Devices ramdisk(7D)
NAME
ramdisk - RAM disk device driver
SYNOPSIS
ramdisk@0: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 (seeramdiskadm(1M) for more information).
DEVICE SPECIAL FILESEach 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 diskrecords. 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 asingle I/O operation, meaning that raw I/O is more effi-
cient when many bytes are transmitted. You can find blockfiles 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.
SunOS 5.11 Last change: 04 Mar 2003 1
Devices ramdisk(7D)
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 attri-
bute:____________________________________________________________
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
|_____________________________|_____________________________|
| Interface Stability | Committed ||_____________________________|_____________________________|
SEE ALSO
ramdiskadm(1M), fsck(1M), fstyp(1M), mount(1M), newfs(1M),
driver.conf(4), filesystem(5), dkio(7I) NOTESSunOS 5.11 Last change: 04 Mar 2003 2
Devices ramdisk(7D)
The percentage of available physical memory that can beallocated 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 ofavailable 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.
SunOS 5.11 Last change: 04 Mar 2003 3