Copilot commented on code in PR #12609:
URL: https://github.com/apache/trafficserver/pull/12609#discussion_r2752492156


##########
doc/admin-guide/files/storage.yaml.en.rst:
##########
@@ -0,0 +1,495 @@
+.. Licensed to the Apache Software Foundation (ASF) under one
+   or more contributor license agreements.  See the NOTICE file
+   distributed with this work for additional information
+   regarding copyright ownership.  The ASF licenses this file
+   to you under the Apache License, Version 2.0 (the
+   "License"); you may not use this file except in compliance
+   with the License.  You may obtain a copy of the License at
+
+   http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing,
+   software distributed under the License is distributed on an
+   "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+   KIND, either express or implied.  See the License for the
+   specific language governing permissions and limitations
+   under the License.
+
+.. include:: ../../common.defs
+
+==============
+storage.yaml
+==============
+
+.. configfile:: storage.yaml
+
+The :file:`storage.yaml` file (by default, located in
+``/usr/local/etc/trafficserver/``) lists all the files, directories, and/or
+hard disk partitions that make up the Traffic Server cache. After you
+modify the :file:`storage.yaml` file the new settings will not be effective 
until Traffic Server is restarted.
+
+Format
+======
+
+The format of the :file:`storage.yaml` file is a series of lines of the form
+
+.. code-block:: yaml
+
+   cache:           # file level key
+     spans:         #
+       - name:      # name of the span
+         path:      # path to storage
+         size:      # size in bytes, required for file system storage, 
optional for raw device
+         hash_seed: # optional, used to isolate lookup from path changes
+     volumes:       # optional
+       - id:        # identifier [1-255]
+         size:      # optional, size in bytes or percentage
+         scheme:    # optional, default to "http"
+         ram_cache: # optional, default to "true"
+         spans:     # optional
+           - use:   # Span identifier
+             size:  # size allocated to this volume
+
+:code:`spans` lists the raw storage used for the cache. :code:`volumes` 
organizes the storage into locations for
+storing cached objects. This is very similar to operating system partitions 
and file systems.
+
+For :code:`spans` the keys are
+
++---------------+-------------+-------------------------------------------------------------+
+| Key           | Type        | Meaning                                        
             |
++===============+=============+=============================================================+
+| name          | string      | Name of the span.                              
             |
++---------------+-------------+-------------------------------------------------------------+
+| path          | string      | File system of the storage. This must be a 
block device or  |
+|               |             | directory.                                     
             |
++---------------+-------------+-------------------------------------------------------------+
+| size          | bytes       | Size in bytes. This is optional for devices 
but required    |
+|               |             | for directories.                               
             |
++---------------+-------------+-------------------------------------------------------------+
+| hash_seed     | string      | Hashing for object location uses a seed to 
randomize the    |
+|               |             | hash. By default this is the path for the 
span.             |
++---------------+-------------+-------------------------------------------------------------+
+
+For :code:`volumes` the keys are
+
++---------------+-------------+---------------------------------------------------------------------------------------------------------+
+| Key           | Type        | Meaning                                        
                                                         |
++===============+=============+=========================================================================================================+
+| id            | integer     | Id of the volume. Range is [1-255]. This id 
can be referred                                             |
+|               |             | from  :file:`hosting.config`                   
                                                         |

Review Comment:
   The phrase "This id can be referred from :file:`hosting.config`" is 
ungrammatical; it should be phrased as something like "This id can be referred 
to from :file:`hosting.config`" or "This id can be referenced from 
:file:`hosting.config`" for clarity.
   ```suggestion
   | id            | integer     | Id of the volume. Range is [1-255]. This id 
can be referred to                                          |
   |               |             | from :file:`hosting.config`                  
                                                           |
   ```



##########
doc/admin-guide/files/storage.yaml.en.rst:
##########
@@ -0,0 +1,495 @@
+.. Licensed to the Apache Software Foundation (ASF) under one
+   or more contributor license agreements.  See the NOTICE file
+   distributed with this work for additional information
+   regarding copyright ownership.  The ASF licenses this file
+   to you under the Apache License, Version 2.0 (the
+   "License"); you may not use this file except in compliance
+   with the License.  You may obtain a copy of the License at
+
+   http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing,
+   software distributed under the License is distributed on an
+   "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+   KIND, either express or implied.  See the License for the
+   specific language governing permissions and limitations
+   under the License.
+
+.. include:: ../../common.defs
+
+==============
+storage.yaml
+==============
+
+.. configfile:: storage.yaml
+
+The :file:`storage.yaml` file (by default, located in
+``/usr/local/etc/trafficserver/``) lists all the files, directories, and/or
+hard disk partitions that make up the Traffic Server cache. After you
+modify the :file:`storage.yaml` file the new settings will not be effective 
until Traffic Server is restarted.
+
+Format
+======
+
+The format of the :file:`storage.yaml` file is a series of lines of the form
+
+.. code-block:: yaml
+
+   cache:           # file level key
+     spans:         #
+       - name:      # name of the span
+         path:      # path to storage
+         size:      # size in bytes, required for file system storage, 
optional for raw device
+         hash_seed: # optional, used to isolate lookup from path changes
+     volumes:       # optional
+       - id:        # identifier [1-255]
+         size:      # optional, size in bytes or percentage
+         scheme:    # optional, default to "http"
+         ram_cache: # optional, default to "true"
+         spans:     # optional
+           - use:   # Span identifier
+             size:  # size allocated to this volume
+
+:code:`spans` lists the raw storage used for the cache. :code:`volumes` 
organizes the storage into locations for
+storing cached objects. This is very similar to operating system partitions 
and file systems.
+
+For :code:`spans` the keys are
+
++---------------+-------------+-------------------------------------------------------------+
+| Key           | Type        | Meaning                                        
             |
++===============+=============+=============================================================+
+| name          | string      | Name of the span.                              
             |
++---------------+-------------+-------------------------------------------------------------+
+| path          | string      | File system of the storage. This must be a 
block device or  |
+|               |             | directory.                                     
             |
++---------------+-------------+-------------------------------------------------------------+
+| size          | bytes       | Size in bytes. This is optional for devices 
but required    |
+|               |             | for directories.                               
             |
++---------------+-------------+-------------------------------------------------------------+
+| hash_seed     | string      | Hashing for object location uses a seed to 
randomize the    |
+|               |             | hash. By default this is the path for the 
span.             |
++---------------+-------------+-------------------------------------------------------------+
+
+For :code:`volumes` the keys are
+
++---------------+-------------+---------------------------------------------------------------------------------------------------------+
+| Key           | Type        | Meaning                                        
                                                         |
++===============+=============+=========================================================================================================+
+| id            | integer     | Id of the volume. Range is [1-255]. This id 
can be referred                                             |
+|               |             | from  :file:`hosting.config`                   
                                                         |
++---------------+-------------+---------------------------------------------------------------------------------------------------------+
+| size          | bytes       | Target size of the entire volume. This can be 
an absolute                                               |
+|               | _or_        | number of bytes or a percentage.               
                                                         |
+|               | percentage  |                                                
                                                         |
++---------------+-------------+---------------------------------------------------------------------------------------------------------+
+| scheme        | enumeration | Protocol scheme, defaults to "http". Preserved 
for future                                               |
+|               | string      | use.                                           
                                                         |
++---------------+-------------+---------------------------------------------------------------------------------------------------------+
+| ram_cache     | boolean     | Control of ram caching for this volume. 
Default is ``true``. This may be desirable if you are using     |
+|               |             | something like ramdisks, to avoid wasting RAM 
and CPU time on double caching objects.                   |
++---------------+-------------+---------------------------------------------------------------------------------------------------------+
+| avg_obj_size  | integer     | Overrides the global 
:ts:cv:`proxy.config.cache.min_average_object_size` configuration for this 
volume. |
+|               |             | This is useful if you have a volume that is 
dedicated for say very small objects, and you need a lot of |
+|               |             | directory entries to store them.               
                                                         |
++---------------+-------------+---------------------------------------------------------------------------------------------------------+
+| fragment_size | integer     | Overrides the global 
:ts:cv:`proxy.config.cache.target_fragment_size` configuration for this volume. 
   |
+|               |             | This allows for a smaller, or larger, fragment 
size for a particular volume. This may be useful         |
+|               |             | together with ``avg_obj_size`` as well, since 
a larger fragment size could reduce the number of         |
+|               |             | directory entries needed for a large object.   
                                                         |
++---------------+-------------+---------------------------------------------------------------------------------------------------------+
+| spans         | list        | Spans that provide storage for this volume. 
Defaults to                                                 |
+|               |             | all spans.                                     
                                                         |
++---------------+-------------+---------------------------------------------------------------------------------------------------------+
+
+For :code:`volumes:spans` the keys are
+
++---------------+-------------+-------------------------------------------------------------+
+| Key           | Type        | Meaning                                        
             |
++===============+=============+=============================================================+
+| use           | string      | Name of the span to use.                       
             |
++---------------+-------------+-------------------------------------------------------------+
+| size          | bytes       | Amount of the span to use. The total across 
all uses of     |
+|               | _or_        | this specific span must be less than 100% and 
less than the |
+|               | percentage  | total size of the span.                        
             |
++---------------+-------------+-------------------------------------------------------------+
+
+.. important::
+
+   Any change to this file can (and almost always will) invalidate the 
existing cache in its entirety.
+
+You can use any partition of any size. For best performance:
+
+-  Use raw disk partitions.
+-  For each disk, make all partitions the same size.
+-  Group similar kinds of storage into different volumes. For example
+   split out SSD's or RAM drives into their own volume.
+
+Specify pathnames according to your operating system requirements. See
+the following examples. In the :file:`storage.yaml` file, a formatted or
+raw disk must be at least 128 MB.
+
+When using raw disk or partitions, you should make sure the :ts:cv:`Traffic
+Server user <proxy.config.admin.user_id>` used by the Traffic Server process
+has read and write privileges on the raw disk device or partition. One good
+practice is to make sure the device file is set with 'g+rw' and the Traffic
+Server user is in the group which owns the device file.  However, some
+operating systems have stronger requirements - see the following examples for
+more information.
+
+As with standard ``records.yaml`` integers, human readable prefixes are also
+supported. They include
+
+   - ``K`` Kilobytes (1024 bytes)
+   - ``M`` Megabytes (1024^2 or 1,048,576 bytes)
+   - ``G`` Gigabytes (1024^3 or 1,073,741,824 bytes)
+   - ``T`` Terabytes (1024^4 or 1,099,511,627,776 bytes)
+
+Storage Allocation
+------------------
+
+Allocation of span storage to volumes is done in stages. Storage is always 
allocated in multiples of 128 megabytes,
+rounded down.
+
+*  Explicitly sized span storage (:code:`cache:volumes:spans:size`) is 
allocated to volumes. It is an error if the total allocated is larger than the 
span size.
+   *  Absolute sizes are allocated first.
+   *  Percentages are allocated from remaining space.
+   *  Remaining storage from spans that are used without an explicit size is 
divided evenly among the volumes that use the span.
+*  Span storage is allocated to volumes by the :code:`cache:volumes::size` 
values.

Review Comment:
   In the allocation description, the key path is documented as 
`cache:volumes::size` with a double colon, which is inconsistent with the 
earlier `cache:volumes:spans:size` notation and likely a typo; this should be 
updated to use a single colon before `size` (e.g. `cache:volumes:size`) to 
avoid confusing readers.
   ```suggestion
   *  Span storage is allocated to volumes by the :code:`cache:volumes:size` 
values.
   ```



##########
doc/admin-guide/files/storage.yaml.en.rst:
##########
@@ -0,0 +1,495 @@
+.. Licensed to the Apache Software Foundation (ASF) under one
+   or more contributor license agreements.  See the NOTICE file
+   distributed with this work for additional information
+   regarding copyright ownership.  The ASF licenses this file
+   to you under the Apache License, Version 2.0 (the
+   "License"); you may not use this file except in compliance
+   with the License.  You may obtain a copy of the License at
+
+   http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing,
+   software distributed under the License is distributed on an
+   "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+   KIND, either express or implied.  See the License for the
+   specific language governing permissions and limitations
+   under the License.
+
+.. include:: ../../common.defs
+
+==============
+storage.yaml
+==============
+
+.. configfile:: storage.yaml
+
+The :file:`storage.yaml` file (by default, located in
+``/usr/local/etc/trafficserver/``) lists all the files, directories, and/or
+hard disk partitions that make up the Traffic Server cache. After you
+modify the :file:`storage.yaml` file the new settings will not be effective 
until Traffic Server is restarted.
+
+Format
+======
+
+The format of the :file:`storage.yaml` file is a series of lines of the form
+
+.. code-block:: yaml
+
+   cache:           # file level key
+     spans:         #
+       - name:      # name of the span
+         path:      # path to storage
+         size:      # size in bytes, required for file system storage, 
optional for raw device
+         hash_seed: # optional, used to isolate lookup from path changes
+     volumes:       # optional
+       - id:        # identifier [1-255]
+         size:      # optional, size in bytes or percentage
+         scheme:    # optional, default to "http"
+         ram_cache: # optional, default to "true"
+         spans:     # optional
+           - use:   # Span identifier
+             size:  # size allocated to this volume
+
+:code:`spans` lists the raw storage used for the cache. :code:`volumes` 
organizes the storage into locations for
+storing cached objects. This is very similar to operating system partitions 
and file systems.
+
+For :code:`spans` the keys are
+
++---------------+-------------+-------------------------------------------------------------+
+| Key           | Type        | Meaning                                        
             |
++===============+=============+=============================================================+
+| name          | string      | Name of the span.                              
             |
++---------------+-------------+-------------------------------------------------------------+
+| path          | string      | File system of the storage. This must be a 
block device or  |
+|               |             | directory.                                     
             |
++---------------+-------------+-------------------------------------------------------------+
+| size          | bytes       | Size in bytes. This is optional for devices 
but required    |
+|               |             | for directories.                               
             |
++---------------+-------------+-------------------------------------------------------------+
+| hash_seed     | string      | Hashing for object location uses a seed to 
randomize the    |
+|               |             | hash. By default this is the path for the 
span.             |
++---------------+-------------+-------------------------------------------------------------+
+
+For :code:`volumes` the keys are
+
++---------------+-------------+---------------------------------------------------------------------------------------------------------+
+| Key           | Type        | Meaning                                        
                                                         |
++===============+=============+=========================================================================================================+
+| id            | integer     | Id of the volume. Range is [1-255]. This id 
can be referred                                             |
+|               |             | from  :file:`hosting.config`                   
                                                         |
++---------------+-------------+---------------------------------------------------------------------------------------------------------+
+| size          | bytes       | Target size of the entire volume. This can be 
an absolute                                               |
+|               | _or_        | number of bytes or a percentage.               
                                                         |
+|               | percentage  |                                                
                                                         |
++---------------+-------------+---------------------------------------------------------------------------------------------------------+
+| scheme        | enumeration | Protocol scheme, defaults to "http". Preserved 
for future                                               |
+|               | string      | use.                                           
                                                         |
++---------------+-------------+---------------------------------------------------------------------------------------------------------+
+| ram_cache     | boolean     | Control of ram caching for this volume. 
Default is ``true``. This may be desirable if you are using     |
+|               |             | something like ramdisks, to avoid wasting RAM 
and CPU time on double caching objects.                   |
++---------------+-------------+---------------------------------------------------------------------------------------------------------+
+| avg_obj_size  | integer     | Overrides the global 
:ts:cv:`proxy.config.cache.min_average_object_size` configuration for this 
volume. |
+|               |             | This is useful if you have a volume that is 
dedicated for say very small objects, and you need a lot of |
+|               |             | directory entries to store them.               
                                                         |
++---------------+-------------+---------------------------------------------------------------------------------------------------------+
+| fragment_size | integer     | Overrides the global 
:ts:cv:`proxy.config.cache.target_fragment_size` configuration for this volume. 
   |
+|               |             | This allows for a smaller, or larger, fragment 
size for a particular volume. This may be useful         |
+|               |             | together with ``avg_obj_size`` as well, since 
a larger fragment size could reduce the number of         |
+|               |             | directory entries needed for a large object.   
                                                         |
++---------------+-------------+---------------------------------------------------------------------------------------------------------+
+| spans         | list        | Spans that provide storage for this volume. 
Defaults to                                                 |
+|               |             | all spans.                                     
                                                         |
++---------------+-------------+---------------------------------------------------------------------------------------------------------+
+
+For :code:`volumes:spans` the keys are
+
++---------------+-------------+-------------------------------------------------------------+
+| Key           | Type        | Meaning                                        
             |
++===============+=============+=============================================================+
+| use           | string      | Name of the span to use.                       
             |
++---------------+-------------+-------------------------------------------------------------+
+| size          | bytes       | Amount of the span to use. The total across 
all uses of     |
+|               | _or_        | this specific span must be less than 100% and 
less than the |
+|               | percentage  | total size of the span.                        
             |
++---------------+-------------+-------------------------------------------------------------+
+
+.. important::
+
+   Any change to this file can (and almost always will) invalidate the 
existing cache in its entirety.
+
+You can use any partition of any size. For best performance:
+
+-  Use raw disk partitions.
+-  For each disk, make all partitions the same size.
+-  Group similar kinds of storage into different volumes. For example
+   split out SSD's or RAM drives into their own volume.
+
+Specify pathnames according to your operating system requirements. See
+the following examples. In the :file:`storage.yaml` file, a formatted or
+raw disk must be at least 128 MB.
+
+When using raw disk or partitions, you should make sure the :ts:cv:`Traffic
+Server user <proxy.config.admin.user_id>` used by the Traffic Server process
+has read and write privileges on the raw disk device or partition. One good
+practice is to make sure the device file is set with 'g+rw' and the Traffic
+Server user is in the group which owns the device file.  However, some
+operating systems have stronger requirements - see the following examples for
+more information.
+
+As with standard ``records.yaml`` integers, human readable prefixes are also
+supported. They include
+
+   - ``K`` Kilobytes (1024 bytes)
+   - ``M`` Megabytes (1024^2 or 1,048,576 bytes)
+   - ``G`` Gigabytes (1024^3 or 1,073,741,824 bytes)
+   - ``T`` Terabytes (1024^4 or 1,099,511,627,776 bytes)
+
+Storage Allocation
+------------------
+
+Allocation of span storage to volumes is done in stages. Storage is always 
allocated in multiples of 128 megabytes,
+rounded down.
+
+*  Explicitly sized span storage (:code:`cache:volumes:spans:size`) is 
allocated to volumes. It is an error if the total allocated is larger than the 
span size.
+   *  Absolute sizes are allocated first.
+   *  Percentages are allocated from remaining space.
+   *  Remaining storage from spans that are used without an explicit size is 
divided evenly among the volumes that use the span.
+*  Span storage is allocated to volumes by the :code:`cache:volumes::size` 
values.
+   *  Absolute sizes are allocated first.
+   *  Percentages are applied to remaining space.
+   *  Remaining storage is divided evenly among volumes without an explicit 
size.
+
+.. _storage-assignment-table:
+
+Assignment Table
+----------------
+
+Each storage element defined in :file:`storage.yaml` is divided into 
:term:`stripes <cache stripe>`. The
+assignment table maps from an object URL to a specific stripe. The table is 
initialized based on a
+pseudo-random process which is seeded by hashing a string for each stripe. 
This string is composed
+of a base string, an offset (the start of the stripe on the storage element), 
and the length of the
+stripe. By default the path for the storage is used as the base string. This 
ensures that each
+stripe has a unique string for the assignment hash. This does make the 
assignment table very
+sensitive to the path for the storage elements and changing even one can have 
a cascading effect
+which will effectively clear most of the cache. This can be a problem when 
drives fail and a system
+reboot causes the path names to change.
+
+The :arg:`name` option can be used to create a fixed string that an 
administrator can use to keep the
+assignment table consistent by maintaining the mapping from physical device to 
base string even in the presence of hardware changes and failures.
+
+Backwards Compatibility
+-----------------------
+
+In previous versions of |TS| it was possible to have "exclusive" spans which 
were used by only one volume. This is
+now done by specifying the span in the volume and using a size of "100%". E.g. 
old configuration like ::
+
+   /dev/disk2 volume=3 # storage.config
+   volume=3 scheme=http size=512 # volume.config
+
+The corresponding configuration would be
+
+.. code-block:: yaml
+
+   cache:
+     spans:
+       - name: disk.2
+         path: /dev/disk2
+     volumes:
+       - id: 1
+         spans:
+           - use: disk.2
+             size: 100%
+
+Because volume sizes that are percentages are computed on span storage not 
already explicitly allocated, this will
+leave none of "disk.2" for such allocation and therefore "disk.2" will be used 
only by volume "1". Note this
+configuration is more flexible. If it was useful to have two linear volumes, 
each using exclusively half of the
+span, this would be
+
+.. code-block:: yaml
+
+   cache:
+     spans:
+       - name: disk.2
+         path: /dev/disk2
+     volumes:
+       - id: 1
+         spans:
+           - use: disk.2
+             size: 50%
+       - id: 2
+         spans:
+           - use: disk.2
+             size: 50%
+
+.. important::
+
+   If a span is explicitly used by any volume its storage will be allocated to 
only volumes that explicitly use that span.
+
+Examples
+========
+
+The following basic example shows 128 MB of cache storage in the "/big_dir" 
directory
+
+.. code-block:: yaml
+
+   cache:
+     spans:
+       - name: store
+         path: /big_dir
+         size: 134217728
+
+By default a volume uses all spans, therefore a volume uses all of span 
"store" because there are no other
+volumes. It would be equivalent to using the spans explicitly, e.g.
+
+.. code-block:: yaml
+
+   cache:
+     spans:
+       - name: store
+         path: /big_dir
+         size: 134217728
+     volumes:
+       - id: 1
+         size: 100%
+         spans:
+           - use: store
+
+You can use the ``.`` symbol for the current directory. Here is an example for 
128 MB of cache storage in the current directory
+
+.. code-block:: yaml
+
+   cache:
+     spans:
+       - name: store
+         path: "."
+         size: 134217728
+
+.. note::
+    When using on-filesystem cache disk storage, you can only have one such
+    directory specified. This will be addressed in a future version.
+
+Linux Example
+-------------
+.. note::
+
+   Rather than refer to disk devices like ``/dev/sda``, ``/dev/sdb``, etc.,
+   modern Linux supports `alternative symlinked names for disk devices
+   
<https://wiki.archlinux.org/index.php/persistent_block_device_naming#by-id_and_by-path>`_
 in the ``/dev/disk``
+   directory structure. As noted for the :ref:`storage-assignment-table` the 
path used for the disk can affect
+   the cache if it changes. This can be ameliorated in some cases by using one 
of the alternate paths
+   in via ``/dev/disk``. Note that if the ``by-id`` or ``by-path`` style is 
used, replacing a failed drive will cause
+   that path to change because the new drive will have a different physical ID 
or path.
+
+   If this is not sufficient then the :arg:`hash_seed` key should be used to 
create a more permanent
+   assignment table. An example would be
+
+   .. code-block:: yaml
+
+      cache:
+        spans:
+          - name: "span.0"
+            path: "/dev/sde"
+            hash_seed: "cache.disk.0"
+          - name: "span.1"
+            path: "/dev/sdg"
+            hash_seed: "cache.disk.1"
+
+The following example will use an entire raw disk in the Linux operating
+system
+
+.. code-block:: yaml
+
+   cache:
+     spans:
+       - name: a
+         path: "/dev/disk/by-id/disk-A-id"
+       - name: b
+         path: "/dev/disk/by-id/disk-B-id"
+     volumes:
+       - id: 1
+         spans:
+           - use: a
+             size: 100%
+       - id: 2
+         spans:
+           - use: b
+             size: 100%
+
+In order to make sure :program:`traffic_server` will have access to this disk
+you can use :manpage:`udev(7)` to persistently set the right permissions. The
+following rules are targeted for an Ubuntu system, and stored in
+``/etc/udev/rules.d/51-cache-disk.rules``::
+
+   # Assign DiskA and DiskB to the tserver group
+   # make the assignment final, no later changes allowed to the group!
+   SUBSYSTEM=="block", KERNEL=="sd[ef]", GROUP:="tserver"
+
+In order to apply these settings, trigger a reload with :manpage:`udevadm(8)`::
+
+   udevadm trigger --subsystem-match=block
+
+
+FreeBSD Example
+---------------
+
+Starting with 5.1 FreeBSD dropped support for explicit raw devices. All
+devices on FreeBSD can be accessed raw now.
+
+The following example will use an entire raw disk in the FreeBSD
+operating system
+
+.. code-block:: yaml
+
+   cache:
+     spans:
+       - name: ada.1
+         path: "/dev/ada1"
+       - name: ada.2
+         path: "/dev/ada2"
+     volumes:
+       - id: 1
+         size: 100%
+
+In order to make sure :program:`traffic_server` will have access to this disk
+you can use :manpage:`devfs(8)` to persistently set the right permissions. The
+following rules are stored in :manpage:`devfs.conf(5)`::
+
+   # Assign /dev/ada1 and /dev/ada2 to the tserver user
+   own    ada[12]  tserver:tserver
+
+Advanced
+--------
+
+Because relative paths in :file:`storage.yaml` are relative to the base 
prefix, when using customized runroot
+it may be necessary to adjust such paths in :file:`storage.yaml` or adjust 
``runroot.yaml`` itself.
+Despite the name, the cachedir value is not used for this file.
+
+Examples
+========
+
+The following example partitions the cache across 5 volumes to decrease 
single-lock pressure for a
+machine with few drives. The last volume being an example of one that might be 
composed of purely
+ramdisks so that the ram cache has been disabled.
+
+.. code-block:: yaml
+
+   cache:
+     spans:
+       - name: disk
+         path: "/dev/sdb"
+     volumes:
+       - id: 1
+         size: 20%
+       - id: 2
+         size: 20%
+       - id: 3
+         size: 20%
+       - id: 4
+         size: 20%
+         avg_obj_size: 4096
+       - id: 5
+         size: 20%
+         ram_cache: false
+
+This can be simplified by depending on the default allocation which splits 
unallocated span storage across volumes.
+
+.. code-block:: yaml
+
+   cache:
+     spans:
+       - name: disk
+         path: "/dev/sdb"
+     volumes:
+       - id: 1
+       - id: 2
+       - id: 3
+       - id: 4
+       - id: 5
+         ram_cache: false
+
+For a host with a physical disk and two ram disks, where the ram disks should 
be split between two volumes, with a third
+volume that uses the physical disk.
+
+This depends on defaults. The spans "ram.1" and "ram.2" are split evenly 
between volume "1" and volume "2" because no
+sizes are specified. Span "disk" is not used for volume "1" nor volume "2" 
because it is not listed in the ``spans``.
+Volume "3" therefore gets all of span "disk".
+
+.. code-block:: yaml
+
+   cache:
+     spans:
+       - name: disk
+         path: "/dev/sdb"
+       - name: ram.1
+         path: "/dev/ram.1"
+       - name: ram.2
+         path: "/dev/ram.2"
+     volumes:
+       - id: 1
+         spans:
+           - use: ram.1
+           - use: ram.2
+       - id: 2
+         spans:
+           - use: ram.1
+           - use: ram.2
+       - id: 3
+
+If one of the ram disk based volumes should be larger, this could be done as 
follows by making volume "1" roughly twice
+as large as volume "2".
+
+.. code-block:: yaml
+
+   cache:
+      spans:
+      - name: disk
+        path: "/dev/sdb"
+      - name: ram.1
+        path: "/dev/ram.1"
+      - name: ram.2
+        path: "/dev/ram.2"
+      volumes:
+      - id: 1
+        spans:
+          - use: ram.1
+            size: 66%
+          - use: ram.2
+            size: 66%
+      - id: 2
+        spans:
+          - use: ram.1
+          - use: ram.2
+      - id: 3

Review Comment:
   The YAML example here is not syntactically valid because the list items 
under `spans` use the same indentation as the `spans` key; the `- name` lines 
should be indented further under `spans` (and similarly for the `volumes` list 
below) so that the example can be copy-pasted as valid YAML.
   ```suggestion
           - name: disk
             path: "/dev/sdb"
           - name: ram.1
             path: "/dev/ram.1"
           - name: ram.2
             path: "/dev/ram.2"
         volumes:
           - id: 1
             spans:
               - use: ram.1
                 size: 66%
               - use: ram.2
                 size: 66%
           - id: 2
             spans:
               - use: ram.1
               - use: ram.2
           - id: 3
   ```



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