Chapter 3 General System Administration

This chapter describes how to use these new system administration features.

• "DNLC Improvements"

• "Extended Accounting Features"

For the most up-to-date man pages, use the man command. The Solaris 8 6/00 man pages include new feature information not found in the Solaris 8 Reference Manual Collection.

DNLC Improvements

This functionality is updated in the Solaris 8 6/00 software release.

The Enhanced Directory Name Look-up Cache (DNLC) is enhanced in the Solaris 8 6/00 software release to provide improved performance when accessing files in large directories with 1,000 or more files. The information here adds to information on managing system performance found in "System Performance (Overview)" in System Administration Guide, Volume 2.

The DNLC is a general file system service that caches the most recently referenced directory names and their associated vnodes. UFS directory entries are stored linearly on disk. This means locating an entry requires searching each entry for the name. Adding a new entry requires searching the entire directory to ensure the name does not exist. To solve this performance problem, entire directories are cached in memory by the DNLC.

Another feature in this release is DNLC caching of file objects that have been looked up, but do not exist. This is known as negative caching, and is useful because some applications repeatedly test to see if a file exists or not.

The section that follows describes the new DNLC tunable parameters. These parameters are set optimally and should not be changed casually.

MAXUINT is the maximum value of an unsigned integer.

dnlc_dir_enable

Description

Enables large directory caching

Data Type

Unsigned integer

Default Value

1 (enabled)

Range

0 (disabled), 1 (enabled)

When to Change

Directory caching has no known problems, but if problems occur, then set dnlc_dir_enable to 0 to disable caching.

dnlc_dir_min_size

Description

Minimum number of entries cached for one directory

Data Type

Unsigned integer

Default Value

40

Range

0 to MAXUINT (no maximum)

When to Change

If performance problems occur with caching small directories, then increase dnlc_dir_min_size. Note that individual file systems might have their own range limits for caching directories. For instance, UFS limits directories to a minimum of ufs_min_dir_cache bytes (approximately 1024 entries), assuming 16 bytes per entry.

dnlc_dir_max_size

Description

Maximum number of directory entries before caching

Data Type

Unsigned integer

Default Value

MAXUINT (no maximum)

Range

0 to MAXUINT

When to Change

If performance problems occur with large directories, then decrease dnlc_dir_max_size.

Extended Accounting Features

This functionality is updated in the Solaris 8 6/00 software release.

The Solaris accounting software has been updated in the Solaris 8 6/00 release. This information supplements information on using system accounting for managing resources found in "Managing System Accounting (Tasks)" in System Administration Guide, Volume 2.

Extended accounting introduces a new, variable length general-purpose accounting file format that represents general groups of accounting data, as well as the ability to configure resource utilization recorded by the kernel in the various accounting files. Extended accounting features include:

• Tasks -- New process collectives for tracking resource usage

• Projects-- New administrative databases for charging resource usage. Resource usage by a task can be charged to a project.

• acctadm-- Anew tool for configuring various attributes of the extended accounting facility. For example, the resources tracked by the accounting system can be configured on a system-wide basis.

The new default accounting configuration requires no administration and causes no complications. If you do use the extended accounting features, however, do not remove the /etc/project file, which contains important information about the extended accounting configuration.