Red Hat LINUX 7.2 Reference Manual page 90

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Can write CD-R:
Can write CD-RW: 0
Can read DVD:
Can write DVD-R: 0
Can write DVD-RAM: 0
This file can be quickly scanned to discover the qualities of an unknown CD-ROM, at least in the eyes
of the kernel. If multiple CD-ROMs are available on a system, each device is given its own column of
information.
Various files in /proc/sys/dev/cdrom, such as autoclose and checkmedia, can be used
to control the system's CD-ROM. Simply echo a 1 to the correct file to turn on the feature or a 0 to
disable a feature.
If RAID support is compiled into the kernel, a /proc/sys/dev/raid directory will be available
with at least two files in it: speed_limit_min and speed_limit_max. These settings come
into play in order to throttle or accelerate the speed the RAID device is utilized for particularly I/O
intensive tasks, such as resyncing the disks.
/proc/sys/fs
This directory contains an array of options and information concerning various aspects of the filesys-
tem, including quota, file handle, inode, and dentry information.
The binfmt_misc directory is used to provide kernel support for miscellaneous binary formats.
The important files in /proc/sys/fs include:
• dentry-state — Provides the status of the directory cache. The file looks similar to this:
57411 52939 45 0 0 0
The first number reveals the total number of directory cache entries, while the second number
displays the number of unused entries. The third number tells the number of seconds between
when a directory has been freed and when it can be reclaimed, and the fourth measures the pages
currently requested by the system. The last two numbers are not used and currently display only
zeros.
• dquot-nr — Shows the maximum number of cached disk quota entries.
• file-max — Allows you to change the maximum number of file handles that the kernel will
allocate. Raising the value in this file can resolve errors caused by a lack of available file handles.
• file-nr — Displays the number of allocated file handles, used file handles, and the maximum
number of file handles, in that order.
• overflowgid and overflowuid — Defines the fixed group ID and user ID, respectively,
for use with filesystems that only support 16-bit group and user IDs.
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Chapter 4:The /proc Filesystem