Rational ClearCase on the UNIX system and Linux

The following issues are common to most or all variants of the UNIX system and Linux on which Rational® ClearCase® runs.

Limitations of native file backup and copy programs can affect VOB backup and copy operations

Before using native utilities such as tar and cpio to back up or copy VOBs, you must verify that the utility you are using can copy all of the files in the VOB database, regardless of how many there are or how large the largest file is. This is especially important for VOBs at schema version 54, feature level 5, or both.

Establishing the time zone

When establishing the time zone on a host, you must you must specify a full POSIX value for the TZ environment variable. For example:

TZ=EST5DST4,M410/02:00:00,M1050/02:00:00

If you do not, the Rational ClearCase scheduler will not work as designed during transitions into and out of daylight time. On hosts that support the zoneinfo library, you can use zoneinfo to establish the time zone correctly. For more information about the TZ environment variable and the values it can take, see the environ(5) man page for your host operating system.

Shared libraries

IBM Rational ClearCase is implemented through a set of shared libraries. In addition, two shared libraries are supplied from vendors in ccase-home-dir/shlib (where ccase-home-dir is your installation directory, /opt/rational/clearcase by default). The libraries are the C++ compiler library libC.so or libC.sl (depending on vendor; other possible shared C compiler library names follow the pattern libCstring.so, where string may be any short character string), and the EZ-RPC run-time library libezrpc.so (.sl). If the Rational ClearCase libraries in the ccase-home-dir/shlib directory are missing, the Rational ClearCase executables do not run.

Installing in a nondefault installation directory

If you install Rational ClearCase software in a nondefault location (that is, other than in /opt/rational/clearcase), you must set the proper platform-dependent library search-path environment variable to include the ccase-home-dir/shlib pathname so that Rational ClearCase executables can find the required shared libraries.

The order of the pathnames in the environment variable is important. At run time, an executable must find the supplied vendor libraries before it finds any other versions of those libraries in other paths in the list. Other applications that use this definition of the library search-path environment variable may find these supplied vendor libraries instead of other versions of those libraries installed on your system. This behavior may or may not be compatible with those applications. If the supplied vendor libraries are missing, the executables may search the system libraries (the order of search, where it searches, and whether it searches is platform dependent). If a library of the appropriate name is found, the execution may not succeed because the library found may not be compatible with the Rational ClearCase executable.

The following table indicates the search-path environment variable that you need to define to allow Rational ClearCase executables to find their shared libraries. To find the architecture mnemonic associated with your platform, see the sections dealing with individual platforms.

Architecture Mnemonic: Search-Path Environment-Variable Names
sun5: LD_LIBRARY_PATH
linux_ppc, linux_x86, linux_390: LD_LIBRARY_PATH
hp11_pa, hp11_ia64: SHLIB_PATH
aix4_power: LIBPATH

Note: The aix4_power mnemonic covers all AIX platforms. On AIX, if LIBPATH contains any pathnames, it must also include ccase-home-dir/shlib.

xclearcase preferences can cause invalid memory allocation

When Group by Config Spec Rule or Group by Type is set in xclearcase preferences (by using the GUI or by editing the .xclearcase file), and its column is not visible in the xclearcase display, the display is not refreshed correctly after a checkin or checkout. As a result, an incorrect number of selected cells is reported, which can cause invalid memory allocation.

Platform compatibility with clearmake

You can run clearmake in compatibility modes that support certain platform-specific features of make. For more information, see IBM Rational ClearCase Guide to Building Software.

The lock manager

Rational ClearCase 7.0 and later versions no longer run a lock manager process on the UNIX system and Linux. Database access for each VOB on a VOB server is now handled by the VOB's db_server process. This enables you to configure different database parameters for each VOB on your VOB server, which will allow your VOB server to accommodate more VOBs and users. To set default database parameters that apply to all VOBs on your server, configure the vob_almd_params file that is located in /opt/rational/clearcase/config/vob/db. You can override these default settings for individual VOBs by configuring each VOB's vob_almd_params file, which is located in VOB-storage-dir/db/vob_almd_params. The syntax used in this file is as follows:

LOCKMGR_OPTS = -u num -q num

For more information about how to set the -u and -q parameters, see the IBM Rational ClearCase Administrator's Guide.

Note: When you upgrade your VOB server to Rational ClearCase 7.0, lock manager parameters that were set in earlier versions will not be preserved. To preserve your existing VOB database settings, save a copy of your VOB server's /var/adm/rational/clearcase/config/lockmgr.conf before you upgrade Rational ClearCase. After your upgrade is complete, you can copy these settings into the vob_almd_params file as described above.

Issues relevant to specific platforms are discussed in the following topics: