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Tor-ramdisk 20080606 (Default branch)
06-11-2008
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ramdisk(7D) 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 nor- mal 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 TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Interface Stability |Evolving | +-----------------------------+-----------------------------+ 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. SunOS 5.10 04 Mar 2003 ramdisk(7D)