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\begin{verbatim}
Thorough documentation is in mars-manual.pdf. Please use the PDF manual
as authoritative reference! Here is only a short summary of the most
important sub-commands / options:
marsadm [<global_options>] <command> [<resource_name> | all | <args> ]
marsadm [<global_options>] view[-<macroname>] [<resource_name> | all ]
<global_option> =
--force
Skip safety checks.
Use this only when you really know what you are doing!
Warning! This is dangerous! First try --dry-run.
Not combinable with 'all'.
--ignore-sync
Allow primary handover even when some sync is running somewhere.
This is less rude than --force because it checks for all else
preconditions.
--dry-run
Don't modify the symlink tree, but tell what would be done.
Use this before starting potentially harmful actions such as
'delete-resource'.
--verbose
Increase speakyness of some commands.
--logger=/path/to/usr/bin/logger
Use an alternative syslog messenger.
When empty, disable syslogging.
--max-deletions=<number>
When your network or your firewall rules are defective over a
longer time, too many deletion links may accumulate at
/mars/todo-global/delete-* and sibling locations.
This limit is preventing overflow of the filesystem as well
as overloading the worker threads.
--thresh-logfiles=<number>
--thresh-logsize=<number>
Prevention of too many small logfiles when secondaries are not
catching up. When more than thresh-logfiles are already present,
the next one is only created when the last one has at least
size thresh-logsize (in units of GB).
--timeout=<seconds>
Abort safety checks after timeout with an error.
When giving 'all' as resource agument, this works for each
resource independently.
--window=<seconds>
Treat other cluster nodes as healthy when some communcation has
occured during the given time window.
--threshold=<bytes>
Some macros like 'fetch-threshold-reached' use this for determining
their sloppyness.
--host=<hostname>
Act as if the command was running on cluster node <hostname>.
Warning! This is dangerous! First try --dry-run
--backup-dir=</absolute_path>
Only for experts.
Used by several special commands like merge-cluster, split-cluster
etc for creating backups of important data.
--ip=<ip>
Override the IP address stored in the symlink tree, as well as
the default IP determined from the list of network interfaces.
Usually you will need this only at 'create-cluster' or
'join-cluster' for resolving ambiguities.
--ssh-port=<port_nr>
Override the default ssh port (22) for ssh and rsync.
Useful for running {join,merge}-cluster on non-standard ssh ports.
--ssh-opts="<ssh_commandline_options>"
Override the default ssh commandline options. Also used for rsync.
--macro=<text>
Handy for testing short macro evaluations at the command line.
<command> =
attach
usage: attach <resource_name>
Attaches the local disk (backing block device) to the resource.
The disk must have been previously configured at
{create,join}-resource.
When designated as a primary, /dev/mars/$res will also appear.
This does not change the state of {fetch,replay}.
For a complete local startup of the resource, use 'marsadm up'.
cat
usage: cat <path>
Print internal debug output in human readable form.
Numerical timestamps and numerical error codes are replaced
by more readable means.
Example: marsadm cat /mars/5.total.status
connect
usage: connect <resource_name>
See resume-fetch-local.
connect-global
usage: connect-global <resource_name>
Like resume-fetch-local, but affects all resource members
in the cluster (remotely).
connect-local
usage: connect-local <resource_name>
See resume-fetch-local.
create-cluster
usage: create-cluster (no parameters)
This must be called exactly once when creating a new cluster.
Don't call this again! Use join-cluster on the secondary nodes.
Please read the PDF manual for details.
create-resource
usage: create-resource <resource_name> </dev/lv/mydata>
(further syntax variants are described in the PDF manual).
Create a new resource out of a pre-existing disk (backing
block device) /dev/lv/mydata (or similar).
The current node will start in primary role, thus
/dev/mars/<resource_name> will appear after a short time, initially
showing the same contents as the underlying disk /dev/lv/mydata.
It is good practice to name the resource <resource_name> and the
disk name identical.
cron
usage: cron (no parameters)
Do all necessary regular housekeeping tasks.
This is equivalent to log-rotate all; sleep 5; log-delete-all all.
delete-resource
usage: delete-resource <resource_name>
CAUTION! This is dangerous when the network is somehow
interrupted, or when damaged nodes are later re-surrected
in any way.
Precondition: the resource must no longer have any members
(see leave-resource).
This is only needed when you _insist_ on re-using a damaged
resource for re-creating a new one with exactly the same
old <resource_name>.
HINT: best practice is to not use this, but just create a _new_
resource with a new <resource_name> out of your local disks.
Please read the PDF manual on potential consequences.
detach
usage: detach <resource_name>
Detaches the local disk (backing block device) from the
MARS resource.
Caution! you may read data from the local disk afterwards,
but ensure that no data is written to it!
Otherwise, you are likely to produce harmful inconsistencies.
When running in primary role, /dev/mars/$res will also disappear.
This does not change the state of {fetch,replay}.
For a complete local shutdown of the resource, use 'marsadm down'.
disconnect
usage: disconnect <resource_name>
See pause-fetch-local.
disconnect-global
usage: disconnect-global <resource_name>
Like pause-fetch-local, but affects all resource members
in the cluster (remotely).
disconnect-local
usage: disconnect-local <resource_name>
See pause-fetch-local.
down
usage: down <resource_name>
Shortcut for detach + pause-sync + pause-fetch + pause-replay.
get-emergency-limit
usage: get-emergency-limit <resource_name>
Counterpart of set-emergency-limit (per-resource emergency limit)
get-sync-limit-value
usage: get-sync-limit-value (no parameters)
For retrieval of the value set by set-sync-limit-value.
get-systemd-unit
usage: get-systemd-unit <resource_name>
Show the system units (for start and stop), or empty when unset.
invalidate
usage: invalidate <resource_name>
Only useful on a secondary node.
Forces MARS to consider the local replica disk as being
inconsistent, and therefore starting a fast full-sync from
the currently designated primary node (which must exist;
therefore avoid the 'secondary' command).
This is usually needed for resolving emergency mode.
When having k=2 replicas, this can be also used for
quick-and-simple split-brain resolution.
In other cases, or when the split-brain is not resolved by
this command, please use the 'leave-resource' / 'join-resource'
method as described in the PDF manual (in the right order as
described there).
join-cluster
usage: join-cluster <hostname_of_primary>
Establishes a new cluster membership.
This must be called once on any new cluster member.
This is a prerequisite for join-resource.
join-resource
usage: join-resource <resource_name> </dev/lv/mydata>
(further syntax variants are described in the PDF manual).
The resource <resource_name> must have been already created on
another cluster node, and the network must be healthy.
The contents of the local replica disk /dev/lv/mydata will be
overwritten by the initial fast full sync from the currently
designated primary node.
After the initial full sync has finished, the current host will
act in secondary role.
For details on size constraints etc, refer to the PDF manual.
leave-cluster
usage: leave-cluster (no parameters)
This can be used for final deconstruction of a cluster member.
Prior to this, all resources must have been left
via leave-resource.
Notice: this will never destroy the cluster UID on the /mars/
filesystem.
Please read the PDF manual for details.
leave-resource
usage: leave-resource <resource_name>
Precondition: the local host must be in secondary role.
Stop being a member of the resource, and thus stop all
replication activities. The status of the underlying disk
will remain in its current state (whatever it is).
log-delete
usage: log-delete <resource_name>
When possible, globally delete all old transaction logfiles which
are known to be superflous, i.e. all secondaries no longer need
to replay them.
This must be regularly called by a cron job or similar, in order
to prevent overflow of the /mars/ directory.
For regular maintainance cron jobs, please prefer 'marsadm cron'.
For details and best practices, please refer to the PDF manual.
log-delete-all
usage: log-delete-all <resource_name>
Alias for log-delete
log-delete-one
usage: log-delete-one <resource_name>
When possible, globally delete at most one old transaction logfile
which is known to be superfluous, i.e. all secondaries no longer
need to replay it.
Hint: use this only for testing and manual inspection.
For regular maintainance cron jobs, please prefer cron
or log-delete-all.
log-purge-all
usage: log-purge-all <resource_name>
This is potentially dangerous.
Use this only if you are really desperate in trying to resolve a
split brain. Use this only after reading the PDF manual!
log-rotate
usage: log-rotate <resource_name>
Only useful at the primary side.
Start writing transaction logs into a new transaction logfile.
This should be regularly called by a cron job or similar.
For regular maintainance cron jobs, please prefer 'marsadm cron'.
For details and best practices, please refer to the PDF manual.
lowlevel-delete-host
usage: lowlevel-delete-host <resource_name>
Delete cluster member.
lowlevel-ls-host-ips
usage: lowlevel-ls-host-ips <resource_name>
List cluster member names and IP addresses.
lowlevel-set-host-ip
usage: lowlevel-set-host-ip <resource_name>
Set IP for host.
merge-cluster
usage: merge-cluster <hostname_of_other_cluster>
Precondition: the resource names of both clusters must be disjoint.
Create the union of two clusters, consisting of the
union of all machines, and the union of all resources.
The members of each resource are _not_ changed by this.
This is useful for creating a big "virtual LVM cluster" where
resources can be almost arbitrarily migrated between machines via
later join-resource / leave-resource operations.
merge-cluster-check
usage: merge-cluster-check <hostname_of_other_cluster>
Check whether the resources of both clusters are disjoint.
Useful for checking in advance whether merge-cluster would be
possible.
merge-cluster-list
usage: merge-cluster-list
Determine the local list of resources.
Useful for checking or analysis of merge-cluster disjointness by hand.
pause-fetch
usage: pause-fetch <resource_name>
See pause-fetch-local.
pause-fetch-global
usage: pause-fetch-global <resource_name>
Like pause-fetch-local, but affects all resource members
in the cluster (remotely).
pause-fetch-local
usage: pause-fetch-local <resource_name>
Stop fetching transaction logfiles from the current
designated primary.
This is independent from any {pause,resume}-replay operations.
Only useful on a secondary node.
pause-replay
usage: pause-replay <resource_name>
See pause-replay-local.
pause-replay-global
usage: pause-replay-global <resource_name>
Like pause-replay-local, but affects all resource members
in the cluster (remotely).
pause-replay-local
usage: pause-replay-local <resource_name>
Stop replaying transaction logfiles for now.
This is independent from any {pause,resume}-fetch operations.
This may be used for freezing the state of your replica for some
time, if you have enough space on /mars/.
Only useful on a secondary node.
pause-sync
usage: pause-sync <resource_name>
See pause-sync-local.
pause-sync-global
usage: pause-sync-global <resource_name>
Like pause-sync-local, but affects all resource members
in the cluster (remotely).
pause-sync-local
usage: pause-sync-local <resource_name>
Pause the initial data sync at current stage.
This has only an effect if a sync is actually running (i.e.
there is something to be actually synced).
Don't pause too long, because the local replica will remain
inconsistent during the pause.
Use this only for limited reduction of system load.
Only useful on a secondary node.
primary
usage: primary <resource_name>
Promote the resource into primary role.
This is necessary for /dev/mars/$res to appear on the local host.
Notice: by concept there can be only _one_ designated primary
in a cluster at the same time.
The role change is automatically distributed to the other nodes
in the cluster, provided that the network is healthy.
The old primary node will _automatically_ go
into secondary role first. This is different from DRBD!
With MARS, you don't need an intermediate 'secondary' command
for switching roles.
It is usually better to _directly_ switch the primary roles
between both hosts.
When --force is not given, a planned handover is started:
the local host will only become actually primary _after_ the
old primary is gone, and all old transaction logs have been
fetched and replayed at the new designated priamry.
When --force is given, no handover is attempted. A a consequence,
a split brain situation is likely to emerge.
Thus, use --force only after an ordinary handover attempt has
failed, and when you don't care about the split brain.
For more details, please refer to the PDF manual.
resize
usage: resize <resource_name>
Prerequisite: all underlying disks (usually /dev/vg/$res) must
have been already increased, e.g. at the LVM layer (cf. lvresize).
Causes MARS to re-examine all sizing constraints on all members of
the resource, and increase the global logical size of the resource
accordingly.
Shrinking is currently not yet implemented.
When successful, /dev/mars/$res at the primary will be increased
in size. In addition, all secondaries will start an incremental
fast full-sync to get the enlarged parts from the primary.
resume-fetch
usage: resume-fetch <resource_name>
See resume-fetch-local.
resume-fetch-global
usage: resume-fetch-global <resource_name>
Like resume-fetch-local, but affects all resource members
in the cluster (remotely).
resume-fetch-local
usage: resume-fetch-local <resource_name>
Start fetching transaction logfiles from the current
designated primary node, if there is one.
This is independent from any {pause,resume}-replay operations.
Only useful on a secondary node.
resume-replay
usage: resume-replay <resource_name>
See resume-replay-local.
resume-replay-global
usage: resume-replay-global <resource_name>
Like resume-replay-local, but affects all resource members
in the cluster (remotely).
resume-replay-local
usage: resume-replay-local <resource_name>
Restart replaying transaction logfiles, when there is some
data left.
This is independent from any {pause,resume}-fetch operations.
This should be used for unfreezing the state of your local replica.
Only useful on a secondary node.
resume-sync
usage: resume-sync <resource_name>
See resume-sync-local.
resume-sync-global
usage: resume-sync-global <resource_name>
Like resume-sync-local, but affects all resource members
in the cluster (remotely).
resume-sync-local
usage: resume-sync-local <resource_name>
Resume any initial / incremental data sync at the stage where it
had been interrupted by pause-sync.
Only useful on a secondary node.
secondary
usage: secondary <resource_name>
Promote all cluster members into secondary role, globally.
In contrast to DRBD, this is not needed as an intermediate step
for planned handover between an old and a new primary node.
The only reasonable usage is before the last leave-resource of the
last cluster member, immediately before leave-cluster is executed
for final deconstruction of the cluster.
In all other cases, please prefer 'primary' for direct handover
between cluster nodes.
Notice: 'secondary' sets the global designated primary node
to '(none)' which in turn prevents the execution of 'invalidate'
or 'join-resource' or 'resize' anywhere in the cluster.
Therefore, don't unnecessarily give 'secondary'!
set-emergency-limit
usage: set-emergency-limit <resource_name> <value>
Set a per-resource emergency limit for disk space in /mars.
See PDF manual for details.
set-sync-limit-value
usage: set-sync-limit-value <new_value>
Set the maximum number of resources which should by syncing
concurrently.
set-systemd-unit
usage: set-systemd-unit <resource_name> <start_unit_name> [<stop_unit_name>]
This activates the systemd template engine of marsadm.
Please read mars-manual.pdf on this.
When <stop_unit_name> is omitted, it will be treated equal to
<start_unit_name>.
split-cluster
usage: split-cluster (no parameters)
NOT OFFICIALLY SUPPORTED - ONLY FOR EXPERTS.
RTFS = Read The Fucking Sourcecode.
Use this only if you know what you are doing.
up
usage: up <resource_name>
Shortcut for attach + resume-sync + resume-fetch + resume-replay.
wait-cluster
usage: wait-resource [<resource_name>]
Waits until a ping-pong communication has succeeded in the
whole cluster (or only the members of <resource_name>).
NOTICE: this is extremely useful for avoiding races when scripting
in a cluster.
wait-connect
usage: wait-connect [<resource_name>]
See wait-cluster.
wait-resource
usage: wait-resource <resource_name>
[[attach|fetch|replay|sync][-on|-off]]
Wait until the given condition is met on the resource, locally.
wait-umount
usage: wait-umount <resource_name>
Wait until /dev/mars/<resource_name> has disappeared in the
cluster (even remotely).
Useful on both primary and secondary nodes.
<resource_name> = name of resource or "all" for all resources
<macroname> = <complex_macroname> | <primitive_macroname>
<complex_macroname> =
1and1
comminfo
commstate
cstate
default
default-global
diskstate
diskstate-1and1
dstate
fetch-line
fetch-line-1and1
flags
flags-1and1
outdated-flags
outdated-flags-1and1
primarynode
primarynode-1and1
replay-line
replay-line-1and1
replinfo
replinfo-1and1
replstate
replstate-1and1
resource-errors
resource-errors-1and1
role
role-1and1
state
status
sync-line
sync-line-1and1
syncinfo
syncinfo-1and1
todo-role
<primitive_macroname> =
deletable-size
device-opened
errno-text
Convert errno numbers (positive or negative) into human readable text.
get-log-status
get-resource-{fat,err,wrn}{,-count}
get-{disk,device}
is-{alive}
is-{split-brain,consistent,emergency,orphan}
occupied-size
present-{disk,device}
(deprecated, use *-present instead)
replay-basenr
replay-code
When negative, this indidates that a replay/recovery error has occurred.
rest-space
summary-vector
systemd-unit
tree
uuid
wait-{is,todo}-{attach,sync,fetch,replay,primary}-{on,off}
{alive,fetch,replay,work}-{timestamp,age,lag}
{all,the}-{pretty-,}{global-,}{{err,wrn,inf}-,}msg
{cluster,resource}-members
{disk,device}-present
{disk,resource,device}-size
{fetch,replay,work}-{lognr,logcount}
{get,actual}-primary
{is,todo}-{attach,sync,fetch,replay,primary}
{my,all}-resources
{sync,fetch,replay,work,syncpos}-{size,pos}
{sync,fetch,replay,work}-{rest,{almost-,threshold-,}reached,percent,permille,vector}
{sync,fetch,replay}-{rate,remain}
{time,real-time}
\end{verbatim}
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