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authorRichard Warren <Richard.Warren@hdfgroup.org>2019-02-18 19:49:35 (GMT)
committerLarry Knox <lrknox@hdfgroup.org>2019-02-18 20:35:01 (GMT)
commit0712f746e900a461513d8f31ddec74d684bd30c8 (patch)
tree2a86c9bf0040ef812202cc77569e292b1a6a5ea2 /release_docs
parenta4b254a92f65b83e344029b60e249b7dcf3cd67c (diff)
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Merge pull request #1560 in HDFFV/hdf5 from hdf5-1-10-documentation-only to hdf5_1_10_5
* commit '5dd2fda18fbbeab95ba44200e48c8202dae65206': Modify RELEASE.txt in response to PR comments Updated RELEASE.txt with updates regarding HDFFV-10540
Diffstat (limited to 'release_docs')
-rw-r--r--release_docs/RELEASE.txt20
1 files changed, 19 insertions, 1 deletions
diff --git a/release_docs/RELEASE.txt b/release_docs/RELEASE.txt
index b5ea8eb..353d63b 100644
--- a/release_docs/RELEASE.txt
+++ b/release_docs/RELEASE.txt
@@ -201,7 +201,7 @@ New Features
-----------------
- Changed the default behavior in parallel when reading the same dataset in its entirely
(i.e. H5S_ALL dataset selection) which is being read by all the processes collectively.
- The dataset mush be contiguous, less than 2GB, and of an atomic datatype.
+ The dataset must be contiguous, less than 2GB, and of an atomic datatype.
The new behavior is the HDF5 library will use an MPI_Bcast to pass the data read from
the disk by the root process to the remain processes in the MPI communicator associated
with the HDF5 file.
@@ -695,6 +695,24 @@ Known Problems
CPP ptable test fails on VS2017 with Intel compiler, JIRA issue: HDFFV-10628.
This test will pass with VS2015 with Intel compiler.
+ Older MPI libraries such as OpenMPI 2.0.1 and MPICH 2.1.5 were tested
+ while attempting to resolve the Jira issue: HDFFV-10540.
+ The known problems of reading or writing > 2GBs when using MPI-2 was
+ partially resolved with the MPICH library. The proposed support recognizes
+ IO operations > 2GB and if the datatype is not a derived type, the library
+ breaks the IO into chunks which can be input or output with the existing
+ MPI 2 limitations, i.e. size reporting and function API size/count
+ arguments are restricted to be 32 bit integers. For derived types larger
+ than 2GB, MPICH 2.1.5 fails while attempting to read or write data.
+ OpenMPI in contrast, implements MPI-3 APIs even in the older releases
+ and thus does not suffer from the 32 bit size limitation described here.
+ OpenMPI releases prior to v3.1.3 appear to have other datatype issues however,
+ e.g. within a single parallel test (testphdf5) the subtests (cdsetr, eidsetr)
+ report data verfication errors before eventually aborting.
+ The most recent versions of OpenMPI (v3.1.3 or newer) have evidently
+ resolved these isses and parallel HDF5 testing does not currently report
+ errors though occasional hangs have been observed.
+
Known problems in previous releases can be found in the HISTORY*.txt files
in the HDF5 source. Please report any new problems found to
help@hdfgroup.org.