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32 .Nd "control utility for journaled devices"
65 utility is used for journal configuration on the given GEOM provider.
66 The Journal and data may be stored on the same provider or on two separate
68 This is block level journaling, not file system level journaling, which means
69 everything gets logged, e.g.\& for file systems, it journals both data and
73 GEOM class can talk to file systems, which allows the use of
75 for file system journaling and to keep file systems in a consistent state.
76 At this time, only UFS file system is supported.
78 To configure journaling on the UFS file system using
80 one should first create a
90 flag which instructs UFS to cooperate with the
93 There are important differences in how journaled UFS works.
94 The most important one is that
98 system calls do not work as expected anymore.
99 To ensure that data is stored on the data provider, the
101 command should be used after calling
103 For the best performance possible, soft-updates should be disabled when
106 It is also safe and recommended to use the
113 is configured on top of
117 providers, it also keeps them in a consistent state, thus
118 automatic synchronization on power failure or system crash may be disabled
123 utility uses on-disk metadata, stored in the provider's last sector,
124 to store all needed information.
125 This could be a problem when an existing file system is converted to use
128 The first argument to
130 indicates an action to be performed:
131 .Bl -tag -width ".Cm status"
135 on the given provider(s).
136 If only one provider is given, both data and journal are stored on the same
138 If two providers are given, the first one will be used as data provider and the
139 second will be used as the journal provider.
141 Additional options include:
142 .Bl -tag -width ".Fl s Ar jsize"
144 Checksum journal records.
146 May be used to convert an existing file system to use
148 but only if the journal will be configured on a separate provider and if the
149 last sector in the data provider is not used by the existing file system.
152 detects that the last sector is used, it will refuse to overwrite it
154 This behavior may be forced by using the
156 flag, which will force
158 to overwrite the last sector.
160 Hardcode provider names in metadata.
162 Specifies size of the journal if only one provider is used for both data and
164 The default is one gigabyte.
165 Size should be chosen based on provider's load, and not on its size;
166 recommended minimum is twice the size of the physical memory installed.
167 It is not recommended to use
169 for small file systems (e.g.: only few gigabytes big).
172 Clear metadata on the given providers.
174 Stop the given provider.
176 Additional options include:
177 .Bl -tag -width ".Fl f"
179 Stop the given provider even if it is opened.
182 Trigger journal switch and enforce sending data to the data provider.
184 Dump metadata stored on the given providers.
199 Additional options include:
200 .Bl -tag -width ".Fl v"
205 Exit status is 0 on success, and 1 if the command fails.
209 based UFS file system and mount it:
210 .Bd -literal -offset indent
213 newfs -J /dev/da0.journal
214 mount -o async /dev/da0.journal /mnt
217 Configure journaling on an existing file system, but only if
219 allows this (i.e., if the last sector is not already used by the file system):
220 .Bd -literal -offset indent
222 gjournal label da0s1d da0s1e && \e
223 tunefs -J enable -n disable da0s1d.journal && \e
224 mount -o async /dev/da0s1d.journal /mnt || \e
225 mount /dev/da0s1d /mnt
228 Gjournal adds the sysctl level kern.geom.journal.
229 The string and integer information available is detailed below.
230 The changeable column shows whether a process with appropriate privilege may
232 .Bl -column "accept_immediatelyXXXXXX" integerXXX -offset indent
233 .It Sy "sysctl name Type Changeable"
234 .It "debug integer yes"
235 .It "switch_time integer yes"
236 .It "force_switch integer yes"
237 .It "parallel_flushes integer yes"
238 .It "accept_immediately integer yes"
239 .It "parallel_copies integer yes"
240 .It "record_entries integer yes"
241 .It "optimize integer yes"
246 Setting a non-zero value enables debugging at various levels.
247 Debug level 1 will record actions at a journal level, relating to journal
248 switches, metadata updates, etc.
249 Debug level 2 will record actions at a higher level, relating to the numbers of
250 entries in journals, access requests, etc.
251 Debug level 3 will record verbose detail, including insertion of I/Os to the
254 The maximum number of seconds a journal is allowed to remain open before
255 switching to a new journal.
257 Force a journal switch when the journal uses more than N% of the free journal
259 .It Li parallel_flushes
260 The number of flush I/O requests to be sent in parallel when flushing the
261 journal to the data provider.
262 .It Li accept_immediately
263 The maximum number of I/O requests accepted at the same time.
264 .It Li parallel_copies
265 The number of copy I/O requests to send in parallel.
266 .It Li record_entries
267 The maximum number of record entries to allow in a single journal.
269 Controls whether entries in a journal will be optimized by combining overlapping
270 I/Os into a single I/O and reordering the entries in a journal.
271 This can be disabled by setting the sysctl to 0.
274 The string and integer information available for the cache level
276 The changeable column shows whether a process with appropriate
277 privilege may change the value.
278 .Bl -column "alloc_failuresXXXXXX" integerXXX -offset indent
279 .It Sy "sysctl name Type Changeable"
280 .It "used integer no"
281 .It "limit integer yes"
282 .It "divisor integer no"
283 .It "switch integer yes"
284 .It "misses integer yes"
285 .It "alloc_failures integer yes"
290 The number of bytes currently allocated to the cache.
292 The maximum number of bytes to be allocated to the cache.
294 Sets the cache size to be used as a proportion of kmem_size.
295 A value of 2 (the default) will cause the cache size to be set to 1/2 of the
298 Force a journal switch when this percentage of cache has been used.
300 The number of cache misses, when data has been read, but was not found in the
302 .It Li alloc_failures
303 The number of times memory failed to be allocated to the cache because the cache
307 The string and integer information available for the statistics level
309 The changeable column shows whether a process with appropriate
310 privilege may change the value.
311 .Bl -column "skipped_bytesXXXXXX" integerXXX -offset indent
312 .It Sy "sysctl name Type Changeable"
313 .It "skipped_bytes integer yes"
314 .It "combined_ios integer yes"
315 .It "switches integer yes"
316 .It "wait_for_copy integer yes"
317 .It "journal_full integer yes"
318 .It "low_mem integer yes"
323 The number of bytes skipped.
325 The number of I/Os which were combined by journal optimization.
327 The number of journal switches.
329 The number of times the journal switch process had to wait for the previous
330 journal copy to complete.
332 The number of times the journal was almost full, forcing a journal switch.
334 The number of times the low_mem hook was called.
349 .An Pawel Jakub Dawidek Aq pjd@FreeBSD.org