[GitHub] [hadoop-ozone] arp7 commented on a change in pull request #1411: HDDS-4097. [DESIGN] S3/Ozone Filesystem inter-op

[GitBox <gi...@apache.org>]

arp7 commented on a change in pull request #1411:
URL: https://github.com/apache/hadoop-ozone/pull/1411#discussion_r485693614



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File path: hadoop-hdds/docs/content/design/s3_hcfs.md
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@@ -67,45 +66,100 @@ To solve the performance problems of the directory listing / rename, [HDDS-2939]
 
 [HDDS-4097](https://issues.apache.org/jira/browse/HDDS-4097) is created to normalize the key names based on file-system semantics if `ozone.om.enable.filesystem.paths` is enabled. But please note that `ozone.om.enable.filesystem.paths` should always be turned on if S3 and HCFS are both used which means that S3 and HCFS couldn't be used together with normalization.
 
-## Goals
+# Goals
+
+ * Out of the box Ozone should support both S3 and HCFS interfaces without any settings. (It's possible only for the regular, fs compatible key names)
+ * As 100% compatibility couldn't be achieved on both side we need a configuration to set the expectations for incompatible key names
+ * Default behavior of `o3fs` and `ofs` should be as close to `s3a` as possible (when s3 compatibilty is prefered)
+
+# Possible cases to support
+
+There are two main aspects of supporting both `ofs/o3fs` and `s3` together:
+
+ 1. `ofs/o3fs` require to create intermediate directory entries (for exapmle `/a/b` for the key `/b/c/c`)
+ 2. Special file-system incompatible key names require special attention
+
+The second couldn't be done with compromise.
+
+ 1. We either support all key names (including non fs compatible key names), which means `ofs/o3fs` can provide only a partial view
+ 2. Or we can normalize the key names to be fs compatible (which makes it possible to create inconsistent S3 keys)
+
+HDDS-3955 introduced `ozone.om.enable.filesystem.paths`, with this setting we will have two possible usage pattern:
+
+| ozone.om.enable.filesystem.paths= | true | false
+|-|-|-|
+| create itermediate dirs | YES | NO |
+| normalize key names from `ofs/o3fs` | YES | NO
+| force to normalize key names of `s3` interface | YES (1) | NO 
+| `s3` key `/a/b/c` available from `ofs/o3fs` | YES | NO
+| `s3` key `/a/b//c` available from `ofs/o3fs` | YES | NO
+| `s3` key `/a/b//c` available from `s3` | AWS S3 incompatibility | YES
+
+(1): Under implementation

Review comment:
       I don't think that is true. Paths are normalized already on the S3 interface when writing new keys.




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