GNU/Linux man pages
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Expressions régulières,
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Unix |
Unix v6 |
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rk(4) |
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rk RK-11/RK03 (or RK05) disk refers to an entire RK03 disk as a single sequentially-addressed file. Its 256-word blocks are numbered 0 to 4871. Drive numbers (minor devices) of eight and larger are treated specially. Drive 8+x is the x+1 way interleaving of devices rk0 to rkx. Thus blocks on rk10 are distributed alternately among rk0, rk1, and rk2. The files discussed above access the disk via the system’s normal buffering mechanism and may be read and written without regard to physical disk records. There is also a ‘‘raw’’ interface which provides for direct transmission between the disk and the user’s read or write buffer. A single read or write call results in exactly one I/O operation and therefore raw I/O is considerably more efficient when many words are transmitted. The names of the raw RK files begin with and end with a number which selects the same disk as the corresponding file. In raw I/O the buffer must begin on a word boundary, and counts should be a multiple of 512 bytes (a disk block). Likewise calls should specify a multiple of 512 bytes. /dev/rk?, /dev/rrk? Care should be taken in using the interleaved files. First, the same drive should not be accessed simultaneously using the ordinary name and as part of an interleaved file, because the same physical blocks have in effect two different names; this fools the system’s buffering strategy. Second, the combined files cannot be used for swapping or raw I/O.
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rk(4) | |