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 Enable compression for any remote ssh specifications. Unfortunately
161 option has already been reserved for other purposes so we had to use
162 a different letter. This option is typically used with the
163 mirroring directives.
165 Force "yes" for any interactive question.
168 The commands are as follows:
169 .Bl -tag -width indent
170 .\" ==== synctid ====
171 .It Cm synctid Ar filesystem Op Cm quick
172 Generates a guaranteed, formal 64 bit transaction id representing the
173 current state of the specified
176 The file system will be synced to the media.
180 keyword is specified the file system will be soft-synced, meaning that a
181 crash might still undo the state of the file system as of the transaction
182 id returned but any new modifications will occur after the returned
183 transaction id as expected.
185 This operation does not create a snapshot.
186 It is meant to be used
187 to track temporary fine-grained changes to a subset of files and
188 will only remain valid for
190 snapshot access purposes for the
192 period configured for the PFS.
193 If you desire a real snapshot then the
195 directive may be what you are looking for.
197 .It Cm bstats Op Ar interval
200 B-tree statistics until interrupted.
203 seconds between each display.
204 The default interval is one second.
205 .\" ==== iostats ====
206 .It Cm iostats Op Ar interval
210 statistics until interrupted.
213 seconds between each display.
214 The default interval is one second.
215 .\" ==== history ====
216 .It Cm history Ar path ...
217 Show the modification history for
219 file's inode and data.
220 .\" ==== blockmap ====
222 Dump the blockmap for the file system.
225 blockmap is two-layer
226 blockmap representing the maximum possible file system size of 1 Exabyte.
227 Needless to say the second layer is only present for blocks which exist.
229 blockmap represents 8-Megabyte blocks, called big-blocks.
230 Each big-block has an append
231 point, a free byte count, and a typed zone id which allows content to be
232 reverse engineered to some degree.
236 allocations essentially appended to a selected big-block using
237 the append offset and deducted from the free byte count.
238 When space is freed the free byte count is adjusted but
240 does not track holes in big-blocks for reallocation.
241 A big-block must be completely freed, either
242 through normal file system operations or through reblocking, before
245 Data blocks can be shared by deducting the space used from the free byte
246 count for each shared references, though
248 does not yet make use of this feature.
249 This means the free byte count can legally go negative.
251 This command needs the
255 .It Cm show Op Ar lo Ns Cm \&: Ns Ar objid
257 By default this command will validate all B-Tree
258 linkages and CRCs, including data CRCs, and will report the most verbose
259 information it can dig up.
260 Any errors will show up with a
262 in column 1 along with various
265 If you specify a localization and object id field,
266 .Ar lo Ns Cm \&: Ns Ar objid ,
268 search for the key printing nodes as it recurses down, and then
269 will iterate forwards.
273 the command will report less information about the inode contents.
277 the command will not report the content of the inode or other typed
282 the command will not report volume header information, big-block fill
283 ratios, mirror transaction ids, or report or check data CRCs.
284 B-tree CRCs and linkages are still checked.
286 This command needs the
289 .\" ==== show-undo ====
295 This command needs the
299 .\" Dump the B-tree, record, large-data, and small-data blockmaps, showing
300 .\" physical block assignments and free space percentages.
301 .\" ==== namekey1 ====
302 .It Cm namekey1 Ar filename
305 64 bit directory hash for the specified file name, using
306 the original directory hash algorithm in version 1 of the file system.
307 The low 32 bits are used as an iterator for hash collisions and will be
309 .\" ==== namekey2 ====
310 .It Cm namekey2 Ar filename
313 64 bit directory hash for the specified file name, using
314 the new directory hash algorithm in version 2 of the file system.
315 The low 32 bits are still used as an iterator but will start out containing
316 part of the hash key.
317 .\" ==== namekey32 ====
318 .It Cm namekey32 Ar filename
319 Generate the top 32 bits of a
321 64 bit directory hash for the specified file name.
324 Shows extended information about all the mounted
327 At the moment volume identification, big-blocks information, space and
328 and pseudo-filesystem (PFS) details are shown.
329 .\" ==== cleanup ====
330 .It Cm cleanup Op Ar filesystem ...
331 This is a meta-command which executes snapshot, prune, rebalance and reblock
332 commands on the specified
337 is specified this command will clean-up all
339 file systems in use, including PFS's.
340 To do this it will scan all
344 mounts, extract PFS id's, and clean-up each PFS found.
346 This command will access a snapshots
347 directory and a configuration file for each
349 creating them if necessary.
350 .Bl -tag -width indent
351 .It Nm HAMMER No version 2-
352 The configuration file is
354 in the snapshots directory which defaults to
355 .Pa <pfs>/snapshots .
356 .It Nm HAMMER No version 3+
357 The configuration file is saved in file system meta-data, see
360 The snapshots directory defaults to
361 .Pa /var/hammer/<pfs>
362 .Pa ( /var/hammer/root
366 The format of the configuration file is:
367 .Bd -literal -offset indent
368 snapshots <period> <retention-time> [any]
369 prune <period> <max-runtime>
370 rebalance <period> <max-runtime>
371 reblock <period> <max-runtime>
372 recopy <period> <max-runtime>
376 .Bd -literal -offset indent
377 snapshots 1d 60d # 0d 0d for PFS /tmp, /var/tmp, /usr/obj
384 Time is given with a suffix of
390 meaning day, hour, minute and second.
394 directive has a period of 0 and a retention time of 0
395 then snapshot generation is disabled, removal of old snapshots are
396 disabled, and prunes will use
397 .Cm prune-everything .
400 directive has a period of 0 but a non-zero retention time
401 then this command will not create any new snapshots but will remove old
402 snapshots it finds based on the retention time.
404 By default only snapshots in the form
405 .Ql snap- Ns Ar yyyymmdd Ns Op - Ns Ar HHMM
409 directive is specified as a third argument on the
411 config line then any softlink of the form
412 .Ql *- Ns Ar yyyymmdd Ns Op - Ns Ar HHMM
414 .Ql *. Ns Ar yyyymmdd Ns Op - Ns Ar HHMM
417 A prune max-runtime of 0 means unlimited.
419 If period hasn't passed since the previous
422 For example a day has passed when midnight is passed (localtime).
430 The default configuration file will create a daily snapshot, do a daily
431 pruning, rebalancing and reblocking run and a monthly recopy run.
432 Reblocking is defragmentation with a level of 95%,
433 and recopy is full defragmentation.
435 By default prune and rebalance operations are time limited to 5 minutes,
436 reblock operations to a bit over 5 minutes,
437 and recopy operations to a bit over 10 minutes.
438 Reblocking and recopy runs are each broken down into four separate functions:
439 btree, inodes, dirs and data.
440 Each function is time limited to the time given in the configuration file,
441 but the btree, inodes and dirs functions usually does not take very long time,
442 full defragmentation is always used for these three functions.
443 Also note that this directive will by default disable snapshots on
450 The defaults may be adjusted by modifying the configuration file.
451 The pruning and reblocking commands automatically maintain a cyclefile
452 for incremental operation.
453 If you interrupt (^C) the program the cyclefile will be updated,
455 may continue to run in the background for a few seconds until the
457 ioctl detects the interrupt.
460 PFS option can be set to use another location for the snapshots directory.
462 Work on this command is still in progress.
464 An ability to remove snapshots dynamically as the
465 file system becomes full.
467 .It Cm config Op Ar filesystem Op Ar configfile
470 If zero or one arguments are specified this function dumps the current
471 configuration file to stdout.
472 Zero arguments specifies the PFS containing the current directory.
473 This configuration file is stored in file system meta-data.
474 If two arguments are specified this function installs a new config file.
478 versions less than 3 the configuration file is by default stored in
479 .Pa <pfs>/snapshots/config ,
480 but in all later versions the configuration file is stored in file system
482 .\" ==== viconfig ====
483 .It Cm viconfig Op Ar filesystem
486 Edit the configuration file and reinstall into file system meta-data when done.
487 Zero arguments specifies the PFS containing the current directory.
488 .\" ==== volume-add ====
489 .It Cm volume-add Ar device Ar filesystem
490 This command will format
492 and add all of its space to
496 All existing data contained on
498 will be destroyed by this operation!
503 file system, formatting will be denied.
504 You can overcome this sanity check
507 to erase the beginning sectors of the device.
508 Also remember that you have to specify
510 together with any other device that make up the file system,
515 .\" ==== volume-del ====
516 .It Cm volume-del Ar device Ar filesystem
517 This command will remove volume
522 Remember that you have to remove
524 from the colon-separated list in
528 .\" ==== snapshot ====
529 .It Cm snapshot Oo Ar filesystem Oc Ar snapshot-dir
530 .It Cm snapshot Ar filesystem Ar snapshot-dir Op Ar note
531 Takes a snapshot of the file system either explicitly given by
533 or implicitly derived from the
535 argument and creates a symlink in the directory provided by
537 pointing to the snapshot.
540 is not a directory, it is assumed to be a format string passed to
542 with the current time as parameter.
545 refers to an existing directory, a default format string of
547 is assumed and used as name for the newly created symlink.
549 Snapshot is a per PFS operation, so a
551 file system and each PFS in it have to be snapshot separately.
553 Example, assuming that
561 are file systems on their own, the following invocations:
562 .Bd -literal -offset indent
563 hammer snapshot /mysnapshots
565 hammer snapshot /mysnapshots/%Y-%m-%d
567 hammer snapshot /obj /mysnapshots/obj-%Y-%m-%d
569 hammer snapshot /usr /my/snaps/usr "note"
572 Would create symlinks similar to:
573 .Bd -literal -offset indent
574 /mysnapshots/snap-20080627-1210 -> /@@0x10d2cd05b7270d16
576 /mysnapshots/2008-06-27 -> /@@0x10d2cd05b7270d16
578 /mysnapshots/obj-2008-06-27 -> /obj@@0x10d2cd05b7270d16
580 /my/snaps/usr/snap-20080627-1210 -> /usr@@0x10d2cd05b7270d16
585 version 3+ file system the snapshot is also recorded in file system meta-data
586 along with the optional
592 .It Cm snap Ar path Op Ar note
595 Create a snapshot for the PFS containing
597 and create a snapshot softlink.
598 If the path specified is a
599 directory a standard snapshot softlink will be created in the directory.
600 The snapshot softlink points to the base of the mounted PFS.
601 .It Cm snaplo Ar path Op Ar note
604 Create a snapshot for the PFS containing
606 and create a snapshot softlink.
607 If the path specified is a
608 directory a standard snapshot softlink will be created in the directory.
609 The snapshot softlink points into the directory it is contained in.
610 .It Cm snapq Ar dir Op Ar note
613 Create a snapshot for the PFS containing the specified directory but do
614 not create a softlink.
615 Instead output a path which can be used to access
616 the directory via the snapshot.
618 An absolute or relative path may be specified.
619 The path will be used as-is as a prefix in the path output to stdout.
621 snap and snapshot directives the snapshot transaction id will be registered
622 in the file system meta-data.
623 .It Cm snaprm Bro Ar path | transid Brc Ar ...
626 Remove a snapshot given its softlink or transaction id.
627 If specifying a transaction id
628 the snapshot is removed from file system meta-data but you are responsible
629 for removing any related softlinks.
630 .It Cm snapls Op Ar path ...
633 Dump the snapshot meta-data for PFSs containing each
635 listing all available snapshots and their notes.
636 If no arguments are specified snapshots for the PFS containing the
637 current directory are listed.
638 This is the definitive list of snapshots for the file system.
640 .It Cm prune Ar softlink-dir
641 Prune the file system based on previously created snapshot softlinks.
642 Pruning is the act of deleting file system history.
645 command will delete file system history such that
646 the file system state is retained for the given snapshots,
647 and all history after the latest snapshot.
648 By setting the per PFS parameter
650 history is guaranteed to be saved at least this time interval.
651 All other history is deleted.
653 The target directory is expected to contain softlinks pointing to
654 snapshots of the file systems you wish to retain.
655 The directory is scanned non-recursively and the mount points and
656 transaction ids stored in the softlinks are extracted and sorted.
657 The file system is then explicitly pruned according to what is found.
658 Cleaning out portions of the file system is as simple as removing a
659 snapshot softlink and then running the
663 As a safety measure pruning only occurs if one or more softlinks are found
666 snapshot id extension.
667 Currently the scanned softlink directory must contain softlinks pointing
671 The softlinks may specify absolute or relative paths.
672 Softlinks must use 20-character
674 transaction ids, as might be returned from
675 .Nm Cm synctid Ar filesystem .
677 Pruning is a per PFS operation, so a
679 file system and each PFS in it have to be pruned separately.
681 Note that pruning a file system may not immediately free-up space,
682 though typically some space will be freed if a large number of records are
684 The file system must be reblocked to completely recover all available space.
686 Example, lets say your that you didn't set
688 and snapshot directory contains the following links:
689 .Bd -literal -offset indent
690 lrwxr-xr-x 1 root wheel 29 May 31 17:57 snap1 ->
691 /usr/obj/@@0x10d2cd05b7270d16
693 lrwxr-xr-x 1 root wheel 29 May 31 17:58 snap2 ->
694 /usr/obj/@@0x10d2cd13f3fde98f
696 lrwxr-xr-x 1 root wheel 29 May 31 17:59 snap3 ->
697 /usr/obj/@@0x10d2cd222adee364
700 If you were to run the
702 command on this directory, then the
705 mount will be pruned to retain the above three snapshots.
706 In addition, history for modifications made to the file system older than
707 the oldest snapshot will be destroyed and history for potentially fine-grained
708 modifications made to the file system more recently than the most recent
709 snapshot will be retained.
711 If you then delete the
713 softlink and rerun the
716 history for modifications pertaining to that snapshot would be destroyed.
720 file system versions 3+ this command also scans the snapshots stored
721 in the file system meta-data and includes them in the prune.
722 .\" ==== prune-everything ====
723 .It Cm prune-everything Ar filesystem
724 This command will remove all historical records from the file system.
725 This directive is not normally used on a production system.
727 This command does not remove snapshot softlinks but will delete all
728 snapshots recorded in file system meta-data (for file system version 3+).
729 The user is responsible for deleting any softlinks.
730 .\" ==== rebalance ====
731 .It Cm rebalance Ar filesystem Op Ar saturation_percentage
732 This command will rebalance the B-tree, nodes with small number of
733 elements will be combined and element counts will be smoothed out
736 The saturation percentage is between 50% and 100%.
737 The default is 75% (the
739 suffix is not needed).
740 .\" ==== reblock* ====
741 .It Cm reblock Ar filesystem Op Ar fill_percentage
742 .It Cm reblock-btree Ar filesystem Op Ar fill_percentage
743 .It Cm reblock-inodes Ar filesystem Op Ar fill_percentage
744 .It Cm reblock-dirs Ar filesystem Op Ar fill_percentage
745 .It Cm reblock-data Ar filesystem Op Ar fill_percentage
746 Attempt to defragment and free space for reuse by reblocking a live
749 Big-blocks cannot be reused by
751 until they are completely free.
752 This command also has the effect of reordering all elements, effectively
753 defragmenting the file system.
755 The default fill percentage is 100% and will cause the file system to be
756 completely defragmented.
757 All specified element types will be reallocated and rewritten.
758 If you wish to quickly free up space instead try specifying
759 a smaller fill percentage, such as 90% or 80% (the
761 suffix is not needed).
763 Since this command may rewrite the entire contents of the disk it is
764 best to do it incrementally from a
770 options to limit the run time.
771 The file system would thus be defragmented over long period of time.
773 It is recommended that separate invocations be used for each data type.
774 B-tree nodes, inodes, and directories are typically the most important
775 elements needing defragmentation.
776 Data can be defragmented over a longer period of time.
778 Reblocking is a per PFS operation, so a
780 file system and each PFS in it have to be reblocked separately.
781 .\" ==== pfs-status ====
782 .It Cm pfs-status Ar dirpath ...
783 Retrieve the mirroring configuration parameters for the specified
785 file systems or pseudo-filesystems (PFS's).
786 .\" ==== pfs-master ====
787 .It Cm pfs-master Ar dirpath Op Ar options
788 Create a pseudo-filesystem (PFS) inside a
791 Up to 65535 such file systems can be created.
792 Each PFS uses an independent inode numbering space making it suitable
793 for use as a replication source or target.
797 directive creates a PFS that you can read, write, and use as a mirroring
800 It is recommended to use a
802 mount to access a PFS, for more information see
804 .\" ==== pfs-slave ====
805 .It Cm pfs-slave Ar dirpath Op Ar options
806 Create a pseudo-filesystem (PFS) inside a
809 Up to 65535 such file systems can be created.
810 Each PFS uses an independent inode numbering space making it suitable
811 for use as a replication source or target.
815 directive creates a PFS that you can use as a mirroring target.
816 You will not be able to access a slave PFS until you have completed the
817 first mirroring operation with it as the target (its root directory will
818 not exist until then).
820 Access to the pfs-slave via the special softlink, as described in the
825 dynamically modify the snapshot transaction id by returning a dynamic result
830 A PFS can only be truly destroyed with the
833 Removing the softlink will not destroy the underlying PFS.
835 It is recommended to use a
837 mount to access a PFS, for more information see
839 .\" ==== pfs-update ====
840 .It Cm pfs-update Ar dirpath Op Ar options
841 Update the configuration parameters for an existing
843 file system or pseudo-filesystem.
844 Options that may be specified:
845 .Bl -tag -width indent
846 .It Cm sync-beg-tid= Ns Ar 0x16llx
847 This is the automatic snapshot access starting transaction id for
849 This parameter is normally updated automatically by the
853 It is important to note that accessing a mirroring slave
854 with a transaction id greater than the last fully synchronized transaction
855 id can result in an unreliable snapshot since you will be accessing
856 data that is still undergoing synchronization.
858 Manually modifying this field is dangerous and can result in a broken mirror.
859 .It Cm sync-end-tid= Ns Ar 0x16llx
860 This is the current synchronization point for mirroring slaves.
861 This parameter is normally updated automatically by the
865 Manually modifying this field is dangerous and can result in a broken mirror.
866 .It Cm shared-uuid= Ns Ar uuid
867 Set the shared UUID for this file system.
868 All mirrors must have the same shared UUID.
869 For safety purposes the
871 directives will refuse to operate on a target with a different shared UUID.
873 Changing the shared UUID on an existing, non-empty mirroring target,
874 including an empty but not completely pruned target,
875 can lead to corruption of the mirroring target.
876 .It Cm unique-uuid= Ns Ar uuid
877 Set the unique UUID for this file system.
878 This UUID should not be used anywhere else,
879 even on exact copies of the file system.
880 .It Cm label= Ns Ar string
881 Set a descriptive label for this file system.
882 .It Cm snapshots= Ns Ar string
883 Specify the snapshots directory which
886 will use to manage this PFS.
887 .Bl -tag -width indent
888 .It Nm HAMMER No version 2-
889 The snapshots directory does not need to be configured for
890 PFS masters and will default to
891 .Pa <pfs>/snapshots .
893 PFS slaves are mirroring slaves so you cannot configure a snapshots
894 directory on the slave itself to be managed by the slave's machine.
895 In fact, the slave will likely have a
897 sub-directory mirrored
898 from the master, but that directory contains the configuration the master
899 is using for its copy of the file system, not the configuration that we
900 want to use for our slave.
902 It is recommended that
903 .Pa <fs>/var/slaves/<name>
904 be configured for a PFS slave, where
910 is an appropriate label.
911 .It Nm HAMMER No version 3+
912 The snapshots directory does not need to be configured for PFS masters or
914 The snapshots directory defaults to
915 .Pa /var/hammer/<pfs>
916 .Pa ( /var/hammer/root
920 You can control snapshot retention on your slave independent of the master.
921 .It Cm snapshots-clear
924 directory path for this PFS.
925 .It Cm prune-min= Ns Ar N Ns Cm d
926 .It Cm prune-min= Ns Oo Ar N Ns Cm d/ Oc Ns \
927 Ar hh Ns Op Cm \&: Ns Ar mm Ns Op Cm \&: Ns Ar ss
928 Set the minimum fine-grained data retention period.
930 always retains fine-grained history up to the most recent snapshot.
931 You can extend the retention period further by specifying a non-zero
933 Any snapshot softlinks within the retention period are ignored
934 for the purposes of pruning (the fine grained history is retained).
935 Number of days, hours, minutes and seconds are given as
940 Because the transaction id in the snapshot softlink cannot be used
941 to calculate a timestamp,
943 uses the earlier of the
947 field of the softlink to
948 determine which snapshots fall within the retention period.
949 Users must be sure to retain one of these two fields when manipulating
952 .\" ==== pfs-upgrade ====
953 .It Cm pfs-upgrade Ar dirpath
954 Upgrade a PFS from slave to master operation.
955 The PFS will be rolled back to the current end synchronization transaction id
956 (removing any partial synchronizations), and will then become writable.
960 currently supports only single masters and using
961 this command can easily result in file system corruption
962 if you don't know what you are doing.
964 This directive will refuse to run if any programs have open descriptors
965 in the PFS, including programs chdir'd into the PFS.
966 .\" ==== pfs-downgrade ====
967 .It Cm pfs-downgrade Ar dirpath
968 Downgrade a master PFS from master to slave operation
969 The PFS becomes read-only and access will be locked to its
972 This directive will refuse to run if any programs have open descriptors
973 in the PFS, including programs chdir'd into the PFS.
974 .\" ==== pfs-destroy ====
975 .It Cm pfs-destroy Ar dirpath
976 This permanently destroys a PFS.
978 This directive will refuse to run if any programs have open descriptors
979 in the PFS, including programs chdir'd into the PFS.
980 .\" ==== mirror-read ====
981 .It Cm mirror-read Ar filesystem Op Ar begin-tid
982 Generate a mirroring stream to stdout.
983 The stream ends when the transaction id space has been exhausted.
984 .\" ==== mirror-read-stream ====
985 .It Cm mirror-read-stream Ar filesystem Op Ar begin-tid
986 Generate a mirroring stream to stdout.
987 Upon completion the stream is paused until new data is synced to the
988 master, then resumed.
989 Operation continues until the pipe is broken.
990 .\" ==== mirror-write ====
991 .It Cm mirror-write Ar filesystem
992 Take a mirroring stream on stdin.
994 This command will fail if the
996 configuration field for the two file systems do not match.
998 If the target PFS does not exist this command will ask you whether
999 you want to create a compatible PFS slave for the target or not.
1000 .\" ==== mirror-dump ====
1006 to dump an ASCII representation of the mirroring stream.
1007 .\" ==== mirror-copy ====
1008 .\".It Cm mirror-copy Ar [[user@]host:]filesystem [[user@]host:]filesystem
1009 .It Cm mirror-copy \
1010 Oo Oo Ar user Ns Cm @ Oc Ns Ar host Ns Cm \&: Oc Ns Ar filesystem \
1011 Oo Oo Ar user Ns Cm @ Oc Ns Ar host Ns Cm \&: Oc Ns Ar filesystem
1012 This is a shortcut which pipes a
1017 If a remote host specification is made the program forks a
1023 on the appropriate host.
1024 The source may be a master or slave PFS, and the target must be a slave PFS.
1026 This command also established full duplex communication and turns on
1027 the two-way protocol feature which automatically negotiates transaction id
1028 ranges without having to use a cyclefile.
1029 If the operation completes successfully the target PFS's
1032 Note that you must re-chdir into the target PFS to see the updated information.
1033 If you do not you will still be in the previous snapshot.
1035 If the target PFS does not exist this command will ask you whether
1036 you want to create a compatible PFS slave for the target or not.
1037 .\" ==== mirror-stream ====
1038 .\".It Cm mirror-stream Ar [[user@]host:]filesystem [[user@]host:]filesystem
1039 .It Cm mirror-stream \
1040 Oo Oo Ar user Ns Cm @ Oc Ns Ar host Ns Cm \&: Oc Ns Ar filesystem \
1041 Oo Oo Ar user Ns Cm @ Oc Ns Ar host Ns Cm \&: Oc Ns Ar filesystem
1042 This command works similarly to
1044 but does not exit after the initial mirroring completes.
1045 The mirroring operation will resume as changes continue to be made to the
1047 The command is commonly used with
1051 options to keep the mirroring target in sync with the source on a continuing
1054 If the pipe is broken the command will automatically retry after sleeping
1056 The time slept will be 15 seconds plus the time given in the
1060 This command also detects the initial-mirroring case and spends some
1061 time scanning the B-Tree to find good break points, allowing the initial
1062 bulk mirroring operation to be broken down into about 20 separate pieces.
1063 This means that the user can kill and restart the operation and it will
1064 not have to start from scratch once it has gotten past the first chunk.
1067 option may be used to disable this feature and perform an initial bulk
1069 .\" ==== version ====
1070 .It Cm version Ar filesystem
1071 This command returns the
1073 file system version for the specified
1075 as well as the range of versions supported in the kernel.
1078 option may be used to remove the summary at the end.
1079 .\" ==== version-upgrade ====
1080 .It Cm version-upgrade Ar filesystem Ar version Op Cm force
1081 This command upgrades the
1086 Once upgraded a file system may not be downgraded.
1087 If you wish to upgrade a file system to a version greater or equal to the
1088 work-in-progress version number you must specify the
1091 Use of WIP versions should be relegated to testing and may require wiping
1092 the file system as development progresses, even though the WIP version might
1096 This command operates on the entire
1098 file system and is not a per PFS operation.
1099 All PFS's will be affected.
1100 .Bl -tag -width indent
1103 default version, first
1108 New directory entry layout.
1109 This version is using a new directory hash key.
1112 New snapshot management, using file system meta-data for saving
1113 configuration file and snapshots (transaction ids etc.).
1114 Also default snapshots directory has changed.
1118 New undo/flush, giving faster sync.
1122 .Sh PSEUDO-FILESYSTEM (PFS) NOTES
1123 The root of a PFS is not hooked into the primary
1125 file system as a directory.
1128 creates a special softlink called
1130 (exactly 10 characters long) in the primary
1134 then modifies the contents of the softlink as read by
1136 and thus what you see with an
1138 command or if you were to
1141 If the PFS is a master the link reflects the current state of the PFS.
1142 If the PFS is a slave the link reflects the last completed snapshot, and the
1143 contents of the link will change when the next snapshot is completed, and
1148 utility employs numerous safeties to reduce user foot-shooting.
1151 directive requires that the target be configured as a slave and that the
1153 field of the mirroring source and target match.
1154 .Sh UPGRADE INSTRUCTIONS HAMMER V1 TO V2
1155 This upgrade changes the way directory entries are stored.
1156 It is possible to upgrade a V1 file system to V2 in place, but
1157 directories created prior to the upgrade will continue to use
1160 Note that the slave mirroring code in the target kernel had bugs in
1161 V1 which can create an incompatible root directory on the slave.
1164 master created after the upgrade with a
1166 slave created prior to the upgrade.
1168 Any directories created after upgrading will use a new layout.
1169 .Sh UPGRADE INSTRUCTIONS HAMMER V2 TO V3
1170 This upgrade adds meta-data elements to the B-Tree.
1171 It is possible to upgrade a V2 file system to V3 in place.
1172 After issuing the upgrade be sure to run a
1175 to perform post-upgrade tasks.
1177 After making this upgrade running a
1182 directory for each PFS mount into
1183 .Pa /var/hammer/<pfs> .
1186 root mount will migrate
1189 .Pa /var/hammer/root .
1190 Migration occurs only once and only if you have not specified
1191 a snapshots directory in the PFS configuration.
1192 If you have specified a snapshots directory in the PFS configuration no
1193 automatic migration will occur.
1195 For slaves, if you desire, you can migrate your snapshots
1196 config to the new location manually and then clear the
1197 snapshot directory configuration in the slave PFS.
1198 The new snapshots hierarchy is designed to work with
1199 both master and slave PFSs equally well.
1201 In addition, the old config file will be moved to file system meta-data,
1202 editable via the new
1206 The old config file will be deleted.
1207 Migration occurs only once.
1209 The V3 file system has new
1211 directives for creating snapshots.
1212 All snapshot directives, including the original, will create
1213 meta-data entries for the snapshots and the pruning code will
1214 automatically incorporate these entries into its list and
1215 expire them the same way it expires softlinks.
1216 If you by accident blow away your snapshot softlinks you can use the
1218 directive to get a definitive list from the file system meta-data and
1219 regenerate them from that list.
1224 to backup file systems your scripts may be using the
1226 directive to generate transaction ids.
1227 This directive does not create a snapshot.
1228 You will have to modify your scripts to use the
1230 directive to generate the linkbuf for the softlink you create, or
1231 use one of the other
1236 directive will continue to work as expected and in V3 it will also
1237 record the snapshot transaction id in file system meta-data.
1238 You may also want to make use of the new
1240 tag for the meta-data.
1243 If you used to remove snapshot softlinks with
1245 you should probably start using the
1247 directive instead to also remove the related meta-data.
1248 The pruning code scans the meta-data so just removing the
1249 softlink is not sufficient.
1250 .Sh UPGRADE INSTRUCTIONS HAMMER V3 TO V4
1251 This upgrade changes undo/flush, giving faster sync.
1252 It is possible to upgrade a V3 file system to V4 in place.
1253 This upgrade reformats the UNDO FIFO (typically 1GB), so upgrade might take
1254 a minute or two depending.
1256 Version 4 allows the UNDO FIFO to be flushed without also having
1257 to flush the volume header, removing 2 of the 4 disk syncs typically
1258 required for an fsync() and removing 1 of the 2 disk syncs typically
1259 required for a flush sequence.
1263 .Bl -tag -width ".It Pa <fs>/var/slaves/<name>" -compact
1264 .It Pa <pfs>/snapshots
1265 default per PFS snapshots directory
1268 .It Pa /var/hammer/<pfs>
1269 default per PFS snapshots directory (not root)
1272 .It Pa /var/hammer/root
1273 default snapshots directory for root directory
1276 .It Pa <snapshots>/config
1283 .It Pa <fs>/var/slaves/<name>
1284 recommended slave PFS snapshots directory
1292 .Xr periodic.conf 5 ,
1293 .Xr mount_hammer 8 ,
1299 utility first appeared in
1302 .An Matthew Dillon Aq dillon@backplane.com
projects / dragonfly.git / blob