ig4 - Stop I2C controller after checking that it's kind of functional.
[dragonfly.git] / sbin / hammer2 / hammer2.8
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1.\" Copyright (c) 2015 The DragonFly Project. All rights reserved.
2.\"
3.\" This code is derived from software contributed to The DragonFly Project
4.\" by Matthew Dillon <dillon@backplane.com>
5.\"
6.\" Redistribution and use in source and binary forms, with or without
7.\" modification, are permitted provided that the following conditions
8.\" are met:
9.\"
10.\" 1. Redistributions of source code must retain the above copyright
11.\" notice, this list of conditions and the following disclaimer.
12.\" 2. Redistributions in binary form must reproduce the above copyright
13.\" notice, this list of conditions and the following disclaimer in
14.\" the documentation and/or other materials provided with the
15.\" distribution.
16.\" 3. Neither the name of The DragonFly Project nor the names of its
17.\" contributors may be used to endorse or promote products derived
18.\" from this software without specific, prior written permission.
19.\"
20.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
21.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
22.\" LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
23.\" FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
24.\" COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
25.\" INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
26.\" BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
27.\" LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
28.\" AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
29.\" OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
30.\" OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31.\" SUCH DAMAGE.
32.\"
4aedc17b 33.Dd December 2, 2017
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34.Dt HAMMER2 8
35.Os
36.Sh NAME
37.Nm hammer2
38.Nd hammer2 file system utility
39.Sh SYNOPSIS
40.Nm
41.Fl h
42.Nm
43.Op Fl s Ar path
44.Op Fl t Ar type
45.Op Fl u Ar uuid
944ddad0 46.Op Fl m Ar mem
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47.Ar command
48.Op Ar argument ...
49.Sh DESCRIPTION
50The
51.Nm
52utility provides miscellaneous support functions for a
53HAMMER2 file system.
54.Pp
55The options are as follows:
56.Bl -tag -width indent
57.It Fl s Ar path
58Specify the path to a mounted HAMMER2 filesystem.
59At least one PFS on a HAMMER2 filesystem must be mounted for the system
60to act on all PFSs managed by it.
61Every HAMMER2 filesystem typically has a PFS called "LOCAL" for this purpose.
62.It Fl t Ar type
63Specify the type when creating, upgrading, or downgrading a PFS.
8db69c9f 64Supported types are MASTER, SLAVE, SOFT_MASTER, SOFT_SLAVE, CACHE, and DUMMY.
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65If not specified the pfs-create directive will default to MASTER if no
66uuid is specified, and SLAVE if a uuid is specified.
67.It Fl u Ar uuid
68Specify the cluster uuid when creating a PFS. If not specified, a unique,
69random uuid will be generated.
70Note that every PFS also has a unique pfs_id which is always generated
71and cannot be overridden with an option.
72The { pfs_clid, pfs_fsid } tuple uniquely identifies a component of a cluster.
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73.It Fl m Ar mem
74Specify how much tracking memory to use for certain directives.
75At the moment, this option is only applicable to the
76.Cm bulkfree
77directive, allowing it to operate in fewer passes when given more memory.
78A nominal value for a 4TB drive with a ton of stuff on it would be around
79a gigabyte '-m 1g'.
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80.El
81.Pp
82.Nm
83directives are as shown below.
84Note that most directives require you to either be CD'd into a hammer2
85filesystem, specify a path to a mounted hammer2 filesystem via the
86.Fl s
87option, or specify a path after the directive.
88It depends on the directive.
89All hammer2 filesystem have a PFS called "LOCAL" which is typically mounted
90locally on the host in order to be able to issue commands for other PFSs
91on the filesystem.
92The mount also enables PFS configuration scanning for that filesystem.
93.Bl -tag -width indent
4aedc17b 94.\" ==== cleanup ====
95.It Cm cleanup Op path
96Perform manual cleanup passes on paths or all mounted partitions.
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97.\" ==== connect ====
98.It Cm connect Ar target
99Add a cluster link entry to the volume header.
100The volume header can support up to 255 link entries.
101This feature is not currently used.
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102.\" ==== destroy ====
103.It Cm destroy Ar path
104Destroy the specified directory entry in a hammer2 filesystem. This bypasses
105all normal checks and will unconditionally destroy the directory entry.
106The underlying inode is not checked and, if it does exist, its nlinks count
107is not decremented.
108This directive should only be used to destroy a corrupted directory entry
109which no longer has a working inode.
110.Pp
111Note that this command may desynchronize the system namecache for the
112specified entry. If this happens, you may have to unmount and remount the
113filesystem.
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114.\" ==== disconnect ====
115.It Cm disconnect Ar target
116Delete a cluster link entry from the volume header.
117This feature is not currently used.
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118.\" ==== info ====
119.It Cm info Op devpath
120Access and print the status and super-root entries for all HAMMER2
121partitions found in /dev/serno or the specified device path(s).
122The partitions do not have to be mounted.
123Note that only mounted partitions will be under active management.
124This is accomplished by mounting at least one PFS within the partition.
125Typically at least the @LOCAL PFS is mounted.
126.\" ==== mountall ====
127.It Cm mountall Op devpath
128This directive mounts the @LOCAL PFS on all HAMMER2 partitions found
129in /dev/serno, or the specified device path(s).
130The partitions are mounted as /var/hammer2/LOCAL.<id>.
131Mounts are executed in the background and this command will wait a
132limited amount of time for the mounts to complete before returning.
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133.\" ==== status ====
134.It Cm status Ar path...
135Dump a list of all cluster link entries configured in the volume header.
136.\" ==== hash ====
137.It Cm hash Ar filename...
138Compute and print the directory hash for any number of filenames.
139.\" ==== pfs-list ====
140.It Cm pfs-list Op path...
141List all local PFSs available on a mounted HAMMER2 filesystem, their type,
142and their current status.
143You must mount at least one PFS in order to be able to access the whole list.
144.\" ==== pfs-clid ====
145.It Cm pfs-clid Ar label
146Print the cluster id for a PFS specified by name.
147.\" ==== pfs-fsid ====
148.It Cm pfs-fsid Ar label
149Print the unique filesystem id for a PFS specified by name.
150.\" ==== pfs-create ====
151.It Cm pfs-create Ar label
152Create a local PFS on a mounted HAMMER2 filesystem.
153If no uuid is specified the pfs-type defaults to MASTER.
154If a uuid is specified via the
155.Fl u
156option the pfs-type defaults to SLAVE.
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157Other types can be specified with the
158.Fl t
159option.
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160.Pp
161If you wish to add a MASTER to an existing cluster, you must first add it as
162a SLAVE and then upgrade it to MASTER to properly synchronize it.
163.Pp
164The DUMMY pfs-type is used to tie network-accessible clusters into the local
165machine when no local storage is desired.
166This type should be used on minimal H2 partitions or entirely in ram for
167netboot-centric systems to provide a tie-in point for the mount command,
168or on more complex systems where you need to also access network-centric
169clusters.
170.Pp
171The CACHE or SLAVE pfs-type is typically used when the main store is on
172the network but local storage is desired to improve performance.
173SLAVE is also used when a backup is desired.
174.Pp
175Generally speaking, you can mount any PFS element of a cluster in order to
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176access the cluster via the full cluster protocol.
177There are two exceptions.
178If you mount a SOFT_SLAVE or a SOFT_MASTER then soft quorum semantics are
179employed... the soft slave or soft master's current state will always be used
180and the quorum protocol will not be used. The soft PFS will still be
4b47781a 181synchronized to masters in the background when available.
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182Also, you can use
183.Sq mount -o local
184to mount ONLY a local HAMMER2 PFS and
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185not run any network or quorum protocols for the mount.
186All such mounts except for a SOFT_MASTER mount will be read-only.
187Other than that, you will be mounting the whole cluster when you mount any
188PFS within the cluster.
189.Pp
190DUMMY - Create a PFS skeleton intended to be the mount point for a
191more complex cluster, probably one that is entirely network based.
192No data will be synchronized to this PFS so it is suitable for use
193in a network boot image or memory filesystem.
194This allows you to create placeholders for mount points on your local
195disk, SSD, or memory disk.
196.Pp
197CACHE - Create a PFS for caching portions of the cluster piecemeal.
198This is similar to a SLAVE but does not synchronize the entire contents of
199the cluster to the PFS.
200Elements found in the CACHE PFS which are validated against the cluster
201will be read, presumably a faster access than having to go to the cluster.
202Only local CACHEs will be updated.
7c5aac38 203Network-accessible CACHE PFSs might be read but will not be written to.
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204If you have a large hard-drive-based cluster you can set up localized
205SSD CACHE PFSs to improve performance.
206.Pp
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207SLAVE - Create a PFS which maintains synchronization with and provides a
208read-only copy of the cluster.
209HAMMER2 will prioritize local SLAVEs for data retrieval after validating
210their transaction id against the cluster.
211The difference between a CACHE and a SLAVE is that the SLAVE is synchronized
212to a full copy of the cluster and thus can serve as a backup or be staged
213for use as a MASTER later on.
214.Pp
215SOFT_SLAVE - Create a PFS which maintains synchronization with and provides
216a read-only copy of the cluster.
217This is one of the special mount cases. A SOFT_SLAVE will synchronize with
218the cluster when the cluster is available, but can still be accessed when
219the cluster is not available.
220.Pp
221MASTER - Create a PFS which will hold a master copy of the cluster.
222If you create several MASTER PFSs with the same cluster id you are
223effectively creating a multi-master cluster and causing a quorum and
224cache coherency protocol to be used to validate operations.
225The total number of masters is stored in each PFSs making up the cluster.
226Filesystem operations will stall for normal mounts if a quorum cannot be
227obtained to validate the operation.
228MASTER nodes which go offline and return later will synchronize in the
229background.
230Note that when adding a MASTER to an existing cluster you must add the
231new PFS as a SLAVE and then upgrade it to a MASTER.
232.Pp
233SOFT_MASTER - Create a PFS which maintains synchronization with and provides
234a read-write copy of the cluster.
235This is one of the special mount cases. A SOFT_MASTER will synchronize with
236the cluster when the cluster is available, but can still be read AND written
237to even when the cluster is not available.
238Modifications made to a SOFT_MASTER will be automatically flushed to the
239cluster when it becomes accessible again, and vise-versa.
240Manual intervention may be required if a conflict occurs during
241synchronization.
242.\" ==== pfs-delete ====
243.It Cm pfs-delete Ar label
244Delete a local PFS on a mounted HAMMER2 filesystem.
245Deleting a PFS of type MASTER requires first downgrading it to a SLAVE (XXX).
246.\" ==== snapshot ====
247.It Cm snapshot Ar path Op label
248Create a snapshot of a directory.
249This can only be used on a local PFS, and is only really useful if the PFS
250contains a complete copy of what you desire to snapshot so that typically
251means a local MASTER, SOFT_MASTER, SLAVE, or SOFT_SLAVE must be present.
252Snapshots are created simply by flushing a PFS mount to disk and then copying
253the directory inode to the PFS.
254The topology is snapshotted without having to be copied or scanned.
255Snapshots are effectively separate from the cluster they came from
256and can be used as a starting point for a new cluster.
257So unless you build a new cluster from the snapshot, it will stay local
258to the machine it was made on.
259.\" ==== service ====
260.It Cm service
261Start the
262.Nm
263service daemon.
264This daemon is also automatically started when you run
265.Xr mount_hammer2 8 .
266The hammer2 service daemon handles incoming TCP connections and maintains
267outgoing TCP connections. It will interconnect available services on the
268machine (e.g. hammer2 mounts and xdisks) to the network.
269.\" ==== stat ====
270.It Cm stat Op path...
271Print the inode statistics, compression, and other meta-data associated
272with a list of paths.
273.\" ==== leaf ====
274.It Cm leaf
275XXX
276.\" ==== shell ====
277.It Cm shell
278Start a debug shell to the local hammer2 service daemon via the DMSG protocol.
279.\" ==== debugspan ====
280.It Cm debugspan
281(do not use)
282.\" ==== rsainit ====
283.It Cm rsainit
284Create the
285.Pa /etc/hammer2
286directory and initialize a public/private keypair in that directory for
287use by the network cluster protocols.
288.\" ==== show ====
289.It Cm show Ar devpath
290Dump the radix tree for the HAMMER2 filesystem by scanning a
291block device directly. No mount is required.
292.\" ==== freemap ====
293Dump the freemap tree for the HAMMER2 filesystem by scanning a
294block device directly. No mount is required.
295.It Cm freemap Ar devpath
296.\" ==== setcomp ====
297.It Cm setcomp Ar mode[:level] Op path...
298Set the compression mode as specified for any newly created elements at or
299under the path if not overridden by deeper elements.
300Available modes are none, autozero, lz4, or zlib.
301When zlib is used the compression level can be set.
302The default will be 6 which is the best trade-off between performance and
303time.
304.Pp
305newfs_hammer2 will set the default compression to lz4 which prioritizes
306speed over performance.
307Also note that HAMMER2 contains a heuristic and will not attempt to
308compress every block if it detects a sufficient amount of uncompressable
309data.
310.Pp
311Hammer2 compression is only effective when it can reduce the size of dataset
312(typically a 64KB block) by one or more powers of 2. A 64K block which
313only compresses to 40K will not yield any storage improvement.
3d4f397a 314.Pp
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315Generally speaking you do not want to set the compression mode to
316.Sq none ,
3d4f397a 317as this will cause blocks of all-zeros to be written as all-zero blocks,
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318instead of holes. The
319.Sq autozero
320compression mode detects blocks of all-zeros
3d4f397a 321and writes them as holes. However, HAMMER2 will rewrite data in-place if
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322the compression mode is set to
323.Sq none
324and the check code is set to
325.Sq disabled .
326Formal snapshots will still snapshot such files. However,
3d4f397a 327de-duplication will no longer function on the data blocks.
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328.\" ==== setcheck ====
329.It Cm setcheck Ar check Op path...
330Set the check code as specified for any newly created elements at or under
331the path if not overridden by deeper elements.
b83c55fc 332Available codes are default, disabled, crc32, xxhash64, or sha192.
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333.\" ==== clrcheck ====
334.It Cm clrcheck Op path...
335Clear the check code override for the specified paths.
336Overrides may still be present in deeper elements.
337.\" ==== setcrc32 ====
338.It Cm setcrc32 Op path...
339Set the check code to the ISCSI 32-bit CRC for any newly created elements
340at or under the path if not overridden by deeper elements.
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341.\" ==== setxxhash64 ====
342.It Cm setxxhash64 Op path...
343Set the check code to XXHASH64, a fast 64-bit hash
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344.\" ==== setsha192 ====
345.It Cm setsha192 Op path...
346Set the check code to SHA192 for any newly created elements at or under
347the path if not overridden by deeper elements.
348.\" ==== bulkfree ====
349.It Cm bulkfree Op path...
350Run a bulkfree pass on a HAMMER2 mount.
351You can specify any PFS for the mount, the bulkfree pass is run on the
352entire partition.
b83c55fc 353Note that it takes two passes to actually free space.
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354By default this directive will use up to 1/16 physical memory to track
355the freemap. The amount of memory used may be overridden with the
356.Op Fl m Ar mem
357option.
3c198419 358.El
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359.Sh SYSCTLS
360.Bl -tag -width indent
361.It Va vfs.hammer2.dedup_enable (default on)
362Enables live de-duplication. Any recently read data that is on-media
363(already synchronized to media) is tested against pending writes for
364compatibility. If a match is found, the write will reference the
365existing on-media data instead of writing new data.
366.It Va vfs.hammer2.always_compress (default off)
367This disables the H2 compression heuristic and forces H2 to always
368try to compress data blocks, even if they look uncompressable.
369Enabling this option reduces performance but has higher de-duplication
370repeatability.
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371.It Va vfs.hammer2.cluster_data_read (default 4)
372.It Va vfs.hammer2.cluster_meta_read (default 1)
373Set the amount of read-ahead clustering to perform on data and meta-data
374blocks.
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375.It Va vfs.hammer2.cluster_write (default 4)
376Set the amount of write-behind clustering to perform in buffers. Each
377buffer represents 64KB. The default is 4 and higher values typically do
378not improve performance. A value of 0 disables clustered writes.
379This variable applies to the underlying media device, not to logical
380file writes, so it should not interfere with temporary file optimization.
381Generally speaking you want this enabled to generate smoothly pipelined
382writes to the media.
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383.It Va vfs.hammer2.bulkfree_tps (default 5000)
384Set bulkfree's maximum scan rate. This is primarily intended to limit
385I/O utilization on SSDs and cpu utilization when the meta-data is mostly
386cached in memory.
3d4f397a 387.El
3c198419 388.Sh SETTING UP /etc/hammer2
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389The
390.Sq rsainit
391directive will create the
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392.Pa /etc/hammer2
393directory with appropriate permissions and also generate a public key
394pair in this directory for the machine. These files will be
395.Pa rsa.pub
396and
397.Pa rsa.prv
398and needless to say, the private key shouldn't leave the host.
399.Pp
400The service daemon will also scan the
401.Pa /etc/hammer2/autoconn
402file which contains a list of hosts which it will automatically maintain
403connections to to form your cluster.
404The service daemon will automatically reconnect on any failure and will
405also monitor the file for changes.
406.Pp
407When the service daemon receives a connection it expects to find a
408public key for that connection in a file in
409.Pa /etc/hammer2/remote/
410called
411.Pa <IPADDR>.pub .
412You normally copy the
413.Pa rsa.pub
414key from the host in question to this file.
415The IP address must match exactly or the connection will not be allowed.
416.Pp
417If you want to use an unencrypted connection you can create empty,
418dummy files in the remote directory in the form
419.Pa <IPADDR>.none .
420We do not recommend using unencrypted connections.
421.Sh CLUSTER SERVICES
422Currently there are two services which use the cluster network infrastructure,
423HAMMER2 mounts and XDISK.
424Any HAMMER2 mount will make all PFSs for that filesystem available to the
425cluster.
426And if the XDISK kernel module is loaded, the hammer2 service daemon will make
427your machine's block devices available to the cluster (you must load the
428xdisk.ko kernel module before starting the hammer2 service).
429They will show up as
430.Pa /dev/xa*
431and
432.Pa /dev/serno/*
433devices on the remote machines making up the cluster.
434Remote block devices are just what they appear to be... direct access to a
435block device on a remote machine. If the link goes down remote accesses
436will stall until it comes back up again, then automatically requeue any
437pending I/O and resume as if nothing happened.
438However, if the server hosting the physical disks crashes or is rebooted,
439any remote opens to its devices will see a permanent I/O failure requiring a
440close and open sequence to re-establish.
441The latter is necessary because the server's drives might not have committed
442the data before the crash, but had already acknowledged the transfer.
443.Pp
444Data commits work exactly the same as they do for real block devices.
445The originater must issue a BUF_CMD_FLUSH.
446.Sh ADDING A NEW MASTER TO A CLUSTER
447When you
448.Xr newfs_hammer2 8
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449a HAMMER2 filesystem or use the
450.Sq pfs-create
451directive on one already mounted
3c198419 452to create a new PFS, with no special options, you wind up with a PFS
4b47781a 453typed as a MASTER and a unique cluster uuid, but because there is only one
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454PFS for that cluster (for each PFS you create via pfs-create), it will
455act just like a normal filesystem would act and does not require any special
456protocols to operate.
457.Pp
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458If you use the
459.Sq pfs-create
460directive along with the
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461.Fl u
462option to specify a cluster uuid that already exists in the cluster,
463you are adding a PFS to an existing cluster and this can trigger a whole
464series of events in the background.
465When you specify the
466.Fl u
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467option in a
468.Sq pfs-create ,
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469.Nm
470will by default create a SLAVE PFS.
471In fact, this is what must be created first even if you want to add a new
472MASTER to your cluster.
473.Pp
474The most common action a system admin will want to take is to upgrade or
475downgrade a PFS.
476A new MASTER can be added to the cluster by upgrading an existing SLAVE
477to MASTER.
478A MASTER can be removed from the cluster by downgrading it to a SLAVE.
479Upgrades and downgrades will put nodes in the cluster in a transition state
480until the operation is complete.
481For downgrades the transition state is fleeting unless one or more other
482masters has not acknowledged the change.
483For upgrades a background synchronization process must complete before the
484transition can be said to be complete, and the node remains (really) a SLAVE
485until that transition is complete.
486.Sh USE CASES FOR A SOFT_MASTER
487The SOFT_MASTER PFS type is a special type which must be specifically
488mounted by a machine.
489It is a R/W mount which does not use the quorum protocol and is not
490cache coherent with the cluster, but which synchronizes from the cluster
491and allows modifying operations which will synchronize to the cluster.
492The most common case is to use a SOFT_MASTER PFS in a laptop allowing you
493to work on your laptop when you are on the road and not connected to
494your main servers, and for the laptop to synchronize when a connection is
495available.
496.Sh USE CASES FOR A SOFT_SLAVE
497A SOFT_SLAVE PFS type is a special type which must be specifically mounted
498by a machine.
499It is a RO mount which does not use the quorum protocol and is not
500cache coherent with the cluster. It will receive synchronization from
501the cluster when network connectivity is available but will not stall if
502network connectivity is lost.
503.Sh FSYNC FLUSH MODES
504TODO.
505.Sh RESTORING FROM A SNAPSHOT BACKUP
506TODO.
125966e8 507.Sh PERFORMANCE TUNING
2af25173 508Because HAMMER2 implements compression, decompression, and dedup natively,
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509it always double-buffers file data. This means that the file data is
510cached via the device vnode (in compressed / dedupped-form) and the same
511data is also cached by the file vnode (in decompressed / non-dedupped form).
512.Pp
513While HAMMER2 will try to age the logical file buffers on its, some
514additional performance tuning may be necessary for optimal operation
515whether swapcache is used or not. Our recommendation is to reduce the
516number of vnodes (and thus also the logical buffer cache behind the
517vnodes) that the system caches via the
518.Va kern.maxvnodes
519sysctl.
520.Pp
521Too-large a value will result in excessive double-caching and can cause
522unnecessary read disk I/O.
523We recommend a number between 25000 and 250000 vnodes, depending on your
524use case.
525Keep in mind that even though the vnode cache is smaller, this will make
526room for a great deal more device-level buffer caching which can encompasses
527far more data and meta-data than the vnode-level caching.
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528.Sh ENVIRONMENT
529TODO.
530.Sh FILES
531.Bl -tag -width ".It Pa <fs>/abc/defghi/<name>" -compact
532.It Pa /etc/hammer2/
533.It Pa /etc/hammer2/rsa.pub
534.It Pa /etc/hammer2/rsa.prv
535.It Pa /etc/hammer2/autoconn
536.It Pa /etc/hammer2/remote/<IP>.pub
537.It Pa /etc/hammer2/remote/<IP>.none
538.El
539.Sh EXIT STATUS
540.Ex -std
541.Sh SEE ALSO
542.Xr mount_hammer2 8 ,
543.Xr mount_null 8 ,
544.Xr newfs_hammer2 8 ,
545.Xr swapcache 8 ,
546.Xr sysctl 8
547.Sh HISTORY
548The
549.Nm
550utility first appeared in
551.Dx 4.1 .
552.Sh AUTHORS
553.An Matthew Dillon Aq Mt dillon@backplane.com