ramdisk(7d) - osol9

1ramdisk(7D)                         Devices                        ramdisk(7D)
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NAME

6       ramdisk - RAM disk device driver
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SYNOPSIS

9       ramdisk@0:diskname
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DESCRIPTION

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

18       Each  ramdisk  can  be  accessed  either  as a block device or as a raw
19       device.  When  accessed  as  a  block  device,  the  normal   buffering
20       mechanism  is used when reading from and writing to the device, without
21       regard to physical disk records. Accessing the ramdisk as a raw  device
22       enables direct transmission between the disk and the read or write buf‐
23       fer. A single read or write call usually results in a single  I/O oper‐
24       ation,  meaning  that  raw  I/O  is  more efficient when many bytes are
25       transmitted. You can find block files names in /dev/ramdisk.  Raw  file
26       names are found in /dev/rramdisk.
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29       There are no alignment or length restrictions on I/O requests to either
30       block or character devices.
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ERRORS

33       EFAULT    The argument features a bad address.
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36       EINVAL    Invalid argument. EIO. An I/O error occurred.
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39       EPERM     Cannot create or delete a ramdisk without write permission on
40                 /dev/ramdiskctl.
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43       ENOTTY    The device does not support the requested ioctl function.
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46       ENXIO     The device did not exist during opening.
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49       EBUSY     Cannot exclusively open /dev/ramdiskctl. One or more ramdisks
50                 are still open.
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53       EEXIST    A ramdisk with the indicated name already exists.
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56       EAGAIN    Cannot allocate resource for ramdisk. Try again later.
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FILES

60       /dev/ramdisk/diskname
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62           Block device for ramdisk named diskname.
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65       /dev/rramdisk/diskname
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67           Raw device for ramdisk name diskname
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70       /kernel/drv/ramdisk
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72           32-bit driver
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75       /kernel/drv/ramdisk.conf
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77           Driver configuration file. (Do not alter).
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80       /kernel/drv/sparcv9/ramdisk
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82           64-bit driver
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ATTRIBUTES

86       See attributes(5) for descriptions of the following attribute:
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91       ┌─────────────────────────────┬─────────────────────────────┐
92       │      ATTRIBUTE TYPE         │      ATTRIBUTE VALUE        │
93       ├─────────────────────────────┼─────────────────────────────┤
94       │Interface Stability          │Evolving                     │
95       └─────────────────────────────┴─────────────────────────────┘
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NOTES

102       The  percentage  of  available physical memory that can be allocated to
103       ramdisks is constrained by the  variable  rd_percent_physmem.  You  can
104       tune  the  rd_percent_physmem  variable in /etc/system. By default, the
105       percentage of available  physical  memory  that  can  be  allocated  to
106       ramdisks is fixed at 25%.
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109       A  ramdisk  may  not be the best possible use of system memory. Accord‐
110       ingly, use ramdisks only when absolutely necessary.
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114SunOS 5.11                        04 Mar 2003                      ramdisk(7D)