This article explains:
How to discover the ID of your block device
Block devices do not exist apart from the physical or virtual machines to which they are attached. Finding the ID of the block device that interests you requires starting with a particular machine, in a command form that looks like this:
maas $PROFILE block-devices read $SYSTEM_ID \
| jq -r '(["system_id","block_device_id","path","avail_size"]
|(.,map(length*"-"))),(.[]|[.system_id,.id,.path,.available_size])
| @tsv' | column -t
For example:
maas admin block-devices read qk4b3g \
| jq -r '(["system_id","block_device_id","path","avail_size"]
|(.,map(length*"-"))),(.[]|[.system_id,.id,.path,.available_size])
| @tsv' | column -t
This example would produce output that looks something like this:
system_id block_device_id path avail_size
--------- --------------- ---- ----------
qk4b3g 10 /dev/disk/by-dname/sda 0
The path component is printed to help you confirm that you are choosing the right block device, when there are several present. The avail-size column will tell you whether you can operate on that block device at all: If the available size is “0,” for example, you can’t set a block device tag on any part of that drive. Instead, you’d want to see something like this:
system_id block_device_id path avail_size
--------- --------------- ---- ----------
xn8taa 8 /dev/disk/by-dname/sda 1996488704
How to assign tags to a block device
You can only assign tags to a block device that is available. You can find out whether the block device is available at all when you discover its ID.
To assign an existing tag to a block device, you would type a command formulated like this:
maas $PROFILE block-device add-tag $SYSTEM_ID $BLOCK_DEVICE_ID tag=$TAG_NAME
If you’re not sure about the ID of your block device, you can look it up.
For example:
maas admin block-device add-tag xn8taa 8 tag=farquar
If this command succeeds, it will display Success, followed by a JSON sequence describing the new state of the block device.
Note that if you try to add a tag to a block device that is not available, that is, to a block device that is in use, you will get a result like this:
Not Found
How to remove tags from a block device
You can only remove tags from a block device that is available. You can find out whether the block device is available at all when you discover its ID.
To remove an assigned tag from a block device, you would type a command formulated like this:
maas $PROFILE block-device remove-tag $SYSTEM_ID $BLOCK_DEVICE_ID tag=$TAG_NAME
If you’re not sure about the ID of your block device, you can look it up.
For example:
maas admin block-device remove-tag xn8taa 8 tag=farquar
If this command succeeds, it will display Success, followed by a JSON sequence describing the new state of the block device.
Note that if you try to remove a tag from a block device that is not available, that is, from a block device that is in use, you will get a result like this:
Not Found
How to list tags for all block devices
To list tags for all block devices associated with a physical or virtual machine, you can use a command of this form:
maas $PROFILE block-devices read $SYSTEM_ID | jq -r '(["id","tags"]|(.,map(length*"-"))),(.[]|[.id,.tags[]]) | @tsv' | column -t
For example:
maas admin block-devices read xn8taa | jq -r '(["id","tags"]|(.,map(length*"-"))),(.[]|[.id,.tags[]]) | @tsv' | column -t
This command would produce output similar to this:
id tags
-- ----
8 hello ssd trinkoplinko
How to view tags for one block device
To view tags for one specific block device, you can enter a command like this:
maas $PROFILE block-device read $SYSTEM_ID $BLOCK_DEVICE_ID | jq -r '(["id","tags"]|(.,map(length*"-"))),([.id,.tags[]]) | @tsv' | column -t
If you’re not sure about the ID of your block device, you can look it up.
For example:
maas admin block-device read xn8taa 8 | jq -r '(["id","tags"]|(.,map(length*"-"))),([.id,.tags[]]) | @tsv' | column -t
This command would produce output similar to this:
id tags
-- ----
8 hello ssd trinkoplinko
9 20gig ssd
10 250Gs ssd
How to discover the ID of your partition
Partitions do not exist apart from the block devices on which they reside. Finding the ID of the partition that interests you requires starting with a particular machine and block device, similar to this command:
maas $PROFILE partitions read $SYSTEM_ID $BLOCK_DEVICE_ID \
| jq -r '(["system_id","block_dev_id","part_id","path"]
|(.,map(length*"-"))),(.[]|[.system_id,.device_id,.id,.path])
|@tsv' | column -t
For example:
maas admin partitions read xn8taa 8 \
| jq -r '(["system_id","block_dev_id","part_id","path"]
|(.,map(length*"-"))),(.[]|[.system_id,.device_id,.id,.path])
|@tsv' | column -t
```
This example would produce output that looks something like this:
```nohighlight
system_id block_dev_id part_id path
--------- ------------ ------- ----
xn8taa 8 67 /dev/disk/by-dname/sda-part1
The path component is printed to help you confirm that you are choosing the right partition, when there are several present.
How to assign tags to a partition
You can only assign tags to a partition that is available. To assign an existing tag to a partition, you would type a command formulated like this:
maas $PROFILE partition add-tag $SYSTEM_ID $BLOCK_DEVICE_ID $PARTITION_ID tag=$TAG_NAME
If you’re not sure about the ID of your partition, you can look it up.
For example:
maas admin partition add-tag xn8taa 8 67 tag=farquar
If this command succeeds, it will display Success, followed by a JSON sequence describing the new state of the partition.
Note that if you try to add a tag to a partition that is not available, that is, to a partition that is in use, you will get a result like this:
Not Found
How to remove tags from a partition
You can only remove tags from a partition that is available. To remove a existing tag from a partition, you would type a command formulated like this:
maas $PROFILE partition remove-tag $SYSTEM_ID $BLOCK_DEVICE_ID $PARTITION_ID tag=$TAG_NAME
If you’re not sure about the ID of your partition, you can look it up.
For example:
maas admin partition remove-tag xn8taa 8 67 tag=farquar
If this command succeeds, it will display Success, followed by a JSON sequence describing the new state of the partition.
Note that if you try to remove a tag from a partition that is not available, that is, from a partition that is in use, you will get a result like this:
Not Found
On the other hand, if you try to remove a tag that is not assigned to the partition you’ve chosen, MAAS will simply return Success, followed by a JSON sequence describing the current state of the partition.
How to list tags for all partitions
To list tags for all partitions of a particular block device, use a command like this one:
maas $PROFILE partitions read $SYSTEM_ID $BLOCK_DEVICE_ID \
| jq -r '(["id","tags"]
|(.,map(length*"-"))),(.[]|[.id,.tags[]])
| @tsv' | column -t
For example:
maas admin partitions read xn8taa 8 \
| jq -r '(["id","tags"]
|(.,map(length*"-"))),(.[]|[.id,.tags[]])
| @tsv' | column -t
A command like this should return output similar to the following:
id tags
-- ----
54 farquar swap opendisk
67 foobar farquar
97 foobar
How to view tags for one partition
To view tags for one partition, enter a command similar to this:
maas $PROFILE partition read $SYSTEM_ID $BLOCK_DEVICE_ID $PARTITION_ID | jq -r '(["id","tags"]|(.,map(length*"-"))),([.id,.tags[]]) | @tsv' | column -t
If you’re not sure about the ID of your partition, you can look it up.
For example:
maas admin partition read xn8taa 8 67 | jq -r '(["id","tags"]|(.,map(length*"-"))),([.id,.tags[]]) | @tsv' | column -t
This command should produce output similar to this:
id tags
-- ----
67 foobar farquar