Hi @lijiang,
Since you’ve got more information here than in the othrer thread, I’ve closed that one off, though much of my suggestions there still apply. But please don’t generate duplicate threads; it won’t actually reduce the time taken for a response.
I presume that /media/mcair_store/ definitely corresponds to the disk with 64TB free? If you’d instructed MRtrix3 to make the script’s scratch directory in /tmp, I could foresee it being a storage space issue, but that doesn’t seem to be the case.
In part this question relates to the “Permission denied” error message. This isn’t wholly generated by MRtrix3, it’s generated by the system and MRtrix3 simply echoes it up to the terminal; and sometimes with deep system messages like this they can be erroneously specific.
You could also try monitoring disk & RAM usage while the script is executing to see if anything is maxxing out. Though given the scratch directory is retained after the failure, the available disk space would be expected to be zero at that point.
There’s nothing particularly special about the number 24, I would not expect it to be a programming limitation of some sort. So beyond that I’m out of ideas.
Rob