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| -rw-r--r-- | Documentation/device-mapper/switch.rst (renamed from Documentation/device-mapper/switch.txt) | 47 |
1 files changed, 25 insertions, 22 deletions
diff --git a/Documentation/device-mapper/switch.txt b/Documentation/device-mapper/switch.rst index 5bd4831db4a8..7dde06be1a4f 100644 --- a/Documentation/device-mapper/switch.txt +++ b/Documentation/device-mapper/switch.rst @@ -1,3 +1,4 @@ +========= dm-switch ========= @@ -67,27 +68,25 @@ b-tree can achieve. Construction Parameters ======================= - <num_paths> <region_size> <num_optional_args> [<optional_args>...] - [<dev_path> <offset>]+ - -<num_paths> - The number of paths across which to distribute the I/O. + <num_paths> <region_size> <num_optional_args> [<optional_args>...] [<dev_path> <offset>]+ + <num_paths> + The number of paths across which to distribute the I/O. -<region_size> - The number of 512-byte sectors in a region. Each region can be redirected - to any of the available paths. + <region_size> + The number of 512-byte sectors in a region. Each region can be redirected + to any of the available paths. -<num_optional_args> - The number of optional arguments. Currently, no optional arguments - are supported and so this must be zero. + <num_optional_args> + The number of optional arguments. Currently, no optional arguments + are supported and so this must be zero. -<dev_path> - The block device that represents a specific path to the device. + <dev_path> + The block device that represents a specific path to the device. -<offset> - The offset of the start of data on the specific <dev_path> (in units - of 512-byte sectors). This number is added to the sector number when - forwarding the request to the specific path. Typically it is zero. + <offset> + The offset of the start of data on the specific <dev_path> (in units + of 512-byte sectors). This number is added to the sector number when + forwarding the request to the specific path. Typically it is zero. Messages ======== @@ -122,17 +121,21 @@ Example Assume that you have volumes vg1/switch0 vg1/switch1 vg1/switch2 with the same size. -Create a switch device with 64kB region size: +Create a switch device with 64kB region size:: + dmsetup create switch --table "0 `blockdev --getsz /dev/vg1/switch0` switch 3 128 0 /dev/vg1/switch0 0 /dev/vg1/switch1 0 /dev/vg1/switch2 0" Set mappings for the first 7 entries to point to devices switch0, switch1, -switch2, switch0, switch1, switch2, switch1: +switch2, switch0, switch1, switch2, switch1:: + dmsetup message switch 0 set_region_mappings 0:0 :1 :2 :0 :1 :2 :1 -Set repetitive mapping. This command: +Set repetitive mapping. This command:: + dmsetup message switch 0 set_region_mappings 1000:1 :2 R2,10 -is equivalent to: + +is equivalent to:: + dmsetup message switch 0 set_region_mappings 1000:1 :2 :1 :2 :1 :2 :1 :2 \ :1 :2 :1 :2 :1 :2 :1 :2 :1 :2 - |