Performance Tuning for Linux Servers [Electronic resources]

Sandra K. Johnson

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File System

Sysctl Prefix: fs

/proc Prefix: /proc/sys/fs/

Parameter

Description

file-max

Maximum number of file descriptors

file-nr

Number of file handles

The system file_descriptor limit is set using file-max. The descriptor limit is the maximum number of file descriptors that any one process may open at once. The file-nr has three fields: the number of allocated file handles, the number of used file handles, and the maximum number of file handles.

Parameter

Description

inode-state

Inode status

inode-nr

Free and used inodes

The first field of inode-state, nr_inodes, denotes the number of inodes the system has allocated. The second field, nr_free_inodes, specifies the number of free inodes. The inode-nr parameter contains the first two fields of the inode-state parameter.

Parameter

Description

super-max

Maximum number of file systems

super-nr

Number of mounted file systems

The super-max parameter controls the maximum number of super blocks and thus determines the maximum number of mounted file systems the kernel can have. This value needs to be increased if there is a need to mount more file systems than the current value in super-max.

Parameter

Description

dentry-state

Status of directory cache

The directory entries are dynamically allocated and deleted. These parameter values show the current status. The first field, nr_dentry, specifies the number of directory entries. The second field, nr_unused, specifies the number of unused directory entries.

Parameter

Description

dquot-nr

Number of allocated and free disk quota entries

dquot-max

Maximum number of cached disk quota entries

Parameter

Description

dir-notify-enable

Enables dnotify

The dir-notify-enable field enables or disables the dnotify interface on a system-wide basis.

Parameter

Description

aio-max-nr

Maximum number of AIO requests

aio-nr

Number of AIO requests