So I have a few theories. I have now had 3 different USB sticks fail on me: Two Sandisk 4GB SDCZ33 and one cheap generic 8GB replacement.
The power draw of the TP-Link system + USB is probably more than the opportunistic USB ports they get plugged in to. An underpowered probe runs great MOST of the time, but a flash bit write is probably the highest power strain and Flash can get really unhappy with power interrupts, based on this SSD research: https://www.usenix.org/system/files/conference/fast13/fast13-final80.pdf I usually use a 500mA or 800mA supply, or tap a nearby router USB port in that range. I suspect the system may demand 1200mA or more. When most flash sticks get errored out enough, they permanently fail into a read only mode, or become fully unreadable. Read-only mode can be reset on some models, but it is not recommended by the vendor. At least one of the failed SANdisk units I had was stuck in a read-only mode. Also, probes may be subjected to ungraceful power down situations, depending on where they are stationed. That can also be a flash drive killer. I don't think we are hitting the write limits of the sticks. I suspect the units are often in underpowered or ungraceful pwoer-down situations, or the USB flash itself is not responding gracefully to poweroff situations. I don't suppose RIPE buys enough USB sticks to get to talk to engineers at SanDISK? I know the newer Raspberry Pi will report when it is in an underpowered situation. Can the TP-Link detect and warn when underpowered? What is the minimum power recommended for TP-Link + USB? Also, are there any USB sticks that have lower power needs and are more robust in low power IoT situations? Is anyone trying to post-mortem the failed sticks? On Fri, May 20, 2016 at 10:03 AM, Gert Doering <g...@space.net> wrote: > Hi, > > On Fri, May 20, 2016 at 04:10:47PM +0200, Philip Homburg wrote: > > We have no clear idea why they fail. It seems that time to failure is > > highly variable. > > Can you correlate tests-until-failure or data-written-until-failure? > > One of mine has failed at least two times now, and it could be that > people just *love* to run tests from 3320... > > My gen 1 probe in 5539 has never had *any* issues. > > gert > -- > have you enabled IPv6 on something today...? > > SpaceNet AG Vorstand: Sebastian v. Bomhard > Joseph-Dollinger-Bogen 14 Aufsichtsratsvors.: A. Grundner-Culemann > D-80807 Muenchen HRB: 136055 (AG Muenchen) > Tel: +49 (0)89/32356-444 USt-IdNr.: DE813185279 >
