Exact same WU folds on 2 servers.

[-alias-]

Getting the exact same WU on 2 servers should as far as enlightened me on this forum, not be possible, but it is!

This has also happened to me before, especially often when GPU folding. Can someone explain to me how this is possible?

[Joe_H]

It happens occasionally. As long as each server had F@H installed separately, i.e. not a clone of another install, then each server should have an unique machine ID assigned by PG the first time the client connects to the servers. Usually the only time a WU is sent out more than once is after the return of a failed WU, then the usual procedure is that it gets sent out to two different machines to verify whether the WU was bad or not. Usually the two assignments got to different folders, but it appears that only different machine ID's are used to determine who gets them. By chance it can be the same folder.

Since the GPU projects and cores are in active development, and with the recent problems with running on Maxwell based cards and the recent drivers, this may be more common than on CPU WU's. However, there have been a few posts in the past by folders surprised to find they had two different machines working on the same WU. They have not been frequent though.

The reason I mentioned the problem with cloned installs of F@H is that can lead to two machines with the same ID. If they request a WU close enough in time, the servers can interpret the second request as a retry of a download made by the first to download.

[-alias-]

Thanks, but just to have underlined the fact, that this is two different machines with two different installations made ​​with several months between the installations, meaning unique machine ID. I have folded 94537 WU`s and this have as far as I remember happened to me 6-7 times before but this is the first time with SMP units as I can remember.

Then my guess is that this is the reason, as you wrote here: "Usually the only time a WU is sent out more than once is after the return of a failed WU, then the usual procedure is that it gets sent out to two different machines to verify whether the WU was bad or not."

So my final question is, do I get credit for both WU`s?

[EXT64]

I am pretty sure you will (or should at least) as these were clearly two separate assigns of the same WU.

[7im]

As explained previously, yes, you will get credit for both.

[bruce]

You say this has happened before. Did you get credit for the same WU then? If you do NOT get credit this time, let us know. Although Cloning is the only known reason for a duplicate ID, you might be the victim of some extremely unlikely scenario.

You probably would have noticed, though since your production would be greatly reduced and you would have had messages about WUs being rejected as duplications.

[-alias-]

The credit was given correct this time! It is some time since last time (my gpu-folding days 3 - 4 years ago), and I do not recall if / that credit was given then, most likely not, since I dimly remember that there was a discussion around it. Anyway, it does not matter today.