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61 lines
1.8 KiB
61 lines
1.8 KiB
========= |
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dm-stripe |
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========= |
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Device-Mapper's "striped" target is used to create a striped (i.e. RAID-0) |
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device across one or more underlying devices. Data is written in "chunks", |
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with consecutive chunks rotating among the underlying devices. This can |
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potentially provide improved I/O throughput by utilizing several physical |
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devices in parallel. |
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Parameters: <num devs> <chunk size> [<dev path> <offset>]+ |
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<num devs>: |
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Number of underlying devices. |
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<chunk size>: |
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Size of each chunk of data. Must be at least as |
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large as the system's PAGE_SIZE. |
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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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One or more underlying devices can be specified. The striped device size must |
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be a multiple of the chunk size multiplied by the number of underlying devices. |
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Example scripts |
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=============== |
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:: |
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#!/usr/bin/perl -w |
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# Create a striped device across any number of underlying devices. The device |
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# will be called "stripe_dev" and have a chunk-size of 128k. |
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my $chunk_size = 128 * 2; |
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my $dev_name = "stripe_dev"; |
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my $num_devs = @ARGV; |
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my @devs = @ARGV; |
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my ($min_dev_size, $stripe_dev_size, $i); |
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if (!$num_devs) { |
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die("Specify at least one device\n"); |
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} |
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$min_dev_size = `blockdev --getsz $devs[0]`; |
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for ($i = 1; $i < $num_devs; $i++) { |
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my $this_size = `blockdev --getsz $devs[$i]`; |
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$min_dev_size = ($min_dev_size < $this_size) ? |
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$min_dev_size : $this_size; |
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} |
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$stripe_dev_size = $min_dev_size * $num_devs; |
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$stripe_dev_size -= $stripe_dev_size % ($chunk_size * $num_devs); |
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$table = "0 $stripe_dev_size striped $num_devs $chunk_size"; |
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for ($i = 0; $i < $num_devs; $i++) { |
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$table .= " $devs[$i] 0"; |
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} |
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`echo $table | dmsetup create $dev_name`;
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