Based on kernel version 4.16.1. Page generated on 2018-04-09 11:52 EST.
1 dm-flakey 2 ========= 3 4 This target is the same as the linear target except that it exhibits 5 unreliable behaviour periodically. It's been found useful in simulating 6 failing devices for testing purposes. 7 8 Starting from the time the table is loaded, the device is available for 9 <up interval> seconds, then exhibits unreliable behaviour for <down 10 interval> seconds, and then this cycle repeats. 11 12 Also, consider using this in combination with the dm-delay target too, 13 which can delay reads and writes and/or send them to different 14 underlying devices. 15 16 Table parameters 17 ---------------- 18 <dev path> <offset> <up interval> <down interval> \ 19 [<num_features> [<feature arguments>]] 20 21 Mandatory parameters: 22 <dev path>: Full pathname to the underlying block-device, or a 23 "major:minor" device-number. 24 <offset>: Starting sector within the device. 25 <up interval>: Number of seconds device is available. 26 <down interval>: Number of seconds device returns errors. 27 28 Optional feature parameters: 29 If no feature parameters are present, during the periods of 30 unreliability, all I/O returns errors. 31 32 drop_writes: 33 All write I/O is silently ignored. 34 Read I/O is handled correctly. 35 36 corrupt_bio_byte <Nth_byte> <direction> <value> <flags>: 37 During <down interval>, replace <Nth_byte> of the data of 38 each matching bio with <value>. 39 40 <Nth_byte>: The offset of the byte to replace. 41 Counting starts at 1, to replace the first byte. 42 <direction>: Either 'r' to corrupt reads or 'w' to corrupt writes. 43 'w' is incompatible with drop_writes. 44 <value>: The value (from 0-255) to write. 45 <flags>: Perform the replacement only if bio->bi_opf has all the 46 selected flags set. 47 48 Examples: 49 corrupt_bio_byte 32 r 1 0 50 - replaces the 32nd byte of READ bios with the value 1 51 52 corrupt_bio_byte 224 w 0 32 53 - replaces the 224th byte of REQ_META (=32) bios with the value 0