feat: Add how-to guides on retrieving object storage utilization

Explain how to retrieve the total number of objects and their
cumulative size in a bucket (S3 API) or container (Swift API).

docs/howto/object-storage/s3/.pages

@@ -8,3 +8,4 @@ nav:
   - object-lock.md
   - versioning.md
   - "Object encryption (SSE-C)": sse-c.md
+  - utilization.md

docs/howto/object-storage/s3/utilization.md

@@ -0,0 +1,94 @@
+---
+description: A number of options exist to show object storage utilization.
+---
+# Object storage utilization
+
+You may be interested in the number of objects, or their cumulative size, currently held in a bucket.
+
+
+## Prerequisites
+
+In order to show the number or cumulative size of objects in a bucket, you must install `aws`, `mc`, or `s3cmd`, and [configure it with working credentials](credentials.md).
+
+
+## Showing the number of objects in a bucket
+
+To show the number of objects in a given bucket, use one of the following commands:
+
+=== "aws"
+    ```bash
+    aws --profile <region> \
+      s3 ls \
+      --recursive \
+      --summarize \
+      s3://<bucket>
+    ```
+    The object count is in the line prefixed with `Total Objects`, at the end of the output.
+=== "mc"
+    ```bash
+    mc ls <region>/<bucket> \
+      --recursive \
+      --summarize
+    ```
+    The object count is in the line prefixed with `Total Objects`, at the end of the output.
+
+    Alternatively, you may also use the `du` subcommand:
+    ```bash
+    mc du <region>/<bucket>
+    ```
+    Here, the object count is the second column of the output.
+=== "s3cmd"
+    ```bash
+    s3cmd -c ~/.s3cfg-<region> \
+      du \
+      s3://<bucket> \
+    ```
+    The object count is the second column of the output.
+
+## Showing the total size of objects in a bucket
+
+To show the overall size of all objects in a given bucket, use one of the following commands:
+
+=== "aws"
+    You use the same command as for counting objects:
+    ```bash
+    aws --profile <region> \
+      s3 ls \
+      --recursive \
+      --summarize \
+      s3://<bucket>
+    ```
+    The total object size is in the line prefixed with `Total Size`, at the end of the output.
+
+    By default, the total size is given in bytes.
+    If you prefer more sensible units, add the `--human-readable` option:
+    ```bash
+    aws --profile <region> \
+      s3 ls \
+      --recursive \
+      --summarize \
+      --human-readable
+      s3://<bucket>
+    ```
+=== "mc"
+    You could use the same command as for counting objects:
+    ```bash
+    mc ls <region>/<bucket> \
+      --recursive \
+      --summarize
+    ```
+    The total object size is in the line prefixed with `Total Size`, at the end of the output.
+    It is shown in KiB, MiB, GiB, or TiB, and the value shown may thus be approximate.
+
+    Alternatively, you may also use the `du` subcommand:
+    ```bash
+    mc du <region>/<bucket>
+    ```
+    The total object size is the first column of the output.
+=== "s3cmd"
+    ```bash
+    s3cmd -c ~/.s3cfg-<region> \
+      du \
+      s3://<bucket>
+    ```
+    The total object size is the first column of the output.

docs/howto/object-storage/swift/.pages

@@ -6,3 +6,4 @@ nav:
   - tempurl.md
   - expiry.md
   - versioning.md
+  - utilization.md

docs/howto/object-storage/swift/utilization.md

@@ -0,0 +1,48 @@
+---
+description: A number of options exist to show object storage utilization.
+---
+# Object storage utilization
+
+You may be interested in the number of objects, or their cumulative size, currently held in a container.
+
+
+## Prerequisites
+
+In order to create a Swift container, be sure that you have [installed and configured](index.md) the required command-line interface (CLI) tools.
+
+
+## Showing the number of objects in a container
+
+To show the number of objects in a given container, use one of the following commands:
+
+=== "OpenStack CLI"
+    ```bash
+    openstack container show <container> -c object_count
+    ```
+=== "Swift CLI"
+    ```bash
+    swift stat <container>
+    ```
+    The object count is in the line prefixed with `Objects`.
+
+
+## Showing the total size of objects in a container
+
+To show the overall size of all objects in a given container, use one of the following commands:
+
+=== "OpenStack CLI"
+    ```bash
+    openstack container show <container> -c bytes_used
+    ```
+    The total object size is always given in bytes.
+=== "Swift CLI"
+    ```bash
+    swift stat <container>
+    ```
+    The total object size is in the line prefixed with `Bytes`.
+
+    To scale the total size output to human-readable units, add the `--lh` option:
+
+    ```bash
+    swift stat --lh <container>
+    ```