Lustre 1.6 Operations Manual

19.3.3 PIOS Parameters
PIOS has five basic parameters to determine the amount of data that is being
written.
ChunkSize(c):
Amount of data that a thread writes in one attempt. ChunkSize should be a
multiple of filesystem block size.
RegionSize(s):
Amount of data required to fill up a region. PIOS writes a chunksize of data
continuously until it fills the regionsize. RegionSize should be a multiple of
ChunkSize.
RegionCount(n):
Number of regions to write in one or multiple files. The total amount of data written
by PIOS is RegionSize x RegionCount.
ThreadCount(t):
Number of threads working on regions.
Chapter 19 Lustre I/O Kit 19-13