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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"
245 Setting a non-zero value enables debugging at various levels.
246 Debug level 1 will record actions at a journal level, relating to journal
247 switches, metadata updates, etc.
248 Debug level 2 will record actions at a higher level, relating to the numbers of
249 entries in journals, access requests, etc.
250 Debug level 3 will record verbose detail, including insertion of I/Os to the
253 The maximum number of seconds a journal is allowed to remain open before
254 switching to a new journal.
256 Force a journal switch when the journal uses more than N% of the free journal
258 .It Li parallel_flushes
259 The number of flush I/O requests to be sent in parallel when flushing the
260 journal to the data provider.
261 .It Li accept_immediately
262 The maximum number of I/O requests accepted at the same time.
263 .It Li parallel_copies
264 The number of copy I/O requests to send in parallel.
265 .It Li record_entries
266 The maximum number of record entries to allow in a single journal.
268 Controls whether entries in a journal will be optimized by combining overlapping
269 I/Os into a single I/O and reordering the entries in a journal.
270 This can be disabled by setting the sysctl to 0.
273 The string and integer information available for the cache level
275 The changeable column shows whether a process with appropriate
276 privilege may change the value.
277 .Bl -column "alloc_failuresXXXXXX" integerXXX -offset indent
278 .It Sy "sysctl name Type Changeable"
279 .It "used integer no"
280 .It "limit integer yes"
281 .It "divisor integer no"
282 .It "switch integer yes"
283 .It "misses integer yes"
284 .It "alloc_failures integer yes"
288 The number of bytes currently allocated to the cache.
290 The maximum number of bytes to be allocated to the cache.
292 Sets the cache size to be used as a proportion of kmem_size.
293 A value of 2 (the default) will cause the cache size to be set to 1/2 of the
296 Force a journal switch when this percentage of cache has been used.
298 The number of cache misses, when data has been read, but was not found in the
300 .It Li alloc_failures
301 The number of times memory failed to be allocated to the cache because the cache
305 The string and integer information available for the statistics level
307 The changeable column shows whether a process with appropriate
308 privilege may change the value.
309 .Bl -column "skipped_bytesXXXXXX" integerXXX -offset indent
310 .It Sy "sysctl name Type Changeable"
311 .It "skipped_bytes integer yes"
312 .It "combined_ios integer yes"
313 .It "switches integer yes"
314 .It "wait_for_copy integer yes"
315 .It "journal_full integer yes"
316 .It "low_mem integer yes"
320 The number of bytes skipped.
322 The number of I/Os which were combined by journal optimization.
324 The number of journal switches.
326 The number of times the journal switch process had to wait for the previous
327 journal copy to complete.
329 The number of times the journal was almost full, forcing a journal switch.
331 The number of times the low_mem hook was called.
346 .An Pawel Jakub Dawidek Aq Mt pjd@FreeBSD.org