From: "Rob Latham" <[email protected]>

How did this single rank get a negative offset? Was there some integer math that overflowed?

That's for the app developer to figure out. My issue is that if all ranks had failed the write he probably would have started figuring that out a few days ago and I wouldn't have gotten involved :) It's the weird hw error that dragged me into this when the non-failing ranks entered allreduce in romio and the failing ranks entered allreduce in the app. Like I said :

...

Just wondering if there's something I can fix here in addition to the application.

Not the highest priority really. But I coincidentally just got another report (from ANL this time) that an app is hung with half the ranks in write_at_all and half the ranks in a later barrier. It could be something similar. I don't have enough information yet to know but I've suggested they look at errors from write.