diff options
Diffstat (limited to 'Documentation/admin-guide/device-mapper')
| -rw-r--r-- | Documentation/admin-guide/device-mapper/dm-dust.rst (renamed from Documentation/admin-guide/device-mapper/dm-dust.txt) | 243 | ||||
| -rw-r--r-- | Documentation/admin-guide/device-mapper/index.rst | 1 |
2 files changed, 130 insertions, 114 deletions
diff --git a/Documentation/admin-guide/device-mapper/dm-dust.txt b/Documentation/admin-guide/device-mapper/dm-dust.rst index 954d402a1f6a..b6e7e7ead831 100644 --- a/Documentation/admin-guide/device-mapper/dm-dust.txt +++ b/Documentation/admin-guide/device-mapper/dm-dust.rst @@ -31,218 +31,233 @@ configured "bad blocks" will be treated as bad, or bypassed. This allows the pre-writing of test data and metadata prior to simulating a "failure" event where bad sectors start to appear. -Table parameters: ------------------ +Table parameters +---------------- <device_path> <offset> <blksz> Mandatory parameters: - <device_path>: path to the block device. - <offset>: offset to data area from start of device_path - <blksz>: block size in bytes + <device_path>: + Path to the block device. + + <offset>: + Offset to data area from start of device_path + + <blksz>: + Block size in bytes + (minimum 512, maximum 1073741824, must be a power of 2) -Usage instructions: -------------------- +Usage instructions +------------------ -First, find the size (in 512-byte sectors) of the device to be used: +First, find the size (in 512-byte sectors) of the device to be used:: -$ sudo blockdev --getsz /dev/vdb1 -33552384 + $ sudo blockdev --getsz /dev/vdb1 + 33552384 Create the dm-dust device: (For a device with a block size of 512 bytes) -$ sudo dmsetup create dust1 --table '0 33552384 dust /dev/vdb1 0 512' + +:: + + $ sudo dmsetup create dust1 --table '0 33552384 dust /dev/vdb1 0 512' (For a device with a block size of 4096 bytes) -$ sudo dmsetup create dust1 --table '0 33552384 dust /dev/vdb1 0 4096' + +:: + + $ sudo dmsetup create dust1 --table '0 33552384 dust /dev/vdb1 0 4096' Check the status of the read behavior ("bypass" indicates that all I/O -will be passed through to the underlying device): -$ sudo dmsetup status dust1 -0 33552384 dust 252:17 bypass +will be passed through to the underlying device):: + + $ sudo dmsetup status dust1 + 0 33552384 dust 252:17 bypass -$ sudo dd if=/dev/mapper/dust1 of=/dev/null bs=512 count=128 iflag=direct -128+0 records in -128+0 records out + $ sudo dd if=/dev/mapper/dust1 of=/dev/null bs=512 count=128 iflag=direct + 128+0 records in + 128+0 records out -$ sudo dd if=/dev/zero of=/dev/mapper/dust1 bs=512 count=128 oflag=direct -128+0 records in -128+0 records out + $ sudo dd if=/dev/zero of=/dev/mapper/dust1 bs=512 count=128 oflag=direct + 128+0 records in + 128+0 records out -Adding and removing bad blocks: -------------------------------- +Adding and removing bad blocks +------------------------------ At any time (i.e.: whether the device has the "bad block" emulation enabled or disabled), bad blocks may be added or removed from the -device via the "addbadblock" and "removebadblock" messages: +device via the "addbadblock" and "removebadblock" messages:: -$ sudo dmsetup message dust1 0 addbadblock 60 -kernel: device-mapper: dust: badblock added at block 60 + $ sudo dmsetup message dust1 0 addbadblock 60 + kernel: device-mapper: dust: badblock added at block 60 -$ sudo dmsetup message dust1 0 addbadblock 67 -kernel: device-mapper: dust: badblock added at block 67 + $ sudo dmsetup message dust1 0 addbadblock 67 + kernel: device-mapper: dust: badblock added at block 67 -$ sudo dmsetup message dust1 0 addbadblock 72 -kernel: device-mapper: dust: badblock added at block 72 + $ sudo dmsetup message dust1 0 addbadblock 72 + kernel: device-mapper: dust: badblock added at block 72 These bad blocks will be stored in the "bad block list". -While the device is in "bypass" mode, reads and writes will succeed: +While the device is in "bypass" mode, reads and writes will succeed:: -$ sudo dmsetup status dust1 -0 33552384 dust 252:17 bypass + $ sudo dmsetup status dust1 + 0 33552384 dust 252:17 bypass -Enabling block read failures: ------------------------------ +Enabling block read failures +---------------------------- -To enable the "fail read on bad block" behavior, send the "enable" message: +To enable the "fail read on bad block" behavior, send the "enable" message:: -$ sudo dmsetup message dust1 0 enable -kernel: device-mapper: dust: enabling read failures on bad sectors + $ sudo dmsetup message dust1 0 enable + kernel: device-mapper: dust: enabling read failures on bad sectors -$ sudo dmsetup status dust1 -0 33552384 dust 252:17 fail_read_on_bad_block + $ sudo dmsetup status dust1 + 0 33552384 dust 252:17 fail_read_on_bad_block With the device in "fail read on bad block" mode, attempting to read a -block will encounter an "Input/output error": +block will encounter an "Input/output error":: -$ sudo dd if=/dev/mapper/dust1 of=/dev/null bs=512 count=1 skip=67 iflag=direct -dd: error reading '/dev/mapper/dust1': Input/output error -0+0 records in -0+0 records out -0 bytes copied, 0.00040651 s, 0.0 kB/s + $ sudo dd if=/dev/mapper/dust1 of=/dev/null bs=512 count=1 skip=67 iflag=direct + dd: error reading '/dev/mapper/dust1': Input/output error + 0+0 records in + 0+0 records out + 0 bytes copied, 0.00040651 s, 0.0 kB/s ...and writing to the bad blocks will remove the blocks from the list, -therefore emulating the "remap" behavior of hard disk drives: +therefore emulating the "remap" behavior of hard disk drives:: -$ sudo dd if=/dev/zero of=/dev/mapper/dust1 bs=512 count=128 oflag=direct -128+0 records in -128+0 records out + $ sudo dd if=/dev/zero of=/dev/mapper/dust1 bs=512 count=128 oflag=direct + 128+0 records in + 128+0 records out -kernel: device-mapper: dust: block 60 removed from badblocklist by write -kernel: device-mapper: dust: block 67 removed from badblocklist by write -kernel: device-mapper: dust: block 72 removed from badblocklist by write -kernel: device-mapper: dust: block 87 removed from badblocklist by write + kernel: device-mapper: dust: block 60 removed from badblocklist by write + kernel: device-mapper: dust: block 67 removed from badblocklist by write + kernel: device-mapper: dust: block 72 removed from badblocklist by write + kernel: device-mapper: dust: block 87 removed from badblocklist by write -Bad block add/remove error handling: ------------------------------------- +Bad block add/remove error handling +----------------------------------- Attempting to add a bad block that already exists in the list will -result in an "Invalid argument" error, as well as a helpful message: +result in an "Invalid argument" error, as well as a helpful message:: -$ sudo dmsetup message dust1 0 addbadblock 88 -device-mapper: message ioctl on dust1 failed: Invalid argument -kernel: device-mapper: dust: block 88 already in badblocklist + $ sudo dmsetup message dust1 0 addbadblock 88 + device-mapper: message ioctl on dust1 failed: Invalid argument + kernel: device-mapper: dust: block 88 already in badblocklist Attempting to remove a bad block that doesn't exist in the list will -result in an "Invalid argument" error, as well as a helpful message: +result in an "Invalid argument" error, as well as a helpful message:: -$ sudo dmsetup message dust1 0 removebadblock 87 -device-mapper: message ioctl on dust1 failed: Invalid argument -kernel: device-mapper: dust: block 87 not found in badblocklist + $ sudo dmsetup message dust1 0 removebadblock 87 + device-mapper: message ioctl on dust1 failed: Invalid argument + kernel: device-mapper: dust: block 87 not found in badblocklist -Counting the number of bad blocks in the bad block list: --------------------------------------------------------- +Counting the number of bad blocks in the bad block list +------------------------------------------------------- To count the number of bad blocks configured in the device, run the -following message command: +following message command:: -$ sudo dmsetup message dust1 0 countbadblocks + $ sudo dmsetup message dust1 0 countbadblocks A message will print with the number of bad blocks currently -configured on the device: +configured on the device:: -kernel: device-mapper: dust: countbadblocks: 895 badblock(s) found + kernel: device-mapper: dust: countbadblocks: 895 badblock(s) found -Querying for specific bad blocks: ---------------------------------- +Querying for specific bad blocks +-------------------------------- To find out if a specific block is in the bad block list, run the -following message command: +following message command:: -$ sudo dmsetup message dust1 0 queryblock 72 + $ sudo dmsetup message dust1 0 queryblock 72 -The following message will print if the block is in the list: -device-mapper: dust: queryblock: block 72 found in badblocklist +The following message will print if the block is in the list:: -The following message will print if the block is in the list: -device-mapper: dust: queryblock: block 72 not found in badblocklist + device-mapper: dust: queryblock: block 72 found in badblocklist + +The following message will print if the block is not in the list:: + + device-mapper: dust: queryblock: block 72 not found in badblocklist The "queryblock" message command will work in both the "enabled" and "disabled" modes, allowing the verification of whether a block will be treated as "bad" without having to issue I/O to the device, or having to "enable" the bad block emulation. -Clearing the bad block list: ----------------------------- +Clearing the bad block list +--------------------------- To clear the bad block list (without needing to individually run a "removebadblock" message command for every block), run the -following message command: +following message command:: -$ sudo dmsetup message dust1 0 clearbadblocks + $ sudo dmsetup message dust1 0 clearbadblocks -After clearing the bad block list, the following message will appear: +After clearing the bad block list, the following message will appear:: -kernel: device-mapper: dust: clearbadblocks: badblocks cleared + kernel: device-mapper: dust: clearbadblocks: badblocks cleared If there were no bad blocks to clear, the following message will -appear: +appear:: -kernel: device-mapper: dust: clearbadblocks: no badblocks found + kernel: device-mapper: dust: clearbadblocks: no badblocks found -Message commands list: ----------------------- +Message commands list +--------------------- Below is a list of the messages that can be sent to a dust device: -Operations on blocks (requires a <blknum> argument): +Operations on blocks (requires a <blknum> argument):: -addbadblock <blknum> -queryblock <blknum> -removebadblock <blknum> + addbadblock <blknum> + queryblock <blknum> + removebadblock <blknum> ...where <blknum> is a block number within range of the device - (corresponding to the block size of the device.) +(corresponding to the block size of the device.) -Single argument message commands: +Single argument message commands:: -countbadblocks -clearbadblocks -disable -enable -quiet + countbadblocks + clearbadblocks + disable + enable + quiet -Device removal: ---------------- +Device removal +-------------- -When finished, remove the device via the "dmsetup remove" command: +When finished, remove the device via the "dmsetup remove" command:: -$ sudo dmsetup remove dust1 + $ sudo dmsetup remove dust1 -Quiet mode: ------------ +Quiet mode +---------- On test runs with many bad blocks, it may be desirable to avoid excessive logging (from bad blocks added, removed, or "remapped"). -This can be done by enabling "quiet mode" via the following message: +This can be done by enabling "quiet mode" via the following message:: -$ sudo dmsetup message dust1 0 quiet + $ sudo dmsetup message dust1 0 quiet This will suppress log messages from add / remove / removed by write operations. Log messages from "countbadblocks" or "queryblock" message commands will still print in quiet mode. -The status of quiet mode can be seen by running "dmsetup status": +The status of quiet mode can be seen by running "dmsetup status":: -$ sudo dmsetup status dust1 -0 33552384 dust 252:17 fail_read_on_bad_block quiet + $ sudo dmsetup status dust1 + 0 33552384 dust 252:17 fail_read_on_bad_block quiet -To disable quiet mode, send the "quiet" message again: +To disable quiet mode, send the "quiet" message again:: -$ sudo dmsetup message dust1 0 quiet + $ sudo dmsetup message dust1 0 quiet -$ sudo dmsetup status dust1 -0 33552384 dust 252:17 fail_read_on_bad_block verbose + $ sudo dmsetup status dust1 + 0 33552384 dust 252:17 fail_read_on_bad_block verbose (The presence of "verbose" indicates normal logging.) diff --git a/Documentation/admin-guide/device-mapper/index.rst b/Documentation/admin-guide/device-mapper/index.rst index c77c58b8f67b..4872fb6d2952 100644 --- a/Documentation/admin-guide/device-mapper/index.rst +++ b/Documentation/admin-guide/device-mapper/index.rst @@ -9,6 +9,7 @@ Device Mapper cache delay dm-crypt + dm-dust dm-flakey dm-init dm-integrity |