Dear All, I am trying to build a merger tree of halos over a time series with MergerTree() using the following code. *from yt.mods import *from yt.analysis_modules.halo_merger_tree.api import *from yt.analysis_modules.halo_finding.api import *import sqlite3files = []start = 10finish = 58for i in range(start, finish + 1): files.append('/data1/pdf/csurajit/cosmo-sim_1/RD%04d/RedshiftOutput%04d' % (i, i))MergerTree(restart_files=files, database='/data1/pdf/csurajit/cosmo-sim_1/halos/halos.db', halo_finder_function=parallelHF)* But I am getting the following error Traceback (most recent call last): File "halo_db.py", line 11, in <module> MergerTree(restart_files=files, database='/data1/pdf/csurajit/cosmo-sim_1/halos/halos.db', halo_finder_function=parallelHF) File "/home/pdf/csurajit/yt-x86_64/src/yt-hg/yt/analysis_modules/halo_merger_tree/merger_tree.py", line 190, in __init__ self._run_halo_finder_add_to_db() File "/home/pdf/csurajit/yt-x86_64/src/yt-hg/yt/analysis_modules/halo_merger_tree/merger_tree.py", line 270, in _run_halo_finder_add_to_db self.cursor.execute(line) sqlite3.OperationalError: disk I/O error What may be the problem? Thank You.. -- Reju Sam John