A.1.2. The striped Mapping Target

A.1.2. The striped Mapping Target

The striped mapping target supports striping across physical devices. It takes as arguments the number of stripes and the striping chunk size followed by a list of pairs of device name and sector. The format of a striped target is as follows:

start length striped #stripes chunk_size device1 offset1 ... deviceN offsetN

There is one set of device and offset parameters for each stripe.

start

starting block in virtual device

length

length of this segment

#stripes

number of stripes for the virtual device

chunk_size

number of sectors written to each stripe before switching to the next; must be power of 2 at least as big as the kernel page size

device

block device, referenced by the device name in the filesystem or by the major and minor numbers in the format major:minor.

offset

starting offset of the mapping on the device

The following example shows a striped target with three stripes and a chunk size of 128:

0 73728 striped 3 128 8:9 384 8:8 384 8:7 9789824
0

starting block in virtual device

73728

length of this segment

striped 3 128

stripe across three devices with chunk size of 128 blocks

8:9

major:minor numbers of first device

384

starting offset of the mapping on the first device

8:8

major:minor numbers of second device

384

starting offset of the mapping on the second device

8:7

major:minor numbers of of third device

9789824

starting offset of the mapping on the third device

The following example shows a striped target for 2 stripes with 256 KiB chunks, with the device parameters specified by the device names in the file system rather than by the major and minor numbers.

0 65536 striped 2 512 /dev/hda 0 /dev/hdb 0

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