17390: Document arv:OutputStorageClass extension

[arvados.git] / doc / user / topics / storage-classes.html.textile.liquid

diff --git a/doc/user/topics/storage-classes.html.textile.liquid b/doc/user/topics/storage-classes.html.textile.liquid
index 96c808306272add476bcf428d481160d0562baec..06fd4d811c2b0e927f13e4fbb1af2c3f8395b386 100644 (file)
--- a/doc/user/topics/storage-classes.html.textile.liquid
+++ b/doc/user/topics/storage-classes.html.textile.liquid
@@ -10,27 +10,35 @@ Copyright (C) The Arvados Authors. All rights reserved.
 SPDX-License-Identifier: CC-BY-SA-3.0
 {% endcomment %}
 
-Storage classes (alternately known as "storage tiers") allow you to control which volumes should be used to store particular collection data blocks.  This can be used to implement data storage policies such as moving data to archival storage.
+Storage classes (sometimes called as "storage tiers") allow you to control which back-end storage volumes should be used to store the data blocks of a particular collection.  This can be used to implement data storage policies such as assigning data collections to "fast", "robust" or "archival" storage.
 
-Names of storage classes are internal to the cluster and decided by the administrator.  Aside from "default", Arvados currently does not define any standard storage class names.
+Names of storage classes are internal to the cluster and decided by the administrator.  Aside from "default", Arvados currently does not define any standard storage class names.  Consult your cluster administrator for guidance on what storage classes are available to use on your specific Arvados instance.
+
+Note that when changing the storage class of an existing collection, it does not take effect immediately, the blocks are asynchronously copied to the new storage class and removed from the old one.  The collection field "storage_classes_confirmed" is updated to reflect when data blocks have been successfully copied.
 
 h3. arv-put
 
-You may specify the desired storage class for a collection uploaded using @arv-put@:
+You may specify one or more desired storage classes for a collection uploaded using @arv-put@:
 
 <pre>
-$ arv-put --storage-classes=hot myfile.txt
+$ arv-put --storage-classes=hot,archival myfile.txt
 </pre>
 
-h3. arvados-cwl-runner
+h3. arv-mount
 
-You may also specify the desired storage class for the final output collection produced by @arvados-cwl-runner@:
+You can ask @arv-mount@ to use specific storage classes when creating new collections:
 
 <pre>
-$ arvados-cwl-runner --storage-classes=hot myworkflow.cwl myinput.yml
+$ arv-mount --storage-classes=transient --mount-tmp=scratch keep
 </pre>
 
-(Note: intermediate collections produced by a workflow run will have "default" storage class.)
+h3. arvados-cwl-runner
+
+You may specify the desired storage class for the intermediate and final output collections produced by @arvados-cwl-runner@ on the command line or using the "arv:OutputStorageClass hint":{{site.baseurl}}/user/cwl/cwl-extensions.html#OutputStorageClass .
+
+<pre>
+$ arvados-cwl-runner --intermediate-storage-classes=hot_storage --storage-classes=robust_storage myworkflow.cwl myinput.yml
+</pre>
 
 h3. arv command line
 
@@ -44,10 +52,6 @@ By setting "storage_classes_desired" to "archival", the blocks that make up the
 
 h3. Storage class notes
 
-Collection blocks will be in the "default" storage class if not otherwise specified.
-
-Currently, a collection may only have one desired storage class.
+Collection blocks will be in the cluster's configured default storage class(es) if not otherwise specified.
 
 Any user with write access to a collection may set any storage class on that collection.
-
-Names of storage classes are internal to the cluster and decided by the administrator.  Aside from "default", Arvados currently does not define any standard storage class names.