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1=========2dm-stripe3=========4 5Device-Mapper's "striped" target is used to create a striped (i.e. RAID-0)6device across one or more underlying devices. Data is written in "chunks",7with consecutive chunks rotating among the underlying devices. This can8potentially provide improved I/O throughput by utilizing several physical9devices in parallel.10 11Parameters: <num devs> <chunk size> [<dev path> <offset>]+12 <num devs>:13 Number of underlying devices.14 <chunk size>:15 Size of each chunk of data. Must be at least as16 large as the system's PAGE_SIZE.17 <dev path>:18 Full pathname to the underlying block-device, or a19 "major:minor" device-number.20 <offset>:21 Starting sector within the device.22 23One or more underlying devices can be specified. The striped device size must24be a multiple of the chunk size multiplied by the number of underlying devices.25 26 27Example scripts28===============29 30::31 32 #!/usr/bin/perl -w33 # Create a striped device across any number of underlying devices. The device34 # will be called "stripe_dev" and have a chunk-size of 128k.35 36 my $chunk_size = 128 * 2;37 my $dev_name = "stripe_dev";38 my $num_devs = @ARGV;39 my @devs = @ARGV;40 my ($min_dev_size, $stripe_dev_size, $i);41 42 if (!$num_devs) {43 die("Specify at least one device\n");44 }45 46 $min_dev_size = `blockdev --getsz $devs[0]`;47 for ($i = 1; $i < $num_devs; $i++) {48 my $this_size = `blockdev --getsz $devs[$i]`;49 $min_dev_size = ($min_dev_size < $this_size) ?50 $min_dev_size : $this_size;51 }52 53 $stripe_dev_size = $min_dev_size * $num_devs;54 $stripe_dev_size -= $stripe_dev_size % ($chunk_size * $num_devs);55 56 $table = "0 $stripe_dev_size striped $num_devs $chunk_size";57 for ($i = 0; $i < $num_devs; $i++) {58 $table .= " $devs[$i] 0";59 }60 61 `echo $table | dmsetup create $dev_name`;62