[LU-6545] MPIIO short reads

• Type: Bug
• Resolution: Duplicate
• Priority: Critical
• Affects Version/s: Lustre 2.4.3
• Environment: Client: 2.4.3; server: 2.4.3
• Severity: 3
• Assignee: Zhenyu Xu
• Reporter: Mahmoud Hanafi

Description

One of our filesystem is experiencing, what we guess are, short reads that results in NaNs using mpiio function call 'MPI_FILE_READ_AT_ALL'

This can be reproduced every time if the data is read from disk and not cache. So doing a echo 1 > /proc/sys/vm/drop_caches then running the code will error every time, but running the code a second or third time will not produce the error.

NOTE:
This occurs only when the file is striped >1 ost.
In the debug logs the datafile has a fid of [0x2000b2ebc:0x358:0x0]
During the debugging I disabled read ahead

I have captured a full debug trace of lustre on the client and will upload to tftp site.

Issue Links

• is related to: LU-6389 read()/write() returning less than available bytes intermittently