admin-guide/device-mapper/dm-integrity.rst

12 To guarantee write atomicity, the dm-integrity target uses journal, it
13 writes sector data and integrity tags into a journal, commits the journal
29 instead of a journal. If a bit in the bitmap is 1, the corresponding
32 is faster than the journal mode, because we don't have to write the data
75 	D - direct writes (without journal)
82 		journal and atomicity is guaranteed. In case of crash,
90 	R - recovery mode - in this mode, journal is not replayed,
101 	The size of journal, this argument is used only if formatting the
119 	The journal watermark in percents. When the size of the journal
120 	exceeds this watermark, the thread that flushes the journal will
124 	Commit time in milliseconds. When this time passes, the journal is
125 	written. The journal is also written immediately if the FLUSH
149 	Encrypt the journal using given algorithm to make sure that the
150 	attacker can't read the journal. You can use a block cipher here
154 	The journal contains history of last writes to the block device,
155 	an attacker reading the journal could see the last sector numbers
158 	situation, you can encrypt the journal.
161 	Protect sector numbers in the journal from accidental or malicious
167 	mode, the integrity of journal entries is checked when replaying
168 	the journal. Thus, modified sector number would be detected at
197 	  copy sectors from one journal section to another journal section
210 The journal mode (D/J), buffer_sectors, journal_watermark, commit_time and
243 	* the number of journal sections
254 		- journal area contains the bitmap of dirty
258 * journal
259 	The journal is divided into sections, each section contains:
261 	* metadata area (4kiB), it contains journal entries
263 	  - every journal entry contains:
274 		  numbers in the journal section, to protect against a
276 		  numbers in the journal.
279 	* data area (the size is variable; it depends on how many journal
285 		  the journal entry)
288 	To test if the whole journal section was written correctly, every
289 	512-byte sector of the journal ends with 8-byte commit id. If the
290 	commit id matches on all sectors in a journal section, then it is