Configuring database locking parameters on hosts running the UNIX system and most versions of Linux.

As of Rational® ClearCase® release 7.0.1, the lock manager process has been eliminated on hosts running the UNIX system and most versions of Linux. On those hosts, database access is controlled by each VOB's db_server process. You can configure one set of options for all VOBs on the host, or configure options that affect only specific VOBs.

The default database locking parameters are intended to deliver good performance under a wide range of loads. However, you might want to experiment with changing some of them, especially for individual VOBs that have many users.

To change database locking parameters that apply to all VOBs on a host that do not have their own locking parameters (see Step 2), modify the file /opt/rational/clearcase/config/vob/db/vob_almd_params, which contains a single line with the following format
```
 –u num –q num
```
The values of num for –u and – modify locking behavior as described here:
–u num

Specifies the maximum number of concurrent connections allowed to any VOB on the host or, if applied to an individual VOB (see Step 2), the maximum number of concurrent connections allowed to that VOB.

–q num

Specifies the number of lock requests that can be queued. When there are more than num lock requests outstanding, additional requests will be dropped. Poor user response time and messages of the form
db_VISTA database -922: lockmgr is busy

in the db_server_log or vobrpc_server_log files (and, often, concurrent timeout errors in a view_log file) may indicate that the value of the –q option should be raised. As a rule, this value should be no greater that five times the value of the –u option.

This file must owned by root and have read-only access.
Optional: To change database locking parameters that apply to an individual VOB, create a file named vob_almd_params in vob-storage-dir/db. File format and values are specified in Step 1.