the best choice, as a cruncher needs not much memory), MLC might be better.
Generally, my hope is, that even the worst SSDs are more reliable than most USB flash drives, not because there is any reason USB flash drives could not also be reliable, but simply because consumers are less willing to accept failures on their primary drive than on a memory stick, as well as the generally higher price, which leaves more room for quality components.

To make things short, I ordered the following:

Transcend MTS400S SATA M.2 SSD 32 GB for 25 EUR
This one has MLC memory. I decided to get a M.2 drive, as I run my crunchers without case and cables are always a bit ugly here. And as the price difference compared to a 2.5'' drive was not large...
Transcend STM360 16GB SATA Flash module for 10 EUR
As my second cruncher has no M.2 slot, I first wanted to stick with a USB drive. But then I stumbled upon this one. It has MLC memory, is plugged directly into the SATA port without cable, and most important, it was the last one available and on sale (prices elsewhere were considerably higher)

So all in all I paid a bit more than I would have paid for USB flash drives, but hopefully they will work long enough to compensate for that...

When they arrive I will install Lubuntu 16.04 on them and let them crunch. I will let you know if there is anything noteworthy to say about them...

I run quite the variety of hardware in everyday life. This is what works for me as a professional, with a bit of added perspective...

As for usb drives; one gets what one pays for. Get a ten dollar usb drive; expect it to be of very low capacity, or very low quality, and generally will not last long. A majority of usb drives also cannot take 24/7 operation for long - will end up losing data, or will even have complete failure.

Some of the higher end usb drives are capable of 24/7 operation, are of top quality, and should last almost indefinitely - such as Apricorn. But also typically cost upwards of one hundred each.

If you are looking for a good usb drive try to get one that has both 2.o and 3.xx compatibility. Might also want to strongly weigh getting one that has encryption/security.

The better option for most = SSD. Do not get anything less that 64gig - anything less will not handle much of anything, especially operating systems w/updates such as Windows - although you mentioned you use something besides Windows - a plus.

Then there's old fashioned platter drives. Nothing beats a platter drive for retaining information. Because a usb or an SSD drive can lose every shred of data when it fails - typically a platter drive only loses a small portion. But since they are mechanical - they would not be ideal for use on WCG.

The wattage option... One can find Intel i7 quad or even six core laptops that do run at less than 25watts. Wait another few months, and the Intel i9 should be out for laptops

And even where I/O is concerned, are reads really that damaging? Seems it's the writes that cause the most wear and tear. Hope I can get 1+ years out of this 16 GB Lexar. Fingers crossed.

As this box only runs BOINC, I'm not worried about failure. Rinse and repeat. I got the 3-pack on sale from Costco.

@judson Somerville MD

What is the purpose of the system you would like to build? Because even if money is not an issue, the optimal built depends on the specific purpose.
You mentioned "crunching machine" in your post, do you intend to build something to primarily contribute to WCG?

(this issue is a bit off-topic in this thread, so maybe a mod might want to separate this into a new thread)

Worrying about nand chip's wear? A small tip:

You're using linux, so I assume you can use "mount" command.

If your computer has enough memory, I suggest you mount a small tmpfs to store boinc data and reduce program/erase cycle on your pen drive's nand flash chip.

https://superuser.com/questions/847469/how-to-correctly-mount-a-tmpfs

As wcg does not really occupy much space, 1GiB is fairly enough. But if you want to complete other missions like Rosseta@Home, that's another question.




And, I also have a question:

Why do you all hate hdd's power consumption so much?

Take my Seagate Momentus 5400.2 for example:

marked 5V 0.42A, then 2.1Watt.

24 hours a day, 365 days a year.

computation shows it consumes about 18kWh a year.

Your country field is Germany so I'll count your electricity price as 0.31 Euro per kWh. This means you'll have to pay 5.6 Euro more every year for electricity.

But HDD is quite cheap, and don't tend to broke down for tens of years. If take efforts and money saved by not having to buy another USB pen drive and write the system inside into consideration, I'd give hdd a shot.