1 .\" Copyright (c) 2007 The DragonFly Project. All rights reserved.
3 .\" This code is derived from software contributed to The DragonFly Project
4 .\" by Matthew Dillon <dillon@backplane.com>
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33 .\" $DragonFly: src/sbin/hammer/hammer.8,v 1.58 2008/11/13 02:04:27 dillon Exp $
40 .Nd HAMMER file system utility
47 .Op Fl C Ar cachesize Ns Op Ns Cm \&: Ns Ar readahead
50 .\" .Op Fl s Ar linkpath
57 This manual page documents the
59 utility which provides miscellaneous functions related to managing a
62 For a general introduction to the
64 file system, its features, and
65 examples on how to set up and maintain one, see
68 The options are as follows:
69 .Bl -tag -width indent
73 Tell the mirror commands to use a 2-way protocol, which allows
74 automatic negotiation of transaction id ranges.
75 This option is automatically enabled by the
81 will not attempt to break-up large initial bulk transfers into smaller pieces.
82 This can save time but if the link is lost in the middle of the
83 initial bulk transfer you will have to start over from scratch.
85 Specify a bandwidth limit in bytes per second for mirroring streams.
86 This option is typically used to prevent batch mirroring operations from
87 loading down the machine.
88 The bandwidth may be suffixed with
92 to specify values in kilobytes, megabytes, and gigabytes per second.
93 If no suffix is specified, bytes per second is assumed.
94 .It Fl C Ar cachesize Ns Op Ns Cm \&: Ns Ar readahead
95 Set the memory cache size for any raw
102 for megabytes is allowed,
103 else the cache size is specified in bytes.
105 The read-behind/read-ahead defaults to 4
109 This option is typically only used with diagnostic commands
110 as kernel-supported commands will use the kernel's buffer cache.
111 .It Fl c Ar cyclefile
112 When pruning and reblocking you can instruction
114 to start at the object id stored in the specified file.
115 If the file does not exist
117 will start at the beginning.
121 specific period of time and is unable to complete the operation it will
122 write out the current object id so the next run can pick up where it left off.
125 runs to completion it will delete
128 Specify the volumes making up a
132 is a colon-separated list of devices, each specifying a
136 When maintaining a streaming mirroring this option specifies the
137 minimum delay after a batch ends before the next batch is allowed
139 The default is five seconds.
141 This passes the -p <port> option to ssh when using a remote
142 specification for the source and/or destination.
144 Decrease verboseness.
145 May be specified multiple times.
147 Specify recursion for those commands which support it.
149 When pruning and reblocking you can tell the utility to stop after a
150 certain period of time.
151 This option is used along with the
153 option to prune or reblock a portion of the file system incrementally.
155 Increase verboseness.
156 May be specified multiple times.
158 Force "yes" for any interactive question.
161 The commands are as follows:
162 .Bl -tag -width indent
163 .\" ==== synctid ====
164 .It Cm synctid Ar filesystem Op Cm quick
165 Generates a guaranteed, formal 64 bit transaction id representing the
166 current state of the specified
169 The file system will be synced to the media.
173 keyword is specified the file system will be soft-synced, meaning that a
174 crash might still undo the state of the file system as of the transaction
175 id returned but any new modifications will occur after the returned
176 transaction id as expected.
178 This operation does not create a snapshot.
179 It is meant to be used
180 to track temporary fine-grained changes to a subset of files and
181 will only remain valid for
183 snapshot access purposes for the
185 period configured for the PFS.
186 If you desire a real snapshot then the
188 directive may be what you are looking for.
190 .It Cm bstats Op Ar interval
193 B-tree statistics until interrupted.
196 seconds between each display.
197 The default interval is one second.
198 .\" ==== iostats ====
199 .It Cm iostats Op Ar interval
203 statistics until interrupted.
206 seconds between each display.
207 The default interval is one second.
208 .\" ==== history ====
209 .It Cm history Ar path ...
210 Show the modification history for
212 file's inode and data.
213 .\" ==== blockmap ====
215 Dump the blockmap for the file system.
218 blockmap is two-layer
219 blockmap representing the maximum possible file system size of 1 Exabyte.
220 Needless to say the second layer is only present for blocks which exist.
222 blockmap represents 8-Megabyte blocks, called big-blocks.
223 Each big-block has an append
224 point, a free byte count, and a typed zone id which allows content to be
225 reverse engineered to some degree.
229 allocations essentially appended to a selected big-block using
230 the append offset and deducted from the free byte count.
231 When space is freed the free byte count is adjusted but
233 does not track holes in big-blocks for reallocation.
234 A big-block must be completely freed, either
235 through normal file system operations or through reblocking, before
238 Data blocks can be shared by deducting the space used from the free byte
239 count for each shared references, though
241 does not yet make use of this feature.
242 This means the free byte count can legally go negative.
244 This command needs the
248 .It Cm show Op Ar lo Ns Cm \&: Ns Ar objid
250 By default this command will validate all B-Tree
251 linkages and CRCs, including data CRCs, and will report the most verbose
252 information it can dig up.
253 Any errors will show up with a
255 in column 1 along with various
258 If you specify a localization and object id field,
259 .Ar lo Ns Cm \&: Ns Ar objid ,
261 search for the key printing nodes as it recurses down, and then
262 will iterate forwards.
266 the command will report less information about the inode contents.
270 the command will not report the content of the inode or other typed
275 the command will not report volume header information, big-block fill
276 ratios, mirror transaction ids, or report or check data CRCs.
277 B-tree CRCs and linkages are still checked.
279 This command needs the
282 .\" ==== show-undo ====
288 This command needs the
292 .\" Dump the B-tree, record, large-data, and small-data blockmaps, showing
293 .\" physical block assignments and free space percentages.
294 .\" ==== namekey1 ====
295 .It Cm namekey1 Ar filename
298 64 bit directory hash for the specified file name, using
299 the original directory hash algorithm in version 1 of the file system.
300 The low 32 bits are used as an iterator for hash collisions and will be
302 .\" ==== namekey2 ====
303 .It Cm namekey2 Ar filename
306 64 bit directory hash for the specified file name, using
307 the new directory hash algorithm in version 2 of the file system.
308 The low 32 bits are still used as an iterator but will start out containing
309 part of the hash key.
310 .\" ==== namekey32 ====
311 .It Cm namekey32 Ar filename
312 Generate the top 32 bits of a
314 64 bit directory hash for the specified file name.
317 Shows extended information about all the mounted
320 At the moment volume identification, big-blocks information, space and
321 and pseudo-filesystem (PFS) details are shown.
322 .\" ==== cleanup ====
323 .It Cm cleanup Op Ar filesystem ...
324 This is a meta-command which executes snapshot, prune, rebalance and reblock
325 commands on the specified
330 is specified this command will clean-up all
332 file systems in use, including PFS's.
333 To do this it will scan all
337 mounts, extract PFS id's, and clean-up each PFS found.
339 This command will access a snapshots
340 directory and a configuration file for each
342 creating them if necessary.
343 .Bl -tag -width indent
344 .It Nm HAMMER No version 2-
345 The configuration file is
347 in the snapshots directory which defaults to
348 .Pa <pfs>/snapshots .
349 .It Nm HAMMER No version 3+
350 The configuration file is saved in file system meta-data, see
353 The snapshots directory defaults to
354 .Pa /var/hammer/<pfs>
355 .Pa ( /var/hammer/root
359 The format of the configuration file is:
360 .Bd -literal -offset indent
361 snapshots <period> <retention-time> [any]
362 prune <period> <max-runtime>
363 rebalance <period> <max-runtime>
364 reblock <period> <max-runtime>
365 recopy <period> <max-runtime>
369 .Bd -literal -offset indent
370 snapshots 1d 60d # 0d 0d for PFS /tmp, /var/tmp, /usr/obj
377 Time is given with a suffix of
383 meaning day, hour, minute and second.
387 directive has a period of 0 and a retention time of 0
388 then snapshot generation is disabled, removal of old snapshots are
389 disabled, and prunes will use
390 .Cm prune-everything .
393 directive has a period of 0 but a non-zero retention time
394 then this command will not create any new snapshots but will remove old
395 snapshots it finds based on the retention time.
397 By default only snapshots in the form
398 .Ql snap- Ns Ar yyyymmdd Ns Op - Ns Ar HHMM
402 directive is specified as a third argument on the
404 config line then any softlink of the form
405 .Ql *- Ns Ar yyyymmdd Ns Op - Ns Ar HHMM
407 .Ql *. Ns Ar yyyymmdd Ns Op - Ns Ar HHMM
410 A prune max-runtime of 0 means unlimited.
412 If period hasn't passed since the previous
415 For example a day has passed when midnight is passed (localtime).
423 The default configuration file will create a daily snapshot, do a daily
424 pruning, rebalancing and reblocking run and a monthly recopy run.
425 Reblocking is defragmentation with a level of 95%,
426 and recopy is full defragmentation.
428 By default prune and rebalance operations are time limited to 5 minutes,
429 reblock operations to a bit over 5 minutes,
430 and recopy operations to a bit over 10 minutes.
431 Reblocking and recopy runs are each broken down into four separate functions:
432 btree, inodes, dirs and data.
433 Each function is time limited to the time given in the configuration file,
434 but the btree, inodes and dirs functions usually does not take very long time,
435 full defragmentation is always used for these three functions.
436 Also note that this directive will by default disable snapshots on
443 The defaults may be adjusted by modifying the configuration file.
444 The pruning and reblocking commands automatically maintain a cyclefile
445 for incremental operation.
446 If you interrupt (^C) the program the cyclefile will be updated,
448 may continue to run in the background for a few seconds until the
450 ioctl detects the interrupt.
453 PFS option can be set to use another location for the snapshots directory.
455 Work on this command is still in progress.
457 An ability to remove snapshots dynamically as the
458 file system becomes full.
460 .It Cm config Op Ar filesystem Op Ar configfile
463 If zero or one arguments are specified this function dumps the current
464 configuration file to stdout.
465 Zero arguments specifies the PFS containing the current directory.
466 This configuration file is stored in file system meta-data.
467 If two arguments are specified this function installs a new config file.
471 versions less than 3 the configuration file is by default stored in
472 .Pa <pfs>/snapshots/config ,
473 but in all later versions the configuration file is stored in file system
475 .\" ==== viconfig ====
476 .It Cm viconfig Op Ar filesystem
479 Edit the configuration file and reinstall into file system meta-data when done.
480 Zero arguments specifies the PFS containing the current directory.
481 .\" ==== volume-add ====
482 .It Cm volume-add Ar device Ar filesystem
483 This command will format
485 and add all of its space to
489 All existing data contained on
491 will be destroyed by this operation!
496 file system, formatting will be denied.
497 You can overcome this sanity check
500 to erase the beginning sectors of the device.
501 Also remember that you have to specify
503 together with any other device that make up the file system,
508 .\" ==== volume-del ====
509 .It Cm volume-del Ar device Ar filesystem
510 This command will remove volume
515 Remember that you have to remove
517 from the colon-separated list in
521 .\" ==== snapshot ====
522 .It Cm snapshot Oo Ar filesystem Oc Ar snapshot-dir
523 .It Cm snapshot Ar filesystem Ar snapshot-dir Op Ar note
524 Takes a snapshot of the file system either explicitly given by
526 or implicitly derived from the
528 argument and creates a symlink in the directory provided by
530 pointing to the snapshot.
533 is not a directory, it is assumed to be a format string passed to
535 with the current time as parameter.
538 refers to an existing directory, a default format string of
540 is assumed and used as name for the newly created symlink.
542 Snapshot is a per PFS operation, so a
544 file system and each PFS in it have to be snapshot separately.
546 Example, assuming that
554 are file systems on their own, the following invocations:
555 .Bd -literal -offset indent
556 hammer snapshot /mysnapshots
558 hammer snapshot /mysnapshots/%Y-%m-%d
560 hammer snapshot /obj /mysnapshots/obj-%Y-%m-%d
562 hammer snapshot /usr /my/snaps/usr "note"
565 Would create symlinks similar to:
566 .Bd -literal -offset indent
567 /mysnapshots/snap-20080627-1210 -> /@@0x10d2cd05b7270d16
569 /mysnapshots/2008-06-27 -> /@@0x10d2cd05b7270d16
571 /mysnapshots/obj-2008-06-27 -> /obj@@0x10d2cd05b7270d16
573 /my/snaps/usr/snap-20080627-1210 -> /usr@@0x10d2cd05b7270d16
578 version 3+ file system the snapshot is also recorded in file system meta-data
579 along with the optional
585 .It Cm snap Ar path Op Ar note
588 Create a snapshot for the PFS containing
590 and create a snapshot softlink.
591 If the path specified is a
592 directory a standard snapshot softlink will be created in the directory.
593 The snapshot softlink points to the base of the mounted PFS.
594 .It Cm snaplo Ar path Op Ar note
597 Create a snapshot for the PFS containing
599 and create a snapshot softlink.
600 If the path specified is a
601 directory a standard snapshot softlink will be created in the directory.
602 The snapshot softlink points into the directory it is contained in.
603 .It Cm snapq Ar dir Op Ar note
606 Create a snapshot for the PFS containing the specified directory but do
607 not create a softlink.
608 Instead output a path which can be used to access
609 the directory via the snapshot.
611 An absolute or relative path may be specified.
612 The path will be used as-is as a prefix in the path output to stdout.
614 snap and snapshot directives the snapshot transaction id will be registered
615 in the file system meta-data.
616 .It Cm snaprm Bro Ar path | transid Brc Ar ...
619 Remove a snapshot given its softlink or transaction id.
620 If specifying a transaction id
621 the snapshot is removed from file system meta-data but you are responsible
622 for removing any related softlinks.
623 .It Cm snapls Op Ar path ...
626 Dump the snapshot meta-data for PFSs containing each
628 listing all available snapshots and their notes.
629 If no arguments are specified snapshots for the PFS containing the
630 current directory are listed.
631 This is the definitive list of snapshots for the file system.
633 .It Cm prune Ar softlink-dir
634 Prune the file system based on previously created snapshot softlinks.
635 Pruning is the act of deleting file system history.
638 command will delete file system history such that
639 the file system state is retained for the given snapshots,
640 and all history after the latest snapshot.
641 By setting the per PFS parameter
643 history is guaranteed to be saved at least this time interval.
644 All other history is deleted.
646 The target directory is expected to contain softlinks pointing to
647 snapshots of the file systems you wish to retain.
648 The directory is scanned non-recursively and the mount points and
649 transaction ids stored in the softlinks are extracted and sorted.
650 The file system is then explicitly pruned according to what is found.
651 Cleaning out portions of the file system is as simple as removing a
652 snapshot softlink and then running the
656 As a safety measure pruning only occurs if one or more softlinks are found
659 snapshot id extension.
660 Currently the scanned softlink directory must contain softlinks pointing
664 The softlinks may specify absolute or relative paths.
665 Softlinks must use 20-character
667 transaction ids, as might be returned from
668 .Nm Cm synctid Ar filesystem .
670 Pruning is a per PFS operation, so a
672 file system and each PFS in it have to be pruned separately.
674 Note that pruning a file system may not immediately free-up space,
675 though typically some space will be freed if a large number of records are
677 The file system must be reblocked to completely recover all available space.
679 Example, lets say your that you didn't set
681 and snapshot directory contains the following links:
682 .Bd -literal -offset indent
683 lrwxr-xr-x 1 root wheel 29 May 31 17:57 snap1 ->
684 /usr/obj/@@0x10d2cd05b7270d16
686 lrwxr-xr-x 1 root wheel 29 May 31 17:58 snap2 ->
687 /usr/obj/@@0x10d2cd13f3fde98f
689 lrwxr-xr-x 1 root wheel 29 May 31 17:59 snap3 ->
690 /usr/obj/@@0x10d2cd222adee364
693 If you were to run the
695 command on this directory, then the
698 mount will be pruned to retain the above three snapshots.
699 In addition, history for modifications made to the file system older than
700 the oldest snapshot will be destroyed and history for potentially fine-grained
701 modifications made to the file system more recently than the most recent
702 snapshot will be retained.
704 If you then delete the
706 softlink and rerun the
709 history for modifications pertaining to that snapshot would be destroyed.
713 file system versions 3+ this command also scans the snapshots stored
714 in the file system meta-data and includes them in the prune.
715 .\" ==== prune-everything ====
716 .It Cm prune-everything Ar filesystem
717 This command will remove all historical records from the file system.
718 This directive is not normally used on a production system.
720 This command does not remove snapshot softlinks but will delete all
721 snapshots recorded in file system meta-data (for file system version 3+).
722 The user is responsible for deleting any softlinks.
723 .\" ==== rebalance ====
724 .It Cm rebalance Ar filesystem Op Ar saturation_percentage
725 This command will rebalance the B-tree, nodes with small number of
726 elements will be combined and element counts will be smoothed out
729 The saturation percentage is between 50% and 100%.
730 The default is 75% (the
732 suffix is not needed).
733 .\" ==== reblock* ====
734 .It Cm reblock Ar filesystem Op Ar fill_percentage
735 .It Cm reblock-btree Ar filesystem Op Ar fill_percentage
736 .It Cm reblock-inodes Ar filesystem Op Ar fill_percentage
737 .It Cm reblock-dirs Ar filesystem Op Ar fill_percentage
738 .It Cm reblock-data Ar filesystem Op Ar fill_percentage
739 Attempt to defragment and free space for reuse by reblocking a live
742 Big-blocks cannot be reused by
744 until they are completely free.
745 This command also has the effect of reordering all elements, effectively
746 defragmenting the file system.
748 The default fill percentage is 100% and will cause the file system to be
749 completely defragmented.
750 All specified element types will be reallocated and rewritten.
751 If you wish to quickly free up space instead try specifying
752 a smaller fill percentage, such as 90% or 80% (the
754 suffix is not needed).
756 Since this command may rewrite the entire contents of the disk it is
757 best to do it incrementally from a
763 options to limit the run time.
764 The file system would thus be defragmented over long period of time.
766 It is recommended that separate invocations be used for each data type.
767 B-tree nodes, inodes, and directories are typically the most important
768 elements needing defragmentation.
769 Data can be defragmented over a longer period of time.
771 Reblocking is a per PFS operation, so a
773 file system and each PFS in it have to be reblocked separately.
774 .\" ==== pfs-status ====
775 .It Cm pfs-status Ar dirpath ...
776 Retrieve the mirroring configuration parameters for the specified
778 file systems or pseudo-filesystems (PFS's).
779 .\" ==== pfs-master ====
780 .It Cm pfs-master Ar dirpath Op Ar options
781 Create a pseudo-filesystem (PFS) inside a
784 Up to 65535 such file systems can be created.
785 Each PFS uses an independent inode numbering space making it suitable
786 for use as a replication source or target.
790 directive creates a PFS that you can read, write, and use as a mirroring
793 It is recommended to use a
795 mount to access a PFS, for more information see
797 .\" ==== pfs-slave ====
798 .It Cm pfs-slave Ar dirpath Op Ar options
799 Create a pseudo-filesystem (PFS) inside a
802 Up to 65535 such file systems can be created.
803 Each PFS uses an independent inode numbering space making it suitable
804 for use as a replication source or target.
808 directive creates a PFS that you can use as a mirroring target.
809 You will not be able to access a slave PFS until you have completed the
810 first mirroring operation with it as the target (its root directory will
811 not exist until then).
813 Access to the pfs-slave via the special softlink, as described in the
818 dynamically modify the snapshot transaction id by returning a dynamic result
823 A PFS can only be truly destroyed with the
826 Removing the softlink will not destroy the underlying PFS.
828 It is recommended to use a
830 mount to access a PFS, for more information see
832 .\" ==== pfs-update ====
833 .It Cm pfs-update Ar dirpath Op Ar options
834 Update the configuration parameters for an existing
836 file system or pseudo-filesystem.
837 Options that may be specified:
838 .Bl -tag -width indent
839 .It Cm sync-beg-tid= Ns Ar 0x16llx
840 This is the automatic snapshot access starting transaction id for
842 This parameter is normally updated automatically by the
846 It is important to note that accessing a mirroring slave
847 with a transaction id greater than the last fully synchronized transaction
848 id can result in an unreliable snapshot since you will be accessing
849 data that is still undergoing synchronization.
851 Manually modifying this field is dangerous and can result in a broken mirror.
852 .It Cm sync-end-tid= Ns Ar 0x16llx
853 This is the current synchronization point for mirroring slaves.
854 This parameter is normally updated automatically by the
858 Manually modifying this field is dangerous and can result in a broken mirror.
859 .It Cm shared-uuid= Ns Ar uuid
860 Set the shared UUID for this file system.
861 All mirrors must have the same shared UUID.
862 For safety purposes the
864 directives will refuse to operate on a target with a different shared UUID.
866 Changing the shared UUID on an existing, non-empty mirroring target,
867 including an empty but not completely pruned target,
868 can lead to corruption of the mirroring target.
869 .It Cm unique-uuid= Ns Ar uuid
870 Set the unique UUID for this file system.
871 This UUID should not be used anywhere else,
872 even on exact copies of the file system.
873 .It Cm label= Ns Ar string
874 Set a descriptive label for this file system.
875 .It Cm snapshots= Ns Ar string
876 Specify the snapshots directory which
879 will use to manage this PFS.
880 .Bl -tag -width indent
881 .It Nm HAMMER No version 2-
882 The snapshots directory does not need to be configured for
883 PFS masters and will default to
884 .Pa <pfs>/snapshots .
886 PFS slaves are mirroring slaves so you cannot configure a snapshots
887 directory on the slave itself to be managed by the slave's machine.
888 In fact, the slave will likely have a
890 sub-directory mirrored
891 from the master, but that directory contains the configuration the master
892 is using for its copy of the file system, not the configuration that we
893 want to use for our slave.
895 It is recommended that
896 .Pa <fs>/var/slaves/<name>
897 be configured for a PFS slave, where
903 is an appropriate label.
904 .It Nm HAMMER No version 3+
905 The snapshots directory does not need to be configured for PFS masters or
907 The snapshots directory defaults to
908 .Pa /var/hammer/<pfs>
909 .Pa ( /var/hammer/root
913 You can control snapshot retention on your slave independent of the master.
914 .It Cm snapshots-clear
917 directory path for this PFS.
918 .It Cm prune-min= Ns Ar N Ns Cm d
919 .It Cm prune-min= Ns Oo Ar N Ns Cm d/ Oc Ns \
920 Ar hh Ns Op Cm \&: Ns Ar mm Ns Op Cm \&: Ns Ar ss
921 Set the minimum fine-grained data retention period.
923 always retains fine-grained history up to the most recent snapshot.
924 You can extend the retention period further by specifying a non-zero
926 Any snapshot softlinks within the retention period are ignored
927 for the purposes of pruning (the fine grained history is retained).
928 Number of days, hours, minutes and seconds are given as
933 Because the transaction id in the snapshot softlink cannot be used
934 to calculate a timestamp,
936 uses the earlier of the
940 field of the softlink to
941 determine which snapshots fall within the retention period.
942 Users must be sure to retain one of these two fields when manipulating
945 .\" ==== pfs-upgrade ====
946 .It Cm pfs-upgrade Ar dirpath
947 Upgrade a PFS from slave to master operation.
948 The PFS will be rolled back to the current end synchronization transaction id
949 (removing any partial synchronizations), and will then become writable.
953 currently supports only single masters and using
954 this command can easily result in file system corruption
955 if you don't know what you are doing.
957 This directive will refuse to run if any programs have open descriptors
958 in the PFS, including programs chdir'd into the PFS.
959 .\" ==== pfs-downgrade ====
960 .It Cm pfs-downgrade Ar dirpath
961 Downgrade a master PFS from master to slave operation
962 The PFS becomes read-only and access will be locked to its
965 This directive will refuse to run if any programs have open descriptors
966 in the PFS, including programs chdir'd into the PFS.
967 .\" ==== pfs-destroy ====
968 .It Cm pfs-destroy Ar dirpath
969 This permanently destroys a PFS.
971 This directive will refuse to run if any programs have open descriptors
972 in the PFS, including programs chdir'd into the PFS.
973 .\" ==== mirror-read ====
974 .It Cm mirror-read Ar filesystem Op Ar begin-tid
975 Generate a mirroring stream to stdout.
976 The stream ends when the transaction id space has been exhausted.
977 .\" ==== mirror-read-stream ====
978 .It Cm mirror-read-stream Ar filesystem Op Ar begin-tid
979 Generate a mirroring stream to stdout.
980 Upon completion the stream is paused until new data is synced to the
981 master, then resumed.
982 Operation continues until the pipe is broken.
983 .\" ==== mirror-write ====
984 .It Cm mirror-write Ar filesystem
985 Take a mirroring stream on stdin.
987 This command will fail if the
989 configuration field for the two file systems do not match.
991 If the target PFS does not exist this command will ask you whether
992 you want to create a compatible PFS slave for the target or not.
993 .\" ==== mirror-dump ====
999 to dump an ASCII representation of the mirroring stream.
1000 .\" ==== mirror-copy ====
1001 .\".It Cm mirror-copy Ar [[user@]host:]filesystem [[user@]host:]filesystem
1002 .It Cm mirror-copy \
1003 Oo Oo Ar user Ns Cm @ Oc Ns Ar host Ns Cm \&: Oc Ns Ar filesystem \
1004 Oo Oo Ar user Ns Cm @ Oc Ns Ar host Ns Cm \&: Oc Ns Ar filesystem
1005 This is a shortcut which pipes a
1010 If a remote host specification is made the program forks a
1016 on the appropriate host.
1017 The source may be a master or slave PFS, and the target must be a slave PFS.
1019 This command also established full duplex communication and turns on
1020 the two-way protocol feature which automatically negotiates transaction id
1021 ranges without having to use a cyclefile.
1022 If the operation completes successfully the target PFS's
1025 Note that you must re-chdir into the target PFS to see the updated information.
1026 If you do not you will still be in the previous snapshot.
1028 If the target PFS does not exist this command will ask you whether
1029 you want to create a compatible PFS slave for the target or not.
1030 .\" ==== mirror-stream ====
1031 .\".It Cm mirror-stream Ar [[user@]host:]filesystem [[user@]host:]filesystem
1032 .It Cm mirror-stream \
1033 Oo Oo Ar user Ns Cm @ Oc Ns Ar host Ns Cm \&: Oc Ns Ar filesystem \
1034 Oo Oo Ar user Ns Cm @ Oc Ns Ar host Ns Cm \&: Oc Ns Ar filesystem
1035 This command works similarly to
1037 but does not exit after the initial mirroring completes.
1038 The mirroring operation will resume as changes continue to be made to the
1040 The command is commonly used with
1044 options to keep the mirroring target in sync with the source on a continuing
1047 If the pipe is broken the command will automatically retry after sleeping
1049 The time slept will be 15 seconds plus the time given in the
1053 This command also detects the initial-mirroring case and spends some
1054 time scanning the B-Tree to find good break points, allowing the initial
1055 bulk mirroring operation to be broken down into about 20 separate pieces.
1056 This means that the user can kill and restart the operation and it will
1057 not have to start from scratch once it has gotten past the first chunk.
1060 option may be used to disable this feature and perform an initial bulk
1062 .\" ==== version ====
1063 .It Cm version Ar filesystem
1064 This command returns the
1066 file system version for the specified
1068 as well as the range of versions supported in the kernel.
1071 option may be used to remove the summary at the end.
1072 .\" ==== version-upgrade ====
1073 .It Cm version-upgrade Ar filesystem Ar version Op Cm force
1074 This command upgrades the
1079 Once upgraded a file system may not be downgraded.
1080 If you wish to upgrade a file system to a version greater or equal to the
1081 work-in-progress version number you must specify the
1084 Use of WIP versions should be relegated to testing and may require wiping
1085 the file system as development progresses, even though the WIP version might
1089 This command operates on the entire
1091 file system and is not a per PFS operation.
1092 All PFS's will be affected.
1093 .Bl -tag -width indent
1096 default version, first
1101 New directory entry layout.
1102 This version is using a new directory hash key.
1105 New snapshot management, using file system meta-data for saving
1106 configuration file and snapshots (transaction ids etc.).
1107 Also default snapshots directory has changed.
1111 New undo/flush, giving faster sync.
1115 .Sh PSEUDO-FILESYSTEM (PFS) NOTES
1116 The root of a PFS is not hooked into the primary
1118 file system as a directory.
1121 creates a special softlink called
1123 (exactly 10 characters long) in the primary
1127 then modifies the contents of the softlink as read by
1129 and thus what you see with an
1131 command or if you were to
1134 If the PFS is a master the link reflects the current state of the PFS.
1135 If the PFS is a slave the link reflects the last completed snapshot, and the
1136 contents of the link will change when the next snapshot is completed, and
1141 utility employs numerous safeties to reduce user foot-shooting.
1144 directive requires that the target be configured as a slave and that the
1146 field of the mirroring source and target match.
1147 .Sh UPGRADE INSTRUCTIONS HAMMER V1 TO V2
1148 This upgrade changes the way directory entries are stored.
1149 It is possible to upgrade a V1 file system to V2 in place, but
1150 directories created prior to the upgrade will continue to use
1153 Note that the slave mirroring code in the target kernel had bugs in
1154 V1 which can create an incompatible root directory on the slave.
1157 master created after the upgrade with a
1159 slave created prior to the upgrade.
1161 Any directories created after upgrading will use a new layout.
1162 .Sh UPGRADE INSTRUCTIONS HAMMER V2 TO V3
1163 This upgrade adds meta-data elements to the B-Tree.
1164 It is possible to upgrade a V2 file system to V3 in place.
1165 After issuing the upgrade be sure to run a
1168 to perform post-upgrade tasks.
1170 After making this upgrade running a
1175 directory for each PFS mount into
1176 .Pa /var/hammer/<pfs> .
1179 root mount will migrate
1182 .Pa /var/hammer/root .
1183 Migration occurs only once and only if you have not specified
1184 a snapshots directory in the PFS configuration.
1185 If you have specified a snapshots directory in the PFS configuration no
1186 automatic migration will occur.
1188 For slaves, if you desire, you can migrate your snapshots
1189 config to the new location manually and then clear the
1190 snapshot directory configuration in the slave PFS.
1191 The new snapshots hierarchy is designed to work with
1192 both master and slave PFSs equally well.
1194 In addition, the old config file will be moved to file system meta-data,
1195 editable via the new
1199 The old config file will be deleted.
1200 Migration occurs only once.
1202 The V3 file system has new
1204 directives for creating snapshots.
1205 All snapshot directives, including the original, will create
1206 meta-data entries for the snapshots and the pruning code will
1207 automatically incorporate these entries into its list and
1208 expire them the same way it expires softlinks.
1209 If you by accident blow away your snapshot softlinks you can use the
1211 directive to get a definitive list from the file system meta-data and
1212 regenerate them from that list.
1217 to backup file systems your scripts may be using the
1219 directive to generate transaction ids.
1220 This directive does not create a snapshot.
1221 You will have to modify your scripts to use the
1223 directive to generate the linkbuf for the softlink you create, or
1224 use one of the other
1229 directive will continue to work as expected and in V3 it will also
1230 record the snapshot transaction id in file system meta-data.
1231 You may also want to make use of the new
1233 tag for the meta-data.
1236 If you used to remove snapshot softlinks with
1238 you should probably start using the
1240 directive instead to also remove the related meta-data.
1241 The pruning code scans the meta-data so just removing the
1242 softlink is not sufficient.
1243 .Sh UPGRADE INSTRUCTIONS HAMMER V3 TO V4
1244 This upgrade changes undo/flush, giving faster sync.
1245 It is possible to upgrade a V3 file system to V4 in place.
1246 This upgrade reformats the UNDO FIFO (typically 1GB), so upgrade might take
1247 a minute or two depending.
1249 Version 4 allows the UNDO FIFO to be flushed without also having
1250 to flush the volume header, removing 2 of the 4 disk syncs typically
1251 required for an fsync() and removing 1 of the 2 disk syncs typically
1252 required for a flush sequence.
1256 .Bl -tag -width ".It Pa <fs>/var/slaves/<name>" -compact
1257 .It Pa <pfs>/snapshots
1258 default per PFS snapshots directory
1261 .It Pa /var/hammer/<pfs>
1262 default per PFS snapshots directory (not root)
1265 .It Pa /var/hammer/root
1266 default snapshots directory for root directory
1269 .It Pa <snapshots>/config
1276 .It Pa <fs>/var/slaves/<name>
1277 recommended slave PFS snapshots directory
1285 .Xr periodic.conf 5 ,
1286 .Xr mount_hammer 8 ,
1292 utility first appeared in
1295 .An Matthew Dillon Aq dillon@backplane.com
projects / dragonfly.git / blob