Migrating from HDF5 1.6 to 1.8

October 15, 2008 HDF and HDF-EOS Workshop XII 1

Migrating from HDF5 1.6 to HDF5 1.8


Outline

• Status of the HDF5 1.6 and 1.8 releases• Overview of the HDF5 1.8 features• How to move applications to HDF5 1.8 ?

Status of HDF5 releases

October 15, 2008 3HDF and HDF-EOS Workshop XII


Current HDF5 Releases

• HDF5 1.8.0 was released in February 2008• Major update of HDF5 1.6.* series (stable set of

features and APIs since 1998)• New features• 200 new APIs• Changes to file format• Changes to APIs• Backward compatible

• HDF5 1.8.1 was released in June 2008• Minor bug fixes

• Included Fortran90 APIs for new C functions


Current HDF5 Releases

• HDF5 1.6.7 was released in February 2008• Addressed backward compatibility bug for reading

files with corrupted object header information

• New maintenance releases will be in November 2008• HDF5 1.6.8 and 1.8.2

• Minor bug fixes• Tools improvements

• Current plans are to support HDF5 1.6 and 1.8 until November 2009


Information About Current Releases

http://www.hdfgroup.org/HDF5


Goal of the Tutorial

• Help with transition to the 1.8 releases• Discuss new features beneficial to applications

written for 1.6 releases• Raise awareness about forward/backward

compatibility issues with the 1.8 releases• Get feedback from the users who already moved

to 1.8 releases


Why New Features?

• Need to address some deficiencies in initial design• Examples:

• Big overhead in file sizes• Non-tunable metadata cache implementation• Handling of free-space in a file


Why New Features?

• Need to address new requirements• Add support for

• New types of indexing (object creation order)• Big volumes of variable-length data (DNA

sequences)• Simultaneous real-time streams (fast append to one

-dimensional datasets)• UTF-8 encoding for objects’ path names• Accessing objects stored in another HDF5 files

(external or user-defined links)

What Did We Do in HDF5 1.8?

• Extended File Format Specification • Reviewed group implementations• Introduced new link object• Revamped metadata cache implementation• Improved handling of datasets and datatypes• Introduced shared object header message• Extended error handling• Enhanced backward/forward APIs and file format

compatibility


What Did We Do in HDF5 1.8?

And much more good stuff to make HDF5


Better and Faster


HDF5 File Format Extension



• Why: • Address deficiencies of the original file format

• Address space overhead in an HDF5 file

• Enable new features

• What: • New routine that instructs the HDF5 library to

create all objects using the latest version of the HDF5 file format (cmp. with the earliest version when object became available, for example, array datatype)



Example

/* Use the latest version of a file format for each object created in a file */

fapl_id = H5Pcreate(H5P_FILE_ACCESS);H5Pset_libver_bounds(fapl_id, H5F_LIBVER_LATEST, H5F_LIBVER_LATEST);fid = H5Fcreate(…,…,…,fapl_id);orfid = H5Fopen(…,…,fapl_id);


Group Revisions


Better Large Group Storage

• Why: • Faster, more scalable storage and access for large

groups

• What: • New format and method for storing groups with

many links


Informal Benchmark

• Create a file and a group in a file• Create up to 10^6 groups with one dataset in

each group• Compare files sizes and performance of HDF5

1.8.1 using the latest group format with the performance of HDF5 1.8.1 (default, old format) and 1.6.7

• Note: Default 1.8.1 and 1.6.7 became very slow after 700000 groups

Time to Open and Read a Dataset


Time to Close the File


File Size



Access Links by Creation Order

• Why: • Allow iteration and lookup of group’s links

(children) by creation order as well as by name order

• Support NetCDF access model for NetCDF-4

• What: • Option to access objects in group according to

relative creation time


Access Links by Creation Order

Example

/* Track and index creation order of the links */

H5Pset_link_creation_order(gcpl_id, (H5P_CRT_ORDER_TRACKED | H5P_CRT_ORDER_INDEXED));

/* Create a group */

gid = H5Gcreate(fid, GNAME, H5P_DEFAULT, gcpl_id, H5P_DEFAULT);


Example: h5dump --group=1 tordergr.h5

HDF5 "tordergr.h5" {GROUP "1" { GROUP "a" { GROUP "a1" { } GROUP "a2" { GROUP "a21" { } GROUP "a22" { } } } GROUP "b" { } GROUP "c" { …


Example: h5dump --sort_by=creation_order

HDF5 "tordergr.h5" {GROUP "1" { GROUP "c" { } GROUP "b" { } GROUP "a" { GROUP "a1" { } GROUP "a2" { GROUP "a22" { } GROUP "a21" { } } }


Compact Groups

• Why: • Save space and access time for small groups• If groups are small, don’t need B-tree overhead

• What:• Alternate storage for groups with few links• Default storage when “latest format” is specified• Library converts to “original” storage (B-tree based)

using default or user-specified threshold


Compact Groups

• Example• File with 11,600 groups• With original group structure, file size ~ 20 MB• With compact groups, file size ~ 12 MB• Total savings: 8 MB (40%)• Average savings/group: ~700 bytes


Compact Groups

Example

/* Change storage to “dense” if number of group members is bigger than 16 and go back to compact storage if number of group members is smaller than 12 */

H5Pset_link_phase_change(gcpl_id, 16, 12)

/* Create a group */

g_id = H5Gcreate(…,…,…,gcpl_id,…);


Intermediate Group Creation

• Why: • Simplify creation of a series of connected groups

• Avoid having to create each intermediate group separately, one by one

• What: • Intermediate groups can be created when creating

an object in a file, with one function call



• Want to create “/A/B/C/dset1”• “A” exists, but “B/C/dset1” do not

/A

/A

BB

dset1dset1

CC

One call creates groups “B” & “C”, then creates “dset1”



Example

/* Create link creation property list */

lcrp_id = H5Pcreate(H5P_LINK_CREATE);

/* Set flag for intermediate group creation

Groups B and C will be created automatically */

H5Pset_create_intermediate_group(lcrp_id, TRUE);

ds_id = H5Dcreate (file_id, "/A/B/C/dset1",…,…,

lcrp_id,…,…,);

Link Revisions



What are Links?

• Links connect groups to their members• “Hard” links point to a target by address• “Soft” links store the path to a target

root group

Hard link

dataset

Soft link“/target dataset”<address>


Links: Before and After

• New data model for handling links• Links may have properties (UTF-8 name

encoding, creation order indexing, storage property, etc.)

Group

Before After

Group

Object Object

Name Name and other properties


Anonymous Object

• Object can be created without being immediately linked into graph structure• Group, dataset and datatype

• See new H5*create_anon APIs

Group

Object

• Use H5O* APIs to manipulate the objects


New: External Links

• Why:• Access objects stored in other HDF5 files in a

transparent way

• What:• Store location of file and path within that file

• Can link across files


file2.h5

file1.h5

New: External Links

root group

“External_link”

“file2.h5”

“/A/B/C/D/E”

root group

group

“target object”

<address>

External link object “External_link” in file1.h5 points to the group/A/B/C/D/E in file2.h5


External Links

Example

/* Create an external link */

H5Lcreate_external(TARGET_FILE, ”/A/B/C/D/E", source_file_id, ”External_link”, …,…);

/* We will use external link to create a group in a target file */

gr_id = H5Gcreate(source_file_id,”External_link/F”,…,…,…,…);

/* We can access group “External_link/F” in the source file and group “/A/B/C/D/E/F” in the target file */


New: User-defined Links

• Why:• Allow applications to create their own kinds of links and

link operations, such as• Create “hard” external link that finds an object by address• Create link that accesses a URL• Keep track of how often a link is accessed, or other behavior

• What:• Applications can create new kinds of links by supplying

custom callback functions• Can do anything HDF5 hard, soft, or external links do

Traversing an HDF5 File



Traversing HDF5 File

• Why:• Allow applications to iterate through the objects in a

group or visit recursively all objects under a group

• What:• New APIs to traverse a group hierarchy • New APIs to iterate through a group using different

types of indices (name or creation order)• H5Giterate is deprecated in favor of new functions



Example of some new APIs

/* Check if object “A/B” exists in a root group */H5Lexists(file_id, “A/B”, …);

/* Iterate through group members of a root group

using name as an index; this function doesn’t recursively follow links into subgroups */

H5Literate(file_id, H5_INDEX_NAME, H5_ITER_INC, &idx, iter_link_cb, &info);

/* Visit all objects under the root group; this function recursively follow links into subgroups */

H5Lvisit(file_id, H5_INDEX_NAME, H5_ITER_INC, visit_link_cb, &info);



• Things to remember• Never use H5Ldelete in any HDF5 iterate or

visit call back functions• Always close parent object before deleting a

child object

Shared Object Header Messages




• Why: metadata duplicated many times, wasting space

• Example:• You create a file with 10,000 datasets• All use the same datatype and dataspace• HDF5 needs to write this information 10,000 times!

Dataset 1

data 1

datatype

dataspace

Dataset 2

data 2

datatype

dataspace

Dataset 3

data 3

datatype

dataspace



What:• Enable messages to be shared automatically

• HDF5 shares duplicated messages on its own!

Dataset 1

data 1

datatype

dataspace

Dataset 2

data 2


Shared Messages

• Happens automatically• Works with datatypes, dataspaces, attributes, fill

values, and filter pipelines• Saves space if these objects are relatively large• May be faster if HDF5 can cache shared

messages• Drawbacks

• Usually slower than non-shared messages• Adds overhead to the file

• Index for storing shared datatypes• 25 bytes per instance

• Older library versions can’t read files with shared messages


Two Informal Tests

• File with 24 datasets, all with same big datatype• 26,000 bytes normally• 17,000 bytes with shared messages enabled• Saves 375 bytes per dataset

• But, make a bad decision: invoke shared messages but only create one dataset…• 9,000 bytes normally• 12,000 bytes with shared messages enabled• Probably slower when reading and writing, too.

• Moral: shared messages can be a big help, but only in the right situation!


Error Handling


Extendible Error-handling APIs

• Why: Enable application to integrate error reporting with HDF5 library error stack

• What: New error handling API• H5Epush - push major and minor error ID on specified error

stack• H5Eprint – print specified stack• H5Ewalk – walk through specified stack• H5Eclear – clear specified stack• H5Eset_auto – turn error printing on/off for specified stack• H5Eget_auto – return settings for specified stack traversal


Error-handling Programming Model

• Create new class, major and minor error messages• Register messages with the HDF5 library• Manage errors

• Use default or create new error stack • Push error• Print error stack• Close stack


Error-handling Example

#define ERR_CLS_NAME "Error Test"

#define PROG_NAME "Error Program"

#define PROG_VERS "1.0”

……

#define ERR_MAJ_TEST_MSG "Error in test”

#define ERR_MIN_MYFUNC_MSG "Error in my function”

……

/* Initialize error information for application */

ERR_CLS = H5Eregister_class(ERR_CLS_NAME, PROG_NAME, PROG_VERS);

ERR_MAJ_TEST = H5Ecreate_msg(ERR_CLS, H5E_MAJOR, ERR_MAJ_TEST_MSG);

ERR_MIN_MYFUNC = H5Ecreate_msg(ERR_CLS, H5E_MINOR, ERR_MIN_MYFUNC_MSG);

……..

/* Unregister major and minor error, and class handles when done */

H5Eunregister_class(ERR_CLS);



/* This function creates and write a dataset */

static herr_t my_function(hid_t fid)

{

…….

/* Force this function to fail and make it push error */

H5E_BEGIN_TRY {

dataset = H5Dcreate1(FAKE_ID, DSET_NAME, H5T_STD_I32BE, space,

H5P_DEFAULT);

} H5E_END_TRY;

if(dataset < 0) {

H5Epush(H5E_DEFAULT, __FILE__, FUNC_my_function, __LINE__, ERR_CLS, ERR_MAJ_IO, ERR_MIN_CREATE, "H5Dcreate failed");

goto error;

} /* end if */

……



Error Test-DIAG: Error detected in Error Program (1.0) thread 0: #000: error_example.c line 160 in main(): Error stack test failed major: Error in test minor: Error in my function #001: error_example.c line 100 in my_function(): H5Dcreate failed major: Error in IO minor: Error in H5DcreateHDF5-DIAG: Error detected in HDF5 (1.8.1) thread 0: #002: H5Ddeprec.c line 154 in H5Dcreate1(): not a location ID major: Invalid arguments to routine minor: Inappropriate type #003: H5Gloc.c line 241 in H5G_loc(): invalid object ID major: Invalid arguments to routine minor: Bad value


Metadata Cache


Metadata Cache Improvements

• Why: • Improve I/O performance and memory usage when

accessing many objects• What:

• New metadata cache APIs• control cache size• monitor actual cache size and current hit rate

• Under the hood: adaptive cache resizing• Automatically detects the current working size• Sets max cache size to the working set size


Metadata Cache Improvements

• Note: most applications do not need to worry about the cache.

• See “Special topics” in the HDF5 User’s Guide for details.

• And if you do see unusual memory growth or poor performance, please contact us. We want to help you.

Dataset and Datatype Improvements



Text-based Datatype Descriptions

• Why:• Simplify data type creation

• Make data type creation code more readable

• Facilitate debugging by printing the text description of a data type

• What: • New routines to create an HDF5 data type through

the text description of the data type and get a text description from the HDF5 data type


Text Datatype Description

Example

/* Create the data type from DDL text description */dtype = H5LTtext_to_dtype(( "H5T_IEEE_F32BE\n”,H5LT_DDL);"H5T_IEEE_F32BE\n”,H5LT_DDL);

/* Convert the data type back to text */

H5LTtype_to_text(dtype, NULL, H5LT_DLL, str_len);dt_str = (char*)calloc(str_len, sizeof(char));

H5LTdtype_to_text(dtype, dt_str, H5LT_DDL, &str_len);


Serialized Datatypes and Dataspaces

• Why: • Allow datatype and dataspace info to be

transmitted between processes

• Allow datatype/dataspace to be stored in non-HDF5 files

• What: • A new set of routines to serialize/deserialize HDF5

datatypes and dataspaces.


Serialized Datatypes and Dataspaces

Example

/* Find the buffer length and encode a datatype into buffer */

status = H5Tencode(t_id, NULL, &cmpd_buf_size);cmpd_buf = (unsigned char*)calloc(1, cmpd_buf_size);H5Tencode(t_id, cmpd_buf, &cmpd_buf_size)

/* Decode a binary description of a datatype and retune a datatype handle */

t_id = H5Tdecode(cmpd_buf);


Integer to Float Convert During I/O

• Why: • HDF5 1.6 and earlier supported conversion within

the same class (16-bit integer 32-bit integer, 64-bit float 32-bit float)

• Conversion needed to support NetCDF-4 programming model

• What: • Integer to float conversion supported during I/O


Integer to Float Convert During I/O

Example: conversion is transparent to application

/* Create a dataset of 64-bit little-endian type */

dset_id = H5Dcreate(loc_id,“Mydata”, H5T_IEEE_F64LE,space_id, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT);

/* Write integer data to “Mydata” */

status = H5Dwrite(dset_id, H5T_NATIVE_INT, …);


Revised Conversion Exception Handling

• Why: • Give apps greater control over exceptions (range

errors, etc.) during datatype conversion

• Needed to support NetCDF-4 programming model

• What: • Revised conversion exception handling


Revised Conversion Exception Handling

• To handle exceptions during conversions, register handling function through H5Pset_type_conv_cb().

• Cases of exception:• H5T_CONV_EXCEPT_RANGE_HI• H5T_CONV_EXCEPT_RANGE_LOW• H5T_CONV_EXCEPT_TRUNCATE• H5T_CONV_EXCEPT_PRECISION• H5T_CONV_EXCEPT_PINF• H5T_CONV_EXCEPT_NINF• H5T_CONV_EXCEPT_NAN

• Return values: H5T_CONV_ABORT, H5T_CONV_UNHANDLED, H5T_CONV_HANDLED


Compression Filter for N-bit Data

• Why: • Compact storage for user-defined datatypes

• What:• When data stored on disk, padding bits chopped

off and only significant bits stored

• Works with compound datatypes


N-bit Compression Example

• In memory, one value of N-Bit datatype is stored like this:

| byte 3 | byte 2 | byte 1 | byte 0 ||????????|????SPPP|PPPPPPPP|PPPP????|

S-sign bit P-significant bit ?-padding bit

• After passing through the N-Bit filter, all padding bits are chopped off, and the bits are stored on disk like this:

| 1st value | 2nd value ||SPPPPPPP PPPPPPPP|SPPPPPPP PPPPPPPP|...

• Opposite (decompress) when going from disk to memory• Limited to integer and floating-point data


N-bit Compression Example

Example

/* Create a N-bit datatype */

dt_id = H5Tcopy(H5T_STD_I32LE); H5Tset_precision(dt_id, 16); H5Tset_offset(dt_id, 4);

/* Create and write a dataset */

dcpl_id = H5Pcreate(H5P_DATASET_CREATE); H5Pset_chunk(dcpl_id, …); H5Pset_nbit(dcpl_id);dset_id = H5Dcreate(…,…,…,…,…,dcpl_id,…); H5Dwrite(dset_id,…,…,…,…,buf);


Offset+size Storage Filter

• Why:• Use less storage when less precision needed

• What:• Performs scale/offset operation on each value• Truncates result to fewer bits before storing• Currently supports integers and floats• Precision may be lost


Example with Floating-Point Type

• Data: {104.561, 99.459, 100.545, 105.644}• Choose scaling factor: decimal precision to keep

E.g. scale factor D = 21. Find minimum value (offset): 99.4592. Subtract minimum value from each

elementResult: {5.102, 0, 1.086, 6.185}

3. Scale data by multiplying 10D = 100Result: {510.2, 0, 108.6, 618.5}

4. Round the data to integerResult: {510 , 0, 109, 619}

5. Pack and store using min number of bits


Offset+size Storage Filter

Example

/* Use scale+offset filter on integer data; let library figure out the number of minimum bits necessary to story the data without loss of precision */

H5Pset_scaleoffset (dcrp_id,H5Z_SO_INT,H5Z_SO_INT_MINBITS_DEFAULT);

H5Pset_chunk(dcrp_id,…,…);

dset_id = H5Dcreate(…,…,…,…,…,dcpl_id, …);

/* Use sclae+offset filter on floating-point data; compression may be lossy */

H5Pset_scaleoffset(dcrp_id,H5Z_SO_FLOAT_DSCALE,2 );


“NULL” Dataspace

• Why:• Allow datasets with no elements to be described

• NetCDF-4 needed a “place holder” for attributes

• What:• A dataset with no dimensions, no data


NULL Dataspace

Example

/* Create a dataset with “NULL” dataspace*/

sp_id = H5Screate(H5S_NULL);

dset_id = H5Dcreate(…,"SDS.h5”,…,sp_id,…,…,…);

HDF5 "SDS.h5" {GROUP "/" { DATASET "IntArray" { DATATYPE H5T_STD_I32LE DATASPACE NULL DATA { } }}}

Part IIHow to Move an Application

to HDF5 1.8



If you are new to HDF5 …

• Start with the HDF5 Tutorial and use HDF5 1.8.1 (or later) librarieshttp://www.hdfgroup.org/HDF5/Tutor/

• Look at the comprehensive set of exampleshttp://www.hdfgroup.uiuc.edu/UserSupport/examples-by-api/api18-c.html

• Use HDF5 Reference Manual 1.8.1 or laterhttp://www.hdfgroup.org/HDF5/doc

to get the latest APIs

• Use h5cc, h5fc, h5c++ scripts to build your applications

http://www.hdfgroup.org/HDF5/Tutor/

http://www.hdfgroup.uiuc.edu/UserSupport/examples-by-api/api18-c.html

http://www.hdfgroup.uiuc.edu/UserSupport/examples-by-api/api18-c.html

http://www.hdfgroup.org/HDF5/doc



• To check library version • Talk to you system administrator

• Try any HDF5 command line utility with –V flag./h5dump -V

h5dump: Version 1.8.1

• Look at the libhdf5.settings file on your system (under lib directory in the HDF5 installation directory); you should see the following lines

HDF5 Version: 1.8.1

Default API Mapping: v18 (can be v16)

• API mapping indicates API version (1.8 in this case)



• Use the latest version of API from the Reference Manual (for example, H5Gcreate or H5Gcreate2 instead of H5Gcreate1)

• Be aware of forward compatibility issues• If you use HDF5 features introduced in 1.8.0 and

later, you may create a file that old applications and third party tools may not be able to read

http://www.hdfgroup.org/HDF5/doc/ADGuide/CompatFormat180.html

• All HDF5 command line utilities and tools should read HDF5 files created during the last 10 years

• Report problems to [email protected]

http://www.hdfgroup.org/HDF5/doc/ADGuide/CompatFormat180.html

mailto:[email protected]


If you used HDF5 before….

• And would like to switch to 1.8….• Or you build and install HDF5 Libraries for

yourself or others….• You need to know about HDF5 API versioning.

Introduction to HDF5 API Versioning



API Versioning Example

• Old way

H5Gcreate ( loc_id, “New/My old group”, 0 )

H5Gcreate1( loc_id, “New/My old group”, 0 )• No new features can be invoked

• New wayH5Gcreate ( loc_id, “New/My new group”, lcpl_id, gcpl_id, gapl_id)

H5Gcreate2( loc_id, “New/My new group”, lcpl_id, gcpl_id, gapl_id)

• New features can be invoked Creation order Unicode names Compact storage Intermediate group creation

• In 1.8.0 and later some functions have version number suffix.


HDF5 Macros for API Compatibility

Name: H5GcreateSignature: hid_t H5Gcreate( hid_t loc_id, const char *name, size_t

size_hint ) hid_t H5Gcreate( hid_t loc_id, const char *name, hid_t

lcpl_id, hid_t gcpl_id, hid_t gapl_id Purpose: Creates a new empty group and links it to a location in the

file.Description: H5Gcreate is a macro that is mapped to either

H5Gcreate1 or

H5Gcreate2, depending on the needs of the application.


HDF5 Library Configuration

• Mapping of APIs is set at configuration time• Several configuration flags are provided to enable

different mappings• Macro name is mapped to old API, e.g., H5Gcreate

is mapped to H5Gcreate1

• Macro name is mapped to new API, e.g., H5Gcreate is mapped to H5Gcreate2 (will have different parameters from 1.6 H5Gcreate)

• Disable old APIs completely, e.g., H5Gcreate1 is not available in the library


If you are HDF5 library maintainer…

• If you do installation of the HDF5 Library, there are several choices• Install library with 1.8 APIs as default APIs (default,

recommended).

• Install library with 1.6 APIs.

• Install library without 1.6 APIs to get smaller footprint.

• Install library with strict file format checking option to detect files that do not comply with the File Format Specification.


HDF5 Library Configuration

Configure flag Public APIs has version

--with-default-api-version=v18

(default)

1.8(Example: H5Gcreate is mapped to H5Gcreate2, old H5Gcreate is H5Greate1)

--enable-strict-format-checks1.8

Library checks compliance with the file format

--disable-deprecated-symbols

1.8(Example: H5Gcreate is mapped to H5Gcreate2, H5Gcreate1 is not available)

--with-default-api-version=v161.6

(Example: H5Gcreate is mapped to H5Gcreate1, H5Gcreate2 is available)


If you used HDF5 before…

• And want to use new HDF5 1.8 Library with the application written for the older versionsh5cc -DH5_USE_16_API my_program.c

• H5Gcreate is mapped to H5Gcreate1; all three H5Gcreate1, H5Gcreate2 and H5Gcreate can be used

• HDF5 compilation scripts and H5_USE_16_API flag can be used with GNU auto tools to build packages like HDF-EOS5.• The HDF Group runs daily tests for HDF-EOS5

using the latest HDF5 Libraries under development


If you used HDF5 before …

• Other available options:Assuming both deprecated and new symbols areavailable in the library:

h5cc my_program.c• Both H5Gcreate1, H5Gcreate2 and H5Gcreate

may be used•H5Gcreate will have new signature

h5cc -DH5_NO_DEPRECATED_SYMBOLS my_program.c

• Only new symbols are available for application; H5Gcreate is mapped to H5Gcreate2; application may use both, but cannot use H5Gcreate1


Example: --with-default-api-version=v18

hid_t file_id, group_id; /* identifiers */ .../* Open “file.h5” */ file_id = H5Fopen(“file.h5”, H5F_ACC_RDWR, H5P_DEFAULT, H5P_DEFAULT);

/* Create several groups in a file */ grp1_id = H5Gcreate (file_id, ”New/A", H5P_DEAFULT, gcpt, gapt); grp2_id = H5Gcreate1(file_id,"/B",0);… grp3_id = H5Gcreate2(file_id,”New/A", H5P_DEAFULT, gcpt, gapt);


Example: --with-default-api-version=v16


/* Create several groups in a file */ grp1_id = H5Gcreate (file_id, "/A",0);grp2_id = H5Gcreate1(file_id,"/B",0); grp3_id = H5Gcreate2(file_id,”New/C", H5P_DEAFULT, gcpt, gapt);


Example: --disable-deprecated-symbols


/* Create several groups in a file */ grp1_id = H5Gcreate (file_id, ”New/A", H5P_DEAFULT, gcpt, gapt);/* Compilation will fail */ grp2_id = H5Gcreate1(file_id,"/B",0); grp3_id = H5Gcreate2(file_id,”New/A", H5P_DEAFULT, gcpt, gapt);


Thank you!

Questions?

Acknowledgement

• This report is based upon work supported in part by a Cooperative Agreement with the National Aeronautics and Space Administration (NASA) under NASA Awards NNX06AC83A and NNX08AO77A. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Aeronautics and Space Administration.


Migrating from HDF5 1.6 to 1.8

Technology

Transcript of Migrating from HDF5 1.6 to 1.8