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Use Cases

A DAOS pool is a persistent storage reservation that is allocated to a project or specific job. Pools are allocated, shrunk, grown and destroyed by the administrators.

The typical workflow consists of:

  • New project members meet and define storage requirements including space, bandwidth, IOPS & data protection needs.

  • Administrators collect those requirements, create a pool for the new project and set relevant ACL to grant access to project members.

  • Administrators notify the project members that the pool has been created and provide the pool label to the users.

Users can then create containers (i.e. datasets or buckets) in their pool. Containers will share the pool space and have their own ACL to be managed by the container owner.

Since pool creation is relatively fast, it is also possible to integrate it with the resource manager to create and ingest data into an ephemeral pool for each job.

Another alternative use case is to emulate a parallel file system by creating one big pool with a single POSIX container to be accessed by all users.

daos(1) Utility

The daos(1) utility is built over the libdaos library and is the primary command-line interface for users to interact with their pool and containers. It supports a -j option to generate a parseable json output.

The daos utility follows the same syntax as dmg (reserved for administrator) and takes a resource (e.g. pool, container, filesystem) and a command (e.g. query, create, destroy) plus a set of command-specific options.

$ daos --help

daos is a tool that can be used to manage/query pool content,
create/query/manage/destroy a container inside a pool, copy data
between a POSIX container and a POSIX filesystem, clone a DAOS container,
or query/manage an object inside a container.

Application Options:
      --debug    enable debug output
      --verbose  enable verbose output (when applicable)
  -j, --json     enable JSON output

Help Options:
  -h, --help     Show this help message

Available commands:
  container   perform tasks related to DAOS containers (aliases: cont)
  filesystem  POSIX filesystem operations (aliases: fs)
  object      DAOS object operations (aliases: obj)
  pool        perform tasks related to DAOS pools
  version     print daos version

Accessing Your Pool

Access Validation

To validate the pool can be successfully accessed prior to running applications, the daos pool autotest suite can be executed.

To run it against a pool labeled tank, run the following command:

$ daos pool autotest tank
Step Operation               Status Time(sec) Comment
  0  Initializing DAOS          OK      0.000
  1  Connecting to pool         OK      0.070
  2  Creating container         OK      0.000  uuid = ba5c6a78-6ddc-4c7e-a73b-b7574c8d85b8
  3  Opening container          OK      0.060
 10  Generating 1M S1 layouts   OK      2.960
 11  Generating 10K SX layouts  OK      0.130
 20  Inserting 1M 128B values   OK     27.350
 21  Reading 128B values back   OK     26.020
 24  Inserting 1M 4KB values    OK     54.410
 25  Reading 4KB values back    OK     54.380
 28  Inserting 100K 1MB values  OK    605.870
 29  Reading 1MB values back    OK    680.360
 96  Closing container          OK      0.000
 97  Destroying container       OK      0.030
 98  Disconnecting from pool    OK      0.010
 99  Tearing down DAOS          OK      0.000

All steps passed.


The command is executed in a development environment, performance differences will vary, based on your system.


Smaller pools may show DER_NOSPACE(-1007): 'No space on storage target'

Querying the Pool

Once a pool has been assigned to your project (labeled tank in the example below), you can verify how much space was allocated to your project via the daos pool query <pool_label> command as follows:

$ daos pool query tank
Pool ada29109-0589-4fb8-9726-1252faea5d01, ntarget=32, disabled=0, leader=0, version=1
Pool space info:
- Target(VOS) count:32
- SCM:
  Total size: 50 GB
  Free: 50 GB, min:1.6 GB, max:1.6 GB, mean:1.6 GB
- NVMe:
  Total size: 0 B
  Free: 0 B, min:0 B, max:0 B, mean:0 B
Rebuild idle, 0 objs, 0 recs

In addition to the space information, details on the pool rebuild status and number of targets is also provided.

This information can also be retrieved programmatically via the daos_pool_query() function of the libdaos library and python equivalent.

Pool Attributes

Project-wise information can be stored in pool user attributes (not to be confused with pool properties). Pool attributes can be manipulated via the daos pool [set|get|list|del]-attr commands.

$ daos pool set-attr tank project_deadline "September 30, 2025"

$ daos pool list-attr tank
Attributes for pool 004abf7c-26c8-4cba-9059-8b3be39161fc:

$ daos pool get-attr tank project_deadline
Attributes for pool 004abf7c-26c8-4cba-9059-8b3be39161fc:
Name             Value
----             -----
project_deadline September 30, 2025

$ daos pool del-attr tank project_deadline

$ daos pool list-attr tank
Attributes for pool 004abf7c-26c8-4cba-9059-8b3be39161fc:
  No attributes found.

Pool attributes can be manipulaged programmatically via the daos_pool_[get|get|list|del]_attr() functions exported by the libdaos library and python equivalent (see PyDAOS).

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