ramdisk - RAM disk device driver
driver supports numerous ramdisk devices that are created by
the system during the boot process (see boot(8)
) or during normal system
operation (see ramdiskadm(8)
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
There are no alignment or length restrictions on I/O requests to either
block or character devices.
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
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.
Block device for ramdisk named 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
for descriptions of the following attribute:
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
|Interface Stability | Evolving |
SEE ALSO dkio(4I)
The percentage of available physical memory that can be allocated to
ramdisks is constrained by the variable rd_percent_physmem
. You can tune
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.
March 4, 2003 RAMDISK(4D)