Content-type: text/html Man page of ramdisk

ramdisk

Section: Devices (7D)
Updated: 04 Mar 2003
Index Return to Main Contents
 

NAME

ramdisk - RAM disk device driver  

SYNOPSIS

[email protected]:diskname
 

DESCRIPTION

The ramdisk driver supports numerous ramdisk devices that are created by the system during the boot process (see boot(1M)) or during normal system operation (see ramdiskadm(1M) for more information).  

DEVICE SPECIAL FILES

Each ramdisk can be accessed either as a block device or as a raw device. When accessed as a block device, the normal buffering mechanism is used when reading from and writing to the device, without regard to physical disk records. Accessing the ramdisk as a raw device enables direct transmission between the disk and the read or write buffer. A single read or write call usually results in a single I/O operation, meaning that raw I/O is more efficient when many bytes are transmitted. You can find block files names in /dev/ramdisk. Raw file names are found in /dev/rramdisk.

There are no alignment or length restrictions on I/O requests to either block or character devices.  

ERRORS

EFAULT The argument features a bad address.

EINVAL Invalid argument. EIO. An I/O error occurred.

EPERM Cannot create or delete a ramdisk without write permission on /dev/ramdiskctl.

ENOTTY The device does not support the requested ioctl function.

ENXIO The device did not exist during opening.

EBUSY Cannot exclusively open /dev/ramdiskctl. One or more ramdisks are still open.

EEXIST A ramdisk with the indicated name already exists.

EAGAIN Cannot allocate resource for ramdisk. Try again later.

 

FILES

/dev/ramdisk/diskname

Block device for ramdisk named diskname.

/dev/rramdisk/diskname

Raw device for ramdisk name diskname

/kernel/drv/ramdisk

32-bit driver

/kernel/drv/ramdisk.conf

Driver configuration file. (Do not alter).

/kernel/drv/sparcv9/ramdisk

64-bit driver

 

ATTRIBUTES

See attributes(5) for descriptions of the following attribute:

ATTRIBUTE TYPEATTRIBUTE VALUE
Interface StabilityEvolving

 

SEE ALSO

ramdiskadm(1M), fsck(1M), fstyp(1M), mount(1M), newfs(1M), driver.conf(4), filesystem(5), dkio(7I)  

NOTES

The percentage of available physical memory that can be allocated to ramdisks is constrained by the variable rd_percent_physmem. You can tune the rd_percent_physmem variable in /etc/system. By default, the percentage of available physical memory that can be allocated to ramdisks is fixed at 25%.

A ramdisk may not be the best possible use of system memory. Accordingly, use ramdisks only when absolutely necessary.


 

Index

NAME
SYNOPSIS
DESCRIPTION
DEVICE SPECIAL FILES
ERRORS
FILES
ATTRIBUTES
SEE ALSO
NOTES

This document was created by man2html, using the manual pages.
Time: 02:39:59 GMT, October 02, 2010