mdadm Resource
This page is generated from the Chef Infra Client source code.To suggest a change, edit the mdadm.rb file and submit a pull request to the Chef Infra Client repository.
Use the mdadm resource to manage RAID devices in a Linux environment using the mdadm utility. The mdadm resource will create and assemble an array, but it will not create the config file that is used to persist the array upon reboot. If the config file is required, it must be done by specifying a template with the correct array layout, and then by using the mount provider to create a file systems table (fstab) entry.
Syntax
The full syntax for all of the properties that are available to the mdadm resource is:
mdadm 'name' do
bitmap String
chunk Integer # default value: 16
devices Array # default value: []
layout String
level Integer # default value: 1
metadata String # default value: "0.90"
raid_device String # default value: 'name' unless specified
action Symbol # defaults to :create if not specified
end
where:
mdadm
is the resource.name
is the name given to the resource block.action
identifies which steps Chef Infra Client will take to bring the node into the desired state.bitmap
,chunk
,devices
,layout
,level
,metadata
, andraid_device
are the properties available to this resource.
Actions
The mdadm resource has the following actions:
:assemble
- Assemble a previously created array into an active array.
:create
- Create an array with per-device superblocks. If an array already exists (but does not match), update that array to match. (default)
:nothing
- This resource block does not act unless notified by another resource to take action. Once notified, this resource block either runs immediately or is queued up to run at the end of a Chef Infra Client run.
:stop
- Stop an active array.
Properties
The mdadm resource has the following properties:
bitmap
- Ruby Type: String
The path to a file in which a write-intent bitmap is stored.
chunk
- Ruby Type: Integer | Default Value:
16
The chunk size. This property should not be used for a RAID 1 mirrored pair (i.e. when the
level
property is set to1
).
devices
- Ruby Type: Array | Default Value:
[]
The devices to be part of a RAID array.
layout
- Ruby Type: String
The RAID5 parity algorithm. Possible values:
left-asymmetric
(orla
),left-symmetric
(or ls),right-asymmetric
(orra
), orright-symmetric
(orrs
).
level
- Ruby Type: Integer | Default Value:
1
The RAID level.
metadata
- Ruby Type: String | Default Value:
0.90
The superblock type for RAID metadata.
raid_device
- Ruby Type: String | Default Value:
The resource block's name
An optional property to specify the name of the RAID device if it differs from the resource block’s name.
Common Resource Functionality
Chef resources include common properties, notifications, and resource guards.
Common Properties
The following properties are common to every resource:
compile_time
Ruby Type: true, false | Default Value:
false
Control the phase during which the resource is run on the node. Set to true to run while the resource collection is being built (the
compile phase
). Set to false to run while Chef Infra Client is configuring the node (theconverge phase
).ignore_failure
Ruby Type: true, false, :quiet | Default Value:
false
Continue running a recipe if a resource fails for any reason.
:quiet
will not display the full stack trace and the recipe will continue to run if a resource fails.retries
Ruby Type: Integer | Default Value:
0
The number of attempts to catch exceptions and retry the resource.
retry_delay
Ruby Type: Integer | Default Value:
2
The delay in seconds between retry attempts.
sensitive
Ruby Type: true, false | Default Value:
false
Ensure that sensitive resource data is not logged by Chef Infra Client.
Notifications
notifies
Ruby Type: Symbol, 'Chef::Resource[String]'
A resource may notify another resource to take action when its state changes. Specify a
'resource[name]'
, the:action
that resource should take, and then the:timer
for that action. A resource may notify more than one resource; use anotifies
statement for each resource to be notified.If the referenced resource does not exist, an error is raised. In contrast,
subscribes
will not fail if the source resource is not found.
A timer specifies the point during a Chef Infra Client run at which a notification is run. The following timers are available:
:before
Specifies that the action on a notified resource should be run before processing the resource block in which the notification is located.
:delayed
Default. Specifies that a notification should be queued up, and then executed at the end of a Chef Infra Client run.
:immediate
,:immediately
Specifies that a notification should be run immediately, for each resource notified.
The syntax for notifies
is:
notifies :action, 'resource[name]', :timer
subscribes
Ruby Type: Symbol, 'Chef::Resource[String]'
A resource may listen to another resource, and then take action if the
state of the resource being listened to changes. Specify a
'resource[name]'
, the :action
to be taken, and then the :timer
for
that action.
Note that subscribes
does not apply the specified action to the
resource that it listens to - for example:
file '/etc/nginx/ssl/example.crt' do
mode '0600'
owner 'root'
end
service 'nginx' do
subscribes :reload, 'file[/etc/nginx/ssl/example.crt]', :immediately
end
In this case the subscribes
property reloads the nginx
service
whenever its certificate file, located under
/etc/nginx/ssl/example.crt
, is updated. subscribes
does not make any
changes to the certificate file itself, it merely listens for a change
to the file, and executes the :reload
action for its resource (in this
example nginx
) when a change is detected.
If the other resource does not exist, the subscription will not raise an
error. Contrast this with the stricter semantics of notifies
, which
will raise an error if the other resource does not exist.
A timer specifies the point during a Chef Infra Client run at which a notification is run. The following timers are available:
:before
Specifies that the action on a notified resource should be run before processing the resource block in which the notification is located.
:delayed
Default. Specifies that a notification should be queued up, and then executed at the end of a Chef Infra Client run.
:immediate
,:immediately
Specifies that a notification should be run immediately, for each resource notified.
The syntax for subscribes
is:
subscribes :action, 'resource[name]', :timer
Guards
A guard property can be used to evaluate the state of a node during the execution phase of a Chef Infra Client run. Based on the results of this evaluation, a guard property is then used to tell Chef Infra Client if it should continue executing a resource. A guard property accepts either a string value or a Ruby block value:
- A string is executed as a shell command. If the command returns
0
, the guard is applied. If the command returns any other value, then the guard property is not applied. String guards in a powershell_script run Windows PowerShell commands and may returntrue
in addition to0
. - A block is executed as Ruby code that must return either
true
orfalse
. If the block returnstrue
, the guard property is applied. If the block returnsfalse
, the guard property is not applied.
A guard property is useful for ensuring that a resource is idempotent by allowing that resource to test for the desired state as it is being executed, and then if the desired state is present, for Chef Infra Client to do nothing.
PropertiesThe following properties can be used to define a guard that is evaluated during the execution phase of a Chef Infra Client run:
not_if
Prevent a resource from executing when the condition returns
true
.only_if
Allow a resource to execute only if the condition returns
true
.
Examples
The following examples demonstrate various approaches for using the mdadm resource in recipes:
Create and assemble a RAID 0 array
The mdadm command can be used to create RAID arrays. For example, a RAID 0 array named /dev/md0 with 10 devices would have a command similar to the following:
mdadm --create /dev/md0 --level=0 --raid-devices=10 /dev/s01.../dev/s10
where /dev/s01 .. /dev/s10 represents 10 devices (01, 02, 03, and so on). This same command, when expressed as a recipe using the mdadm resource, would be similar to:
mdadm '/dev/md0' do
devices [ '/dev/s01', ... '/dev/s10' ]
level 0
action :create
end
(again, where /dev/s01 .. /dev/s10 represents devices /dev/s01, /dev/s02, /dev/s03, and so on).
Create and assemble a RAID 1 array
mdadm '/dev/md0' do
devices [ '/dev/sda', '/dev/sdb' ]
level 1
action [ :create, :assemble ]
end
Create and assemble a RAID 5 array
The mdadm command can be used to create RAID arrays. For example, a RAID 5 array named /dev/sd0 with 4, and a superblock type of 0.90 would be similar to:
mdadm '/dev/sd0' do
devices [ '/dev/s1', '/dev/s2', '/dev/s3', '/dev/s4' ]
level 5
metadata '0.90'
chunk 32
action :create
end