AIX Study--User access system resource restriction configuration

AIX Study--User access system resource restriction configuration

The system resource limits used by Aix users include two concepts---hard limits and soft limits (soft limits). Hard limits has been introduced since the AIX 4.1 release. Hard limits should be set by the AIX system administrator, and only members of the security group can increase this value, and the user itself can reduce this limit, but its changes will expire as the user exits from the system.

Use the following command to view the limit values for hard limits: Ulimit-hasoft limits is the upper limit used by the AIX core to restrict the use of processes to system resources. This value can be changed by anyone, but cannot exceed the hard limits value. It is important to note that only members of the security group can make changes permanent, and changes to ordinary AIX users will expire after they exit the system.

Use the following command to view the settings for the soft limits: ulimit-a
The following is the default value for the system's soft limits:

3.2 4.1-4.3 =============== ================= fsize = 2097151 fsize = 2097151 Core = 2048 Core = 2048 CPU = 3600 CPU = -1 data = 131072 data = 262144 RSS = 65536 RSS = 65536 stack = 8192 stack = 65536 nofiles = 2000* nofiles=2000 *

* This value (nofiles) can only be changed in Aix 4.3.1 or later versions.

fsize user-created file size limits. This definition value (512 bytes) is the size of the maximum file that the user can generate.
core (512 bytes).
CPU user process. A normal user can only reduce this value, and root can increase this value. It is important to note that the time the process uses the CPU depends on the AIX Kernel (core program) process scheduling algorithm, which is only referenced here.
data process data segment size.
stack process stack segment size.
rss process resident memory segment. The Aix core does not refer to this qualification.
nofiles process. This limit is fixed to 2000 in versions prior to Aix 4.3.1. This value can be increased to 32767 in the Aix 4.3.1 and later versions.

Among Aix users, here are three ways to modify these limits:
1. Edit the file/etc/security/limits and modify each defined value directly. This change takes effect after the system restarts.

2. Use the command Ulimit to modify the default values. For example:

Ulimit-f value ulimit-c <value> ulimit-t <value> ulimit-d <value> ulimit-s <value> ulimit-m <value> Ulimit-n <value>

The soft limit values for fsize, Core, Cpu,data, Stack, RSS, and Nofiles will be modified.

3. Use the command Chuser to modify a user's qualified value. For example:

Chuser fsize=<value> <username> chuser core=<value> <username chuser cpu=<value> < username> chuser data=<value> <username> chuser limit=<value> <username> chuser rss=< value> <username> chuser nofiles=<value> <username>

Change the soft limits of the user "username" to the value "value".

Chuser hard_fsize=<value> <username> chuser hard_core=<value> <username> chuser hard_cpu=< value> <username> chuser hard_data=<value> <username> chuser hard_limit=<value> < username> chuser hard_rss=<value> <username> chuser hard_nofiles=<value> <username>

Change the hard limits of the user "username" to the value "value".

Can be modified through the Smit tool:

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After modification, the configuration information is written to the/etc/security/limits

[[email protected]/] #cat/etc/security/limits

Oracle:fsize =-1 data =-1 stack =-1 core = 1

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AIX Study--User access system resource restriction configuration