1SSM(8)                      System Storage Manager                      SSM(8)
2
3
4

NAME

6       ssm - System Storage Manager: a single tool to manage your storage
7

SYNOPSIS

9       ssm  [-h]  [--version]  [-v]  [-v**v]  [-v**vv]  [-f] [-b BACKEND] [-n]
10       {check,resize,create,list,info,add,remove,snapshot,mount,migrate} ...
11
12       ssm create [-h] [-s SIZE] [-n NAME] [--fstype FSTYPE]  [-r  LEVEL]  [-I
13       STRIPESIZE] [-i STRIPES] [-p POOL] [-e [{luks,plain}]] [-o MNT_OPTIONS]
14       [-v VIRTUAL_SIZE] [device ...] [mount]
15
16       ssm    list    [-h]    [{volumes,vol,dev,devices,pool,pools,fs,filesys‐
17       tems,snap,snapshots}]
18
19       ssm info [-h] [item]
20
21       ssm remove [-h] [-a] [items ...]
22
23       ssm resize [-h] [-s SIZE] volume [device ...]
24
25       ssm check [-h] device [device ...]
26
27       ssm snapshot [-h] [-s SIZE] [-d DEST | -n NAME] volume
28
29       ssm add [-h] [-p POOL] device [device ...]
30
31       ssm mount [-h] [-o OPTIONS] volume directory
32
33       ssm migrate [-h] source target
34

DESCRIPTION

36       System  Storage  Manager provides an easy to use command line interface
37       to manage your storage using various technologies like lvm, btrfs,  en‐
38       crypted volumes and more.
39
40       In  more sophisticated enterprise storage environments, management with
41       Device Mapper (dm), Logical Volume Manager (LVM), or  Multiple  Devices
42       (md)  is becoming increasingly more difficult.  With file systems added
43       to the mix, the number of tools needed to configure and manage  storage
44       has  grown  so large that it is simply not user friendly.  With so many
45       options for a system administrator to consider, the opportunity for er‐
46       rors and problems is large.
47
48       The  btrfs  administration  tools have shown us that storage management
49       can be simplified, and we are working to bring  that  ease  of  use  to
50       Linux filesystems in general.
51

OPTIONS

SYSTEM STORAGE MANAGER COMMANDS

54   Introduction
55       System Storage Manager has several commands that you can specify on the
56       command line as a first argument to ssm. They all have a  specific  use
57       and their own arguments, but global ssm arguments are propagated to all
58       commands.
59
60   Create command
61       ssm create [-h] [-s SIZE] [-n NAME] [--fstype FSTYPE]  [-r  LEVEL]  [-I
62       STRIPESIZE] [-i STRIPES] [-p POOL] [-e [{luks,plain}]] [-o MNT_OPTIONS]
63       [-v VIRTUAL_SIZE] [device ...] [mount]
64
65       This command creates a new volume with defined parameters. If a  device
66       is  provided  it  will  be  used to create the volume, hence it will be
67       added into the pool prior to volume creation (See Add command section).
68       More than one device can be used to create a volume.
69
70       If  the device is already being used in a different pool, then ssm will
71       ask you whether you want to remove it from the original  pool.  If  you
72       decline,  or  the  removal fails, then the volume creation fails if the
73       SIZE was not provided. On the other hand, if the SIZE is  provided  and
74       some  devices  can  not be added to the pool, the volume creation might
75       still succeed if there is enough space in the pool.
76
77       In addition to specifying size of the volume directly,  percentage  can
78       be specified as well. Specify --size 70% to indicate the volume size to
79       be 70% of total pool size. Additionally, percentage  of  the  used,  or
80       free  pool  space can be specified as well using keywords FREE, or USED
81       respectively.
82
83       The POOL name can be specified as well. If the pool exists, a new  vol‐
84       ume  will  be created from that pool (optionally adding device into the
85       pool).  However if the POOL does not exist, then ssm  will  attempt  to
86       create  a new pool with the provided device, and then create a new vol‐
87       ume from this pool. If the --backend argument is omitted,  the  default
88       ssm backend will be used. The default backend is lvm.
89
90       ssm also supports creating a RAID configuration, however some back-ends
91       might not support all RAID levels, or may not even support RAID at all.
92       In this case, volume creation will fail.
93
94       If  a mount point is provided, ssm will attempt to mount the volume af‐
95       ter it is created. However it will fail if mountable file system is not
96       present on the volume.
97
98       If  the  backend allows it (currently only supported with lvm backend),
99       ssm can be used to create  thinly  provisioned  volumes  by  specifying
100       --virtual-size  option. This will automatically create a thin pool of a
101       given size provided with --size option and thin volume of a given  size
102       provided  with  --virtual-size option and name provided with --name op‐
103       tion. Virtual size can be much bigger than available space in the pool.
104
105   Info command
106       ssm info [-h] [item]
107
108       EXPERIMENTAL This feature is currently experimental. The output  format
109       can change and fields can be added or removed.
110
111       Show  detailed  information  about all detected devices, pools, volumes
112       and snapshots found on the system. The info command can be used  either
113       alone  to  show all available items, or you can specify a device, pool,
114       or any other identifier to see information about the specific item.
115
116   List command
117       ssm    list    [-h]    [{volumes,vol,dev,devices,pool,pools,fs,filesys‐
118       tems,snap,snapshots}]
119
120       Lists  information about all detected devices, pools, volumes and snap‐
121       shots found on the system. The list command can be used either alone to
122       list all of the information, or you can request specific sections only.
123
124       The following sections can be specified:
125
126       {volumes | vol}
127              List information about all volumes found in the system.
128
129       {devices | dev}
130              List information about all devices found on the system. Some de‐
131              vices are intentionally hidden, like for example cdrom or  DM/MD
132              devices since those are actually listed as volumes.
133
134       {pools | pool}
135              List information about all pools found in the system.
136
137       {filesystems | fs}
138              List  information about all volumes containing filesystems found
139              in the system.
140
141       {snapshots | snap}
142              List information about all snapshots found in the  system.  Note
143              that  some back-ends do not support snapshotting and some cannot
144              distinguish snapshot from regular volumes.  In  this  case,  ssm
145              will  try  to  recognize  the volume name in order to identify a
146              snapshot, but if the ssm regular expression does not  match  the
147              snapshot  pattern,  the  problematic snapshot will not be recog‐
148              nized.
149
150   Remove command
151       ssm remove [-h] [-a] [items ...]
152
153       This command removes an item from the system.  Multiple  items  can  be
154       specified.   If  the item cannot be removed for some reason, it will be
155       skipped.
156
157       An item can be any of the following:
158
159       device Remove a device from the pool. Note that this cannot be done  in
160              some  cases  where the device is being used by the pool. You can
161              use the -f argument to force removal. If the device does not be‐
162              long to any pool, it will be skipped.
163
164       pool   Remove a pool from the system. This will also remove all volumes
165              created from that pool.
166
167       volume Remove a volume from the system. Note that this will fail if the
168              volume is mounted and cannot be forced with -f.
169
170   Resize command
171       ssm resize [-h] [-s SIZE] volume [device ...]
172
173       Change  size of the volume and file system. If there is no file system,
174       only the volume itself will be resized. You can specify a device to add
175       into  the  volume pool prior the resize. Note that the device will only
176       be added into the pool if the volume size is going to grow.
177
178       If the device is already used in a different pool, then  ssm  will  ask
179       you whether or not you want to remove it from the original pool.
180
181       In  some  cases,  the file system has to be mounted in order to resize.
182       This will be handled by ssm automatically by mounting the volume tempo‐
183       rarily.
184
185       In  addition  to specifying new size of the volume directly, percentage
186       can be specified as well. Specify --size 70% to resize  the  volume  to
187       70%  of  it's  original  size. Additionally, percentage of the used, or
188       free pool space can be specified as well using keywords FREE,  or  USED
189       respectively.
190
191       Note  that  resizing  btrfs  subvolume is not supported, only the whole
192       file system can be resized.
193
194   Check command
195       ssm check [-h] device [device ...]
196
197       Check the file system consistency on the volume. You can specify multi‐
198       ple  volumes  to  check. If there is no file system on the volume, this
199       volume will be skipped.
200
201       In some cases the file system has to be mounted in order to  check  the
202       file system.  This will be handled by ssm automatically by mounting the
203       volume temporarily.
204
205   Snapshot command
206       ssm snapshot [-h] [-s SIZE] [-d DEST | -n NAME] volume
207
208       Take a snapshot of an existing volume. This operation will fail if  the
209       back-end  to which the volume belongs to does not support snapshotting.
210       Note that you cannot specify both NAME and DEST since those options are
211       mutually exclusive.
212
213       In  addition  to specifying new size of the volume directly, percentage
214       can be specified as well. Specify --size 70% to indicate the new  snap‐
215       shot size to be 70% of the origin volume size. Additionally, percentage
216       of the used, or free pool space can be specified as well using keywords
217       FREE, or USED respectively.
218
219       In  some  cases  the  file  system has to be mounted in order to take a
220       snapshot of the volume. This will be handled by  ssm  automatically  by
221       mounting the volume temporarily.
222
223   Add command
224       ssm add [-h] [-p POOL] device [device ...]
225
226       This  command  adds a device into the pool. By default, the device will
227       not be added if it's already a part of a different pool, but  the  user
228       will  be  asked whether or not to remove the device from its pool. When
229       multiple devices are provided, all of them are added into the pool.  If
230       one  of  the  devices cannot be added into the pool for any reason, the
231       add command will fail. If no pool is specified, the default  pool  will
232       be chosen. In the case of a non existing pool, it will be created using
233       the provided devices.
234
235   Mount command
236       ssm mount [-h] [-o OPTIONS] volume directory
237
238       This command will mount the volume at the specified directory. The vol‐
239       ume can be specified in the same way as with mount(8), however in addi‐
240       tion, one can also specify a volume in the format as it appears in  the
241       ssm list table.
242
243       For example, instead of finding out what the device and subvolume id of
244       the btrfs subvolume "btrfs_pool:vol001" is in order to  mount  it,  one
245       can simply call ssm mount btrfs_pool:vol001 /mnt/test.
246
247       One can also specify OPTIONS in the same way as with mount(8).
248
249   Migrate command
250       ssm migrate [-h] source target
251
252       Move  data from one device to another. For btrfs and lvm their special‐
253       ized utilities are used, so the data are  moved  in  an  all-or-nothing
254       fashion  and  no other operation is needed to add/remove the devices or
255       rebalance the pool.  Devices that do not belong to a backend that  sup‐
256       ports specialized device migration tools will be migrated using dd.
257
258       This  operation is not intended to be used for duplication, because the
259       process can change metadata and an access to the data may be difficult.
260

BACK-ENDS

262   Introduction
263       Ssm aims to create a unified user interface  for  various  technologies
264       like  Device  Mapper (dm), Btrfs file system, Multiple Devices (md) and
265       possibly more. In order to do so we have a core  abstraction  layer  in
266       ssmlib/main.py.  This  abstraction  layer  should  ideally know nothing
267       about the underlying technology, but rather comply  with  device,  pool
268       and volume abstractions.
269
270       Various backends can be registered in ssmlib/main.py in order to handle
271       specific storage technology, implementing methods  like  create,  snap‐
272       shot,  or remove volumes and pools. The core will then call these meth‐
273       ods to manage the storage without needing to know what lies  underneath
274       it. There are already several backends registered in ssm.
275
276   Btrfs backend
277       Btrfs  is  the file system with many advanced features including volume
278       management. This is the reason why btrfs is  handled  differently  than
279       other  conventional file systems in ssm. It is used as a volume manage‐
280       ment back-end.
281
282       Pools, volumes and snapshots can be created with btrfs backend and here
283       is what it means from the btrfs point of view:
284
285       pool   A pool is actually a btrfs file system itself, because it can be
286              extended by adding more devices, or shrunk by  removing  devices
287              from  it. Subvolumes and snapshots can also be created. When the
288              new btrfs pool should be created, ssm  simply  creates  a  btrfs
289              file  system, which means that every new btrfs pool has one vol‐
290              ume of the same name as the pool itself which can not be removed
291              without removing the entire pool. The default btrfs pool name is
292              btrfs_pool.
293
294              When creating a new btrfs pool, the name of the pool is used  as
295              the  file  system  label.  If there is an already existing btrfs
296              file system in the system without a label,  a  btrfs  pool  name
297              will  be  generated  for  internal  use  in the following format
298              "btrfs_{device base name}".
299
300              A btrfs pool is created when the create or add command  is  used
301              with specified devices and non existing pool name.
302
303       volume A  volume in the btrfs back-end is actually just btrfs subvolume
304              with the exception of the first volume  created  on  btrfs  pool
305              creation,  which  is the file system itself. Subvolumes can only
306              be created on the btrfs file system when it is mounted, but  the
307              user  does not have to worry about that since ssm will automati‐
308              cally mount the file system temporarily in order to create a new
309              subvolume.
310
311              The volume name is used as subvolume path in the btrfs file sys‐
312              tem and every object in this path must exist in order to  create
313              a volume. The volume name for internal tracking and that is vis‐
314              ible to the user is generated in the format "{pool_name}:{volume
315              name}", but volumes can be also referenced by its mount point.
316
317              The  btrfs  volumes  are only shown in the list output, when the
318              file system is mounted, with the exception  of  the  main  btrfs
319              volume - the file system itself.
320
321              Also  note  that btrfs volumes and subvolumes cannot be resized.
322              This is mainly limitation of the btrfs tools which currently  do
323              not work reliably.
324
325              A new btrfs volume can be created with the create command.
326
327       snapshot
328              The  btrfs  file  system supports subvolume snapshotting, so you
329              can take a snapshot of any btrfs volume in the system with  ssm.
330              However  btrfs does not distinguish between subvolumes and snap‐
331              shots, because a snapshot is actually just a subvolume with some
332              blocks  shared with a different subvolume.  This means, that ssm
333              is not able to directly recognize a  btrfs  snapshot.   Instead,
334              ssm  will  try  to  recognize a special name format of the btrfs
335              volume that denotes it is a snapshot. However, if  the  NAME  is
336              specified  when  creating snapshot which does not match the spe‐
337              cial pattern, snapshot will not be recognized by the ssm and  it
338              will be listed as regular btrfs volume.
339
340              A new btrfs snapshot can be created with the snapshot command.
341
342       device Btrfs does not require a special device to be created on.
343
344   Lvm backend
345       Pools, volumes and snapshots can be created with lvm, which pretty much
346       match the lvm abstraction.
347
348       pool   An lvm pool is just a volume group in  lvm  language.  It  means
349              that  it is grouping devices and new logical volumes can be cre‐
350              ated out of  the  lvm  pool.   The  default  lvm  pool  name  is
351              lvm_pool.
352
353              An  lvm pool is created when the create or add commands are used
354              with specified devices and a non existing pool name.
355
356              Alternatively a thin pool can be created as a  result  of  using
357              --virtual-size option to create thin volume.
358
359       volume An  lvm  volume is just a logical volume in lvm language. An lvm
360              volume can be created with the create command.
361
362       snapshot
363              Lvm volumes can be snapshotted as well. When a snapshot is  cre‐
364              ated  from  the  lvm  volume,  a new snapshot volume is created,
365              which can be handled as any other lvm volume. Unlike  btrfs  lvm
366              is able to distinguish snapshot from regular volume, so there is
367              no need for a snapshot name to match special pattern.
368
369       device Lvm requires a physical device to be created on the device,  but
370              with ssm this is transparent for the user.
371
372   Crypt backend
373       The  crypt backend in ssm uses cryptsetup and dm-crypt target to manage
374       encrypted volumes. The crypt backend can be used as a  regular  backend
375       for creating encrypted volumes on top of regular block devices, or even
376       other volumes (lvm or md volumes for example). Or it  can  be  used  to
377       create encrypted lvm volumes right away in a single step.
378
379       Only  volumes  can be created with crypt backend. This backend does not
380       support pooling and does not require special devices.
381
382       pool   The crypt backend does not support pooling, and it is not possi‐
383              ble to create crypt pool or add a device into a pool.
384
385       volume A  volume in the crypt backend is the volume created by dm-crypt
386              which represents the data on the original  encrypted  device  in
387              unencrypted  form.   The crypt backend does not support pooling,
388              so only one device can be used to create crypt volume.  It  also
389              does not support raid or any device concatenation.
390
391              Currently  two  modes,  or  extensions  are  supported: luks and
392              plain. Luks is used by default. For more information  about  the
393              extensions, please see cryptsetup manual page.
394
395       snapshot
396              The  crypt backend does not support snapshotting, however if the
397              encrypted volume is created on top of an  lvm  volume,  the  lvm
398              volume  itself  can  be  snapshotted.  The  snapshot can be then
399              opened by using cryptsetup.  It  is  possible  that  this  might
400              change  in  the  future so that ssm will be able to activate the
401              volume directly without the extra step.
402
403       device The crypt backend does not require a special device to  be  cre‐
404              ated on.
405
406   MD backend
407       MD  backend  in ssm is currently limited to only gather the information
408       about MD volumes in the system. You can not create or manage MD volumes
409       or pools, but this functionality will be extended in the future.
410
411   Multipath backend
412       Multipath backend in ssm is currently limited to only gather the infor‐
413       mation about multipath volumes in the system. You  can  not  create  or
414       manage  multipath  volumes or pools, but this functionality will be ex‐
415       tended in the future.
416

EXAMPLES

418       List system storage information:
419
420          # ssm list
421
422       List all pools in the system:
423
424          # ssm list pools
425
426       Create a new 100GB volume with the default lvm backend  using  /dev/sda
427       and /dev/sdb with xfs file system:
428
429          # ssm create --size 100G --fs xfs /dev/sda /dev/sdb
430
431       Create  a  new  volume with a btrfs backend using /dev/sda and /dev/sdb
432       and let the volume to be RAID 1:
433
434          # ssm -b btrfs create --raid 1 /dev/sda /dev/sdb
435
436       Using the lvm backend create a RAID 0 volume with devices /dev/sda  and
437       /dev/sdb  with  128kB  stripe  size,  ext4  file system and mount it on
438       /home:
439
440          # ssm create --raid 0 --stripesize 128k /dev/sda /dev/sdb /home
441
442       Create a new thinly provisioned volume with a lvm backend using devices
443       /dev/sda and /dev/sdb using --virtual-size option:
444
445          # ssm create --virtual-size 1T /dev/sda /dev/sdb
446
447       Create  a  new  thinly provisioned volume with a defined thin pool size
448       and devices /dev/sda and /dev/sdb:
449
450          # ssm create --size 50G --virtual-size 1T /dev/sda /dev/sdb
451
452       Extend btrfs volume btrfs_pool by 500GB and use /dev/sdc  and  /dev/sde
453       to cover the resize:
454
455          # ssm resize -s +500G btrfs_pool /dev/sdc /dev/sde
456
457       Shrink volume /dev/lvm_pool/lvol001 by 1TB:
458
459          # ssm resize -s-1t /dev/lvm_pool/lvol001
460
461       Remove  /dev/sda  device  from the pool, remove the btrfs_pool pool and
462       also remove the volume /dev/lvm_pool/lvol001:
463
464          # ssm remove /dev/sda btrfs_pool /dev/lvm_pool/lvol001
465
466       Take a snapshot of the btrfs volume btrfs_pool:my_volume:
467
468          # ssm snapshot btrfs_pool:my_volume
469
470       Add devices /dev/sda and /dev/sdb into the btrfs_pool pool:
471
472          # ssm add -p btrfs_pool /dev/sda /dev/sdb
473
474       Mount btrfs subvolume btrfs_pool:vol001 on /mnt/test:
475
476          # ssm mount btrfs_pool:vol001 /mnt/test
477

ENVIRONMENT VARIABLES

479       SSM_DEFAULT_BACKEND
480              Specify which backend will be used by default. This can be over‐
481              ridden  by  specifying  the  -b or --backend argument. Currently
482              only lvm and btrfs are supported.
483
484       SSM_LVM_DEFAULT_POOL
485              Name of the default lvm pool to be used if the -p or --pool  ar‐
486              gument is omitted.
487
488       SSM_BTRFS_DEFAULT_POOL
489              Name  of  the  default btrfs pool to be used if the -p or --pool
490              argument is omitted.
491
492       SSM_PREFIX_FILTER
493              When this is set, ssm will filter out all devices,  volumes  and
494              pools  whose  name  does  not start with this prefix. It is used
495              mainly in the ssm test suite to make sure that we do not  scram‐
496              ble the local system configuration.
497

LICENCE

499       (C)2017  Red  Hat, Inc., Jan Tulak <jtulak@redhat.com> (C)2011 Red Hat,
500       Inc., Lukas Czerner <lczerner@redhat.com>
501
502       This program is free software: you can redistribute it and/or modify it
503       under  the  terms of the GNU General Public License as published by the
504       Free Software Foundation, either version 2 of the License, or (at  your
505       option) any later version.
506
507       This  program  is  distributed  in the hope that it will be useful, but
508       WITHOUT ANY  WARRANTY;  without  even  the  implied  warranty  of  MER‐
509       CHANTABILITY  or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General
510       Public License for more details.
511
512       You should have received a copy of the GNU General Public License along
513       with this program.  If not, see <http://www.gnu.org/licenses/>.
514

REQUIREMENTS

516       Python  2.6 or higher is required to run this tool. System Storage Man‐
517       ager can only be run as root since most of the  commands  require  root
518       privileges.
519
520       There  are  other  requirements  listed below, but note that you do not
521       necessarily need all dependencies for all backends. However if some  of
522       the  tools  required  by  a  backend are missing, that backend will not
523       work.
524
525   Python modules
526       • argparse
527
528       • atexit
529
530       • base64
531
532       • datetime
533
534       • fcntl
535
536       • getpass
537
538       • os
539
540       • pwquality
541
542       • re
543
544       • socket
545
546       • stat
547
548       • struct
549
550       • subprocess
551
552       • sys
553
554       • tempfile
555
556       • termios
557
558       • threading
559
560       • tty
561
562   System tools
563       • tune2fs
564
565       • fsck.SUPPORTED_FS
566
567       • resize2fs
568
569       • xfs_db
570
571       • xfs_check
572
573       • xfs_growfs
574
575       • mkfs.SUPPORTED_FS
576
577       • which
578
579       • mount
580
581       • blkid
582
583       • wipefs
584
585       • dd
586
587   Lvm backend
588       • lvm2 binaries
589
590       Some distributions (e.g. Debian) have thin provisioning tools  for  LVM
591       as  an optional dependency, while others install it automatically. Thin
592       provisioning without these tools installed is not supported by SSM.
593
594   Btrfs backend
595       • btrfs progs
596
597   Crypt backend
598       • dmsetup
599
600       • cryptsetup
601
602   Multipath backend
603       • multipath
604

AVAILABILITY

606       System       storage       manager       is       available        from
607       http://system-storage-manager.github.io.    You    can   subscribe   to
608       storagemanager-devel@lists.sourceforge.net to follow the current devel‐
609       opment.
610

AUTHOR

612       Jan Ťulák <jtulak@redhat.com>, Lukáš Czerner <lczerner@redhat.com>
613
615       2021, Red Hat, Inc., Jan Ťulák <jtulak@redhat.com>, Lukáš Czerner <lcz‐
616       erner@redhat.com>
617
618
619
620
6211.3                              Jul 23, 2021                           SSM(8)
Impressum