# Latest **URL:** https://forum.hdfgroup.org/latest.md [Latest](https://forum.hdfgroup.org/latest.md) · [Categories](https://forum.hdfgroup.org/categories.md) --- ## [Read Before Posting: Welcome to The HDF Forum](https://forum.hdfgroup.org/t/read-before-posting-welcome-to-the-hdf-forum/10930)
**Author:** [@lori.cooper](https://forum.hdfgroup.org/u/lori.cooper)\ **Replies:** 0\ **Last updated:** [March 14, 2023, 3:12pm UTC](https://forum.hdfgroup.org/t/read-before-posting-welcome-to-the-hdf-forum/10930 "2023-03-14T15:12:33Z")
Welcome to The HDF Forum. This forum is maintained by The HDF Group, the developers and maintainers of HDF technologies. It is a community-driven forum first, and HDF Group staff will help find answers to questions on a … --- ## [New Java hdf5 library](https://forum.hdfgroup.org/t/new-java-hdf5-library/13882)
**Author:** [@karl.nicholas](https://forum.hdfgroup.org/u/karl.nicholas)\ **Replies:** 0\ **Last updated:** [October 1, 2026, 9:24am UTC](https://forum.hdfgroup.org/t/new-java-hdf5-library/13882 "2026-10-01T09:24:38Z")
Hi, I wrote a java hdf5 library a while back figured I should share in case it is of interest to anyone. It seems to be in good shape, I was able to read all the NASA Earth satellite HDF5 files for example. Please find a… --- ## [HDF Cloud 1.0.0 Release - HSDS, h5pyd, and hdf5-json](https://forum.hdfgroup.org/t/hdf-cloud-1-0-0-release-hsds-h5pyd-and-hdf5-json/13879)
**Author:** [@mlarson](https://forum.hdfgroup.org/u/mlarson)\ **Replies:** 0\ **Last updated:** [September 17, 2026, 6:07pm UTC](https://forum.hdfgroup.org/t/hdf-cloud-1-0-0-release-hsds-h5pyd-and-hdf5-json/13879 "2026-09-17T18:07:54Z")
The HDF Group is pleased to announce the release of HSDS 1.0.0, alongside h5pyd 1.0.0 and hdf5-json 2.0.0. The three projects now share a single implementation of the HDF5 object model, instead of each maintaining its o… --- ## [HDF4 4.0 Release](https://forum.hdfgroup.org/t/hdf4-4-0-release/13878)
**Author:** [@bmribler](https://forum.hdfgroup.org/u/bmribler)\ **Replies:** 0\ **Last updated:** [September 4, 2026, 10:21pm UTC](https://forum.hdfgroup.org/t/hdf4-4-0-release/13878 "2026-09-04T22:21:16Z")
We have released HDF4 4.0 this week. It is going to be the last official release of the HDF4 library. In this release, we have moved to build with CMake exclusively addressed many memory issues and security vulnerabil… --- ## [Released: the HDF5 safety, security & privacy audit](https://forum.hdfgroup.org/t/released-the-hdf5-safety-security-privacy-audit/13877)
**Author:** [@gheber](https://forum.hdfgroup.org/u/gheber)\ **Replies:** 0\ **Last updated:** [September 2, 2026, 10:27am UTC](https://forum.hdfgroup.org/t/released-the-hdf5-safety-security-privacy-audit/13877 "2026-09-02T10:27:29Z")
We have released HDF5-SHINES-2026-001, the HDF5 Audit Report, by Gerd Heber of The HDF Group and Elena Pourmal of Lifeboat, LLC. The report is a targeted, ecosystem-level technical assessment of safety, security, and pr… --- ## [HDF5 and the Hugging Face incident: facts, safeguards, and your input](https://forum.hdfgroup.org/t/hdf5-and-the-hugging-face-incident-facts-safeguards-and-your-input/13873)
**Author:** [@gheber](https://forum.hdfgroup.org/u/gheber)\ **Replies:** 0\ **Last updated:** [August 23, 2026, 10:55pm UTC](https://forum.hdfgroup.org/t/hdf5-and-the-hugging-face-incident-facts-safeguards-and-your-input/13873 "2026-08-23T22:55:14Z")
The recent intrusion into Hugging Face used an HDF5 capability to disclose files from a production dataset worker. If your application or service processes HDF5 files from users, public repositories, automated pipelines,… --- ## [Concurrent read while writing HDF5 file (without SWMR): intermittent metadata / object header errors — any supported workaround?](https://forum.hdfgroup.org/t/concurrent-read-while-writing-hdf5-file-without-swmr-intermittent-metadata-object-header-errors-any-supported-workaround/13659)
**Author:** [@younesr008](https://forum.hdfgroup.org/u/younesr008)\ **Replies:** 2\ **Last updated:** [August 19, 2026, 11:41pm UTC](https://forum.hdfgroup.org/t/concurrent-read-while-writing-hdf5-file-without-swmr-intermittent-metadata-object-header-errors-any-supported-workaround/13659 "2026-08-19T23:41:02Z")
Hello I am trying to read an HDF5 file while it is being written by another process, without using SWMR mode. I understand that this may not be officially supported, but I would like to understand whether there is any s… --- ## [Build tests failing on HDF5-2.2.0 for aarch64](https://forum.hdfgroup.org/t/build-tests-failing-on-hdf5-2-2-0-for-aarch64/13863)
**Author:** [@lwilbert](https://forum.hdfgroup.org/u/lwilbert)\ **Replies:** 1\ **Last updated:** [August 7, 2026, 5:29pm UTC](https://forum.hdfgroup.org/t/build-tests-failing-on-hdf5-2-2-0-for-aarch64/13863 "2026-08-07T17:29:12Z")
I’m attempting to build hdf5-2.2.0 on aarch64 Ubuntu 24.04.4, but the build fails when running some of the tests. What I’ve done: Downloaded the .tar.gz from Github (hdf5-2.2.0.tar.gz) As root, untarred into a directo… --- ## [Release of HDF5 2.2.0 (Newsletter #210)](https://forum.hdfgroup.org/t/release-of-hdf5-2-2-0-newsletter-210/13861)
**Author:** [@gheber](https://forum.hdfgroup.org/u/gheber)\ **Replies:** 0\ **Last updated:** [July 30, 2026, 9:21pm UTC](https://forum.hdfgroup.org/t/release-of-hdf5-2-2-0-newsletter-210/13861 "2026-07-30T21:21:14Z")
The HDF Group is pleased to announce the release of HDF5 2.2.0, delivering improved cloud performance, stronger security capabilities, enhanced build and deployment workflows, and numerous reliability and usability impro… --- ## [Help shape HDF5 safety, security, and privacy: FOSSY Aug 6 + SHINES workshop Aug 12](https://forum.hdfgroup.org/t/help-shape-hdf5-safety-security-and-privacy-fossy-aug-6-shines-workshop-aug-12/13849)
**Author:** [@gheber](https://forum.hdfgroup.org/u/gheber)\ **Replies:** 4\ **Last updated:** [July 29, 2026, 6:19pm UTC](https://forum.hdfgroup.org/t/help-shape-hdf5-safety-security-and-privacy-fossy-aug-6-shines-workshop-aug-12/13849 "2026-07-29T18:19:15Z")
:mega: Help shape the future of HDF5 safety, security, and privacy. Two August events will focus on making HDF5 more transparent, inspectable, and secure: FOSSY 2026 — Aug 6, Vancouver: A GNU poke-based, machine-reada… --- ## [Netcdf complains about hdf5/2](https://forum.hdfgroup.org/t/netcdf-complains-about-hdf5-2/13852)
**Author:** [@eijkhout](https://forum.hdfgroup.org/u/eijkhout)\ **Replies:** 5\ **Last updated:** [July 20, 2026, 7:50pm UTC](https://forum.hdfgroup.org/t/netcdf-complains-about-hdf5-2/13852 "2026-07-20T19:50:31Z")
I’m using essentially the same script for hdf5 version 1.14 and 2.whatever. But netcdf is happy with 1.14 and not with 2: -- Found HDF5: hdf5-shared (found version "2.0.0") found components: C HL -- Found HDF5 version: … --- ## [New vs Old Documentation URLs](https://forum.hdfgroup.org/t/new-vs-old-documentation-urls/9802)
**Author:** [@kittisopikulm](https://forum.hdfgroup.org/u/kittisopikulm)\ **Replies:** 10\ **Last updated:** [July 17, 2026, 9:14pm UTC](https://forum.hdfgroup.org/t/new-vs-old-documentation-urls/9802 "2026-07-17T21:14:33Z")
The portal.hdgroup.org URLs have a nice feature in that they encode the name of the function n the URL: https://portal.hdfgroup.org/display/HDF5/H5D\_CLOSE The new docs.hdfgroup.org URLs use numbered “title” anchors. h… --- ## [Older releases availability](https://forum.hdfgroup.org/t/older-releases-availability/13845)
**Author:** [@martin.raedel](https://forum.hdfgroup.org/u/martin.raedel)\ **Replies:** 1\ **Last updated:** [July 7, 2026, 3:49pm UTC](https://forum.hdfgroup.org/t/older-releases-availability/13845 "2026-07-07T15:49:43Z")
Hi, I have a dependency on HDFView or more precisely the Java HDF Object package in my code. I wanted to update to the current version of HDFView and the object package. Before that, I wanted to make sure that I could ro… --- ## [Save the Date: HDF5 SHINES Workshop at SSDBM 2026 — August 12, San Diego and Online](https://forum.hdfgroup.org/t/save-the-date-hdf5-shines-workshop-at-ssdbm-2026-august-12-san-diego-and-online/13843)
**Author:** [@gheber](https://forum.hdfgroup.org/u/gheber)\ **Replies:** 1\ **Last updated:** [July 2, 2026, 10:34am UTC](https://forum.hdfgroup.org/t/save-the-date-hdf5-shines-workshop-at-ssdbm-2026-august-12-san-diego-and-online/13843 "2026-07-02T10:34:41Z")
The HDF5 SHINES project invites the HDF5 community to a half-day workshop focused on strengthening the safety, security, and privacy of the HDF5 open-source ecosystem. Date: Wednesday, August 12, 2026 Time: 1:00–4:30 p… --- ## [\[OBSOLETE\] HDF5 Working Group meeting](https://forum.hdfgroup.org/t/obsolete-hdf5-working-group-meeting/12282)
**Author:** [@derobins](https://forum.hdfgroup.org/u/derobins)\ **Replies:** 3\ **Last updated:** [July 1, 2026, 5:36pm UTC](https://forum.hdfgroup.org/t/obsolete-hdf5-working-group-meeting/12282 "2026-07-01T17:36:54Z")
The HDF5 Working Group meets weekly, on Thursdays at 10 am Central time. This meeting is for HDF5 library developers and anyone is welcome to attend. The purpose of this meeting is to discuss HDF5 library development. It… --- ## [Schedule Update: HDF5 Working Group Meetings](https://forum.hdfgroup.org/t/schedule-update-hdf5-working-group-meetings/13844)
**Author:** [@brtnfld](https://forum.hdfgroup.org/u/brtnfld)\ **Replies:** 0\ **Last updated:** [July 1, 2026, 5:29pm UTC](https://forum.hdfgroup.org/t/schedule-update-hdf5-working-group-meetings/13844 "2026-07-01T17:29:20Z")
Hello everyone, We are sharing the recurring schedule for the HDF5 Working Group meetings. These meetings will take place on the first Thursday of each month. However, please note that if no agenda items are submitted … --- ## [Error when attempting to view dataset](https://forum.hdfgroup.org/t/error-when-attempting-to-view-dataset/13838)
**Author:** [@trenton.j.rehberger](https://forum.hdfgroup.org/u/trenton.j.rehberger)\ **Replies:** 2\ **Last updated:** [June 24, 2026, 7:49pm UTC](https://forum.hdfgroup.org/t/error-when-attempting-to-view-dataset/13838 "2026-06-24T19:49:39Z")
Hi, I am using HDFView 3.4.1 on Windows 11 installed using the provided .msi file. When I try to open some datasets in my files with it an error box appears which says “An error occurred while loading data for the table:… --- ## [C++ equivalence of Python code for HDF5. Working with datasets resizing, working with indexes \[i\]\[j\] in array-like structures, etc](https://forum.hdfgroup.org/t/c-equivalence-of-python-code-for-hdf5-working-with-datasets-resizing-working-with-indexes-i-j-in-array-like-structures-etc/13836)
**Author:** [@mlt.2](https://forum.hdfgroup.org/u/mlt.2)\ **Replies:** 8\ **Last updated:** [June 22, 2026, 9:16pm UTC](https://forum.hdfgroup.org/t/c-equivalence-of-python-code-for-hdf5-working-with-datasets-resizing-working-with-indexes-i-j-in-array-like-structures-etc/13836 "2026-06-22T21:16:30Z")
This post is about code conversion from Python to C++ about HDF5, trying to keep the C++ part simplified, and this about a specific part from a previous post here, just in order to separate that whole content in separate… --- ## [Use C preprocessor macros (e.g. version numbers) in Fortran](https://forum.hdfgroup.org/t/use-c-preprocessor-macros-e-g-version-numbers-in-fortran/7298)
**Author:** [@jonathan.schilling](https://forum.hdfgroup.org/u/jonathan.schilling)\ **Replies:** 6\ **Last updated:** [June 19, 2026, 2:16pm UTC](https://forum.hdfgroup.org/t/use-c-preprocessor-macros-e-g-version-numbers-in-fortran/7298 "2026-06-19T14:16:22Z")
Hi there, I am currently working on a Fortran codebase, which uses HDF5 as output file format. The code runs on various machines, from laptops to supercomputers (hence many different compilers, versions of HDF5 etc.). T… --- ## [Hdf5 on Rust as a Cargo crate](https://forum.hdfgroup.org/t/hdf5-on-rust-as-a-cargo-crate/12725)
**Author:** [@lrossi](https://forum.hdfgroup.org/u/lrossi)\ **Replies:** 12\ **Last updated:** [June 18, 2026, 2:14pm UTC](https://forum.hdfgroup.org/t/hdf5-on-rust-as-a-cargo-crate/12725 "2026-06-18T14:14:47Z")
Hi all, I would really love to use hdf5 in my rust codebase but I’m a bit concerned. the most used wrapper that I know of is this one: hdf5 - Rust but it is not getting updates (does not even work with the latest vers… --- ## [C++ equivalence of Python code for HDF5. Is possible to write 2d std::vector to HDF5 file similarly to 2d std::array? or more simplified in general](https://forum.hdfgroup.org/t/c-equivalence-of-python-code-for-hdf5-is-possible-to-write-2d-std-vector-to-hdf5-file-similarly-to-2d-std-array-or-more-simplified-in-general/13832)
**Author:** [@mlt.2](https://forum.hdfgroup.org/u/mlt.2)\ **Replies:** 4\ **Last updated:** [June 16, 2026, 5:12pm UTC](https://forum.hdfgroup.org/t/c-equivalence-of-python-code-for-hdf5-is-possible-to-write-2d-std-vector-to-hdf5-file-similarly-to-2d-std-array-or-more-simplified-in-general/13832 "2026-06-16T17:12:56Z")
This post is about code conversion from Python to C++ about HDF5, trying to keep the C++ part simplified. General process in the program about HDF5: Generate a .h5 file with one or more datasets. Writing/reading if th… --- ## [Unable to make HDF5 and HDFView work, both at the same time, neither with the .msi HDF5 installation nor with the vcpkg HDF5 installation](https://forum.hdfgroup.org/t/unable-to-make-hdf5-and-hdfview-work-both-at-the-same-time-neither-with-the-msi-hdf5-installation-nor-with-the-vcpkg-hdf5-installation/13824)
**Author:** [@mlt.2](https://forum.hdfgroup.org/u/mlt.2)\ **Replies:** 4\ **Last updated:** [June 15, 2026, 7:23pm UTC](https://forum.hdfgroup.org/t/unable-to-make-hdf5-and-hdfview-work-both-at-the-same-time-neither-with-the-msi-hdf5-installation-nor-with-the-vcpkg-hdf5-installation/13824 "2026-06-15T19:23:56Z")
I’m trying to work with HDF5 in a cpp program and at the same time also with HDFView (v3.4.1, currently the most recent version). I’m new with HDF5 and currently I’m trying to work with the next program example: h5tutr… --- ## [Explainer on outcome of "page\_buf\_size" value](https://forum.hdfgroup.org/t/explainer-on-outcome-of-page-buf-size-value/13809)
**Author:** [@carroll.ian](https://forum.hdfgroup.org/u/carroll.ian)\ **Replies:** 3\ **Last updated:** [June 8, 2026, 2:19pm UTC](https://forum.hdfgroup.org/t/explainer-on-outcome-of-page-buf-size-value/13809 "2026-06-08T14:19:16Z")
The h5py.File argument page\_buf\_size is confusing me, and since there’s a lot of enthusiasm for cloud-optimization of HDF5 files, I thought asking for a brief public explainer would be useful. The docs say the value “mu… --- ## [\[UPDATE to the Update\]\[Discontinued\]: Change in "Call the Doctor" Meeting Schedule](https://forum.hdfgroup.org/t/update-to-the-update-discontinued-change-in-call-the-doctor-meeting-schedule/13810)
**Author:** [@brtnfld](https://forum.hdfgroup.org/u/brtnfld)\ **Replies:** 1\ **Last updated:** [June 5, 2026, 7:42pm UTC](https://forum.hdfgroup.org/t/update-to-the-update-discontinued-change-in-call-the-doctor-meeting-schedule/13810 "2026-06-05T19:42:26Z")
Hi everyone, We are updating the schedule for our “Call the Doctor” meetings. The frequency will change from weekly to every other week (bi-weekly). What is changing? Current Schedule: Weekly on Tuesdays, 12:20 PM, C… --- ## [Need clarification of how to read variable length strings in C code](https://forum.hdfgroup.org/t/need-clarification-of-how-to-read-variable-length-strings-in-c-code/13814)
**Author:** [@shawn.fox](https://forum.hdfgroup.org/u/shawn.fox)\ **Replies:** 1\ **Last updated:** [June 3, 2026, 12:01pm UTC](https://forum.hdfgroup.org/t/need-clarification-of-how-to-read-variable-length-strings-in-c-code/13814 "2026-06-03T12:01:40Z")
Looking at the H5Dread API, it isn’t clear to me whether the caller should allocate the memory of the buffer. It only shows one example for a data type of integer and the caller does create the memory buffer before makin… --- ## [Building HDF5 with Fortran](https://forum.hdfgroup.org/t/building-hdf5-with-fortran/13802)
**Author:** [@mikez](https://forum.hdfgroup.org/u/mikez)\ **Replies:** 1\ **Last updated:** [June 2, 2026, 2:35pm UTC](https://forum.hdfgroup.org/t/building-hdf5-with-fortran/13802 "2026-06-02T14:35:09Z")
Trying to build HDF5 libraries with Fortran support for VASP using Intel MPI. It doesn’t seem to be creating the .mod files even though I’m using -DHDF5\_BUILD\_FORTRAN:BOOL=ON in CMAKE. tried using .tgz and git source c… --- ## [HDF5 binary difference](https://forum.hdfgroup.org/t/hdf5-binary-difference/13709)
**Author:** [@julie](https://forum.hdfgroup.org/u/julie)\ **Replies:** 14\ **Last updated:** [May 29, 2026, 5:42pm UTC](https://forum.hdfgroup.org/t/hdf5-binary-difference/13709 "2026-05-29T17:42:22Z")
I created a conversion application for a client using the HDF5 libraries. This application was working fine for them as of late 2024. I made some updates in 2025. It worked well on my desktop and I was able to convert th… --- ## [RFC: Internal Multithreading for Chunk I/O](https://forum.hdfgroup.org/t/rfc-internal-multithreading-for-chunk-i-o/13808)
**Author:** [@nfortne2](https://forum.hdfgroup.org/u/nfortne2)\ **Replies:** 0\ **Last updated:** [May 28, 2026, 9:11pm UTC](https://forum.hdfgroup.org/t/rfc-internal-multithreading-for-chunk-i-o/13808 "2026-05-28T21:11:49Z")
Here is an RFC describing a new feature we’re developing that will accelerate chunked I/O by internally splitting the operation into multiple threads, with each thread handling one chunk (or more than one if there are mo… --- ## [Learn about the Column-Oriented Storage Layout for HDF5 (HEP001) – Aleksandar Jelenak – Call the Doctor 5/19/26](https://forum.hdfgroup.org/t/learn-about-the-column-oriented-storage-layout-for-hdf5-hep001-aleksandar-jelenak-call-the-doctor-5-19-26/13796)
**Author:** [@lori.cooper](https://forum.hdfgroup.org/u/lori.cooper)\ **Replies:** 1\ **Last updated:** [May 28, 2026, 5:08pm UTC](https://forum.hdfgroup.org/t/learn-about-the-column-oriented-storage-layout-for-hdf5-hep001-aleksandar-jelenak-call-the-doctor-5-19-26/13796 "2026-05-28T17:08:15Z")
Learn about the Column-Oriented Storage Layout for HDF5 (HEP001) – Aleksandar Jelenak – Call the Doctor 5/19/26 Join us for our next Call the Doctor session on Tuesday, May 19, 2026, at 12:20 p.m. CT, featuring Aleksanda… --- ## [H5Datatype with variable length: How to set the values?](https://forum.hdfgroup.org/t/h5datatype-with-variable-length-how-to-set-the-values/9162)
**Author:** [@martin.raedel](https://forum.hdfgroup.org/u/martin.raedel)\ **Replies:** 16\ **Last updated:** [May 27, 2026, 3:10pm UTC](https://forum.hdfgroup.org/t/h5datatype-with-variable-length-how-to-set-the-values/9162 "2026-05-27T15:10:00Z")
Hi, i am trying create a compound dataset that uses variable length data as shown in the last 2 columns here: For testing I tried to create a simple compound dataset having only one “column” of variable length 32-bit… [Next page](https://forum.hdfgroup.org/latest.md?page=1)