HDFS-8852. HDFS architecture documentation of version 2.x is outdated about append write support. Contributed by Ajith S.
Project: http://git-wip-us.apache.org/repos/asf/hadoop/repo Commit: http://git-wip-us.apache.org/repos/asf/hadoop/commit/fc509f66 Tree: http://git-wip-us.apache.org/repos/asf/hadoop/tree/fc509f66 Diff: http://git-wip-us.apache.org/repos/asf/hadoop/diff/fc509f66 Branch: refs/heads/YARN-1197 Commit: fc509f66d814e7a5ed81d5d73b23c400625d573b Parents: 71566e2 Author: Akira Ajisaka <[email protected]> Authored: Tue Aug 18 23:31:52 2015 +0900 Committer: Akira Ajisaka <[email protected]> Committed: Tue Aug 18 23:31:52 2015 +0900 ---------------------------------------------------------------------- hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt | 3 +++ hadoop-hdfs-project/hadoop-hdfs/src/site/markdown/HdfsDesign.md | 2 +- 2 files changed, 4 insertions(+), 1 deletion(-) ---------------------------------------------------------------------- http://git-wip-us.apache.org/repos/asf/hadoop/blob/fc509f66/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt ---------------------------------------------------------------------- diff --git a/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt b/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt index 132adc1..3a7b816 100644 --- a/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt +++ b/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt @@ -1191,6 +1191,9 @@ Release 2.7.2 - UNRELEASED HDFS-8806. Inconsistent metrics: number of missing blocks with replication factor 1 not properly cleared. (Zhe Zhang via aajisaka) + HDFS-8852. HDFS architecture documentation of version 2.x is outdated + about append write support. (Ajith S via aajisaka) + Release 2.7.1 - 2015-07-06 INCOMPATIBLE CHANGES http://git-wip-us.apache.org/repos/asf/hadoop/blob/fc509f66/hadoop-hdfs-project/hadoop-hdfs/src/site/markdown/HdfsDesign.md ---------------------------------------------------------------------- diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/site/markdown/HdfsDesign.md b/hadoop-hdfs-project/hadoop-hdfs/src/site/markdown/HdfsDesign.md index a30877a..aa94a2f 100644 --- a/hadoop-hdfs-project/hadoop-hdfs/src/site/markdown/HdfsDesign.md +++ b/hadoop-hdfs-project/hadoop-hdfs/src/site/markdown/HdfsDesign.md @@ -73,7 +73,7 @@ Applications that run on HDFS have large data sets. A typical file in HDFS is gi ### Simple Coherency Model -HDFS applications need a write-once-read-many access model for files. A file once created, written, and closed need not be changed. This assumption simplifies data coherency issues and enables high throughput data access. A Map/Reduce application or a web crawler application fits perfectly with this model. There is a plan to support appending-writes to files in the future. +HDFS applications need a write-once-read-many access model for files. A file once created, written, and closed need not be changed except for appends and truncates. Appending the content to the end of the files is supported but cannot be updated at arbitrary point. This assumption simplifies data coherency issues and enables high throughput data access. A MapReduce application or a web crawler application fits perfectly with this model. ### "Moving Computation is Cheaper than Moving Data"
