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63 lines
1.5 KiB
63 lines
1.5 KiB
========= |
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dm-linear |
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========= |
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Device-Mapper's "linear" target maps a linear range of the Device-Mapper |
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device onto a linear range of another device. This is the basic building |
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block of logical volume managers. |
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Parameters: <dev path> <offset> |
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<dev path>: |
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Full pathname to the underlying block-device, or a |
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"major:minor" device-number. |
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<offset>: |
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Starting sector within the device. |
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Example scripts |
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=============== |
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:: |
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#!/bin/sh |
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# Create an identity mapping for a device |
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echo "0 `blockdev --getsz $1` linear $1 0" | dmsetup create identity |
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:: |
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#!/bin/sh |
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# Join 2 devices together |
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size1=`blockdev --getsz $1` |
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size2=`blockdev --getsz $2` |
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echo "0 $size1 linear $1 0 |
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$size1 $size2 linear $2 0" | dmsetup create joined |
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:: |
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#!/usr/bin/perl -w |
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# Split a device into 4M chunks and then join them together in reverse order. |
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my $name = "reverse"; |
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my $extent_size = 4 * 1024 * 2; |
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my $dev = $ARGV[0]; |
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my $table = ""; |
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my $count = 0; |
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if (!defined($dev)) { |
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die("Please specify a device.\n"); |
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} |
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my $dev_size = `blockdev --getsz $dev`; |
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my $extents = int($dev_size / $extent_size) - |
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(($dev_size % $extent_size) ? 1 : 0); |
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while ($extents > 0) { |
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my $this_start = $count * $extent_size; |
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$extents--; |
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$count++; |
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my $this_offset = $extents * $extent_size; |
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$table .= "$this_start $extent_size linear $dev $this_offset\n"; |
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} |
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`echo \"$table\" | dmsetup create $name`;
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