Return to ram CVS log

Up to [MW Coherent from dump] / coherent / a / usr / man / COHERENT

Annotation of coherent/a/usr/man/COHERENT/ram, revision 1.1

1.1     ! root        1: 
        !             2: 
        !             3: ram                       Device Driver                       ram
        !             4: 
        !             5: 
        !             6: 
        !             7: 
        !             8: RAM device driver
        !             9: 
        !            10: 
        !            11: The COHERENT  ram devices allow the user to  allocate and use the
        !            12: random access  memory (RAM) of  the computer system  directly.  A
        !            13: typical use  is for a RAM  disk, which is a  COHERENT file system
        !            14: kept in memory rather than on a diskette or hard disk.
        !            15: 
        !            16: The COHERENT RAM device driver has major number 8.  It can be ac-
        !            17: cessed either as a block-special device or as a character-special
        !            18: device.   The high-order  bit  of the  minor number  gives a  RAM
        !            19: device number (0 or 1), allowing the use of up to two RAM devices
        !            20: simultaneously.  The low-order seven bits specify the device size
        !            21: in 64  KB (128 block) increments.   The first open call  on a RAM
        !            22: device  with nonzero  size (1  to 127)  allocates memory  for the
        !            23: device; the  open call fails  if sufficient memory  is not avail-
        !            24: able.  Accessing a RAM device with a minor number specifying size
        !            25: 0  frees the  allocated memory, provided  all earlier  open calls
        !            26: have been closed.
        !            27: 
        !            28: Initially, COHERENT includes  two RAM block devices, 512KB device
        !            29: /dev/ram0 (8,  8) and 192KB  device /dev/ram1 (8,  131).  It also
        !            30: includes /dev/ram0close (8,  0) and /dev/ram1close (8, 128).  The
        !            31: system administrator  should change the RAM  devices to sizes ap-
        !            32: propriate for available system memory.
        !            33: 
        !            34: ***** Note *****
        !            35: 
        !            36: The  COHERENT  installation program  /etc/build  uses RAM  device
        !            37: /dev/ram1 as a  RAM disk during installation.  Programs compress,
        !            38: uncompress, zcat and  fsck sometimes use /dev/ram1 as a temporary
        !            39: storage device.  Users should avoid using /dev/ram1 as a RAM disk
        !            40: because of these programs.
        !            41: 
        !            42: ***** Examples *****
        !            43: 
        !            44: The following example  formats and mounts a 512-kilobyte RAM disk
        !            45: on directory /fast.
        !            46: 
        !            47: 
        !            48:         mkdir /fast
        !            49:         /etc/mkfs /dev/ram0 1024
        !            50:         /etc/mount /dev/ram0 /fast
        !            51: 
        !            52: 
        !            53: When the  RAM disk is no longer needed,  its allocated memory can
        !            54: be freed as follows:
        !            55: 
        !            56: 
        !            57:         /etc/umount /dev/ram0
        !            58:         cat /dev/null >/dev/ram0close
        !            59: 
        !            60: 
        !            61: 
        !            62: 
        !            63: 
        !            64: COHERENT Lexicon                                           Page 1
        !            65: 
        !            66: 
        !            67: 
        !            68: 
        !            69: ram                       Device Driver                       ram
        !            70: 
        !            71: 
        !            72: 
        !            73: The  next example  replaces  the default  /dev/ram0  with a  one-
        !            74: megabyte device containing a COHERENT file system.  The new minor
        !            75: number 16  specifies RAM device 0 and size  16 times 64 kilobytes
        !            76: (i.e., one  megabyte).  The new RAM  device contains 2,048 blocks
        !            77: of 512 bytes each.
        !            78: 
        !            79: 
        !            80:         rm /dev/ram0
        !            81:         /etc/mknod /dev/ram0 b 8 16
        !            82:         /etc/mkfs /dev/ram0 2048
        !            83: 
        !            84: 
        !            85: ***** Files *****
        !            86: 
        !            87: /dev/ram*
        !            88: 
        !            89: ***** See Also *****
        !            90: 
        !            91: compress, device drivers,  fsck, mkfs, mount, umount, uncompress,
        !            92: zcat
        !            93: 
        !            94: ***** Notes *****
        !            95: 
        !            96: Moving frequently  used commands or  files to a RAM  disk can im-
        !            97: prove system performance substantially.  However, the contents of
        !            98: a  RAM device  are lost  if the system  loses power,  reboots, or
        !            99: crashes, so changes to files kept  on a RAM disk should be stored
        !           100: frequently to the hard disk or to diskette.
        !           101: 
        !           102: If a RAM device uses most but not all of available system memory,
        !           103: its open  call will succeed but subsequent  commands may fail be-
        !           104: cause insufficient memory remains for the system.
        !           105: 
        !           106: 
        !           107: 
        !           108: 
        !           109: 
        !           110: 
        !           111: 
        !           112: 
        !           113: 
        !           114: 
        !           115: 
        !           116: 
        !           117: 
        !           118: 
        !           119: 
        !           120: 
        !           121: 
        !           122: 
        !           123: 
        !           124: 
        !           125: 
        !           126: 
        !           127: 
        !           128: 
        !           129: 
        !           130: COHERENT Lexicon                                           Page 2
        !           131: 
        !           132: 

This archive runs on limited infrastructure. Preserving old code on modern bandwidth. Automated agents are requested to crawl responsibly.