[
https://issues.apache.org/jira/browse/HADOOP-10809?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Eric Hanson updated HADOOP-10809:
---------------------------------
Attachment: HADOOP-10809.05.patch
Backing up work in progress. Finished merge of all files and did basic
verification in eclipse to make sure all the names resolve. Still need to
compile and run Azure filesystem unit tests.
> hadoop-azure: page blob support
> -------------------------------
>
> Key: HADOOP-10809
> URL: https://issues.apache.org/jira/browse/HADOOP-10809
> Project: Hadoop Common
> Issue Type: Improvement
> Components: tools
> Reporter: Mike Liddell
> Assignee: Eric Hanson
> Attachments: HADOOP-10809.02.patch, HADOOP-10809.03.patch,
> HADOOP-10809.04.patch, HADOOP-10809.05.patch, HADOOP-10809.1.patch
>
>
> Azure Blob Storage provides two flavors: block-blobs and page-blobs.
> Block-blobs are the general purpose kind that support convenient APIs and are
> the basis for the Azure Filesystem for Hadoop (see HADOOP-9629).
> Page-blobs use the same namespace as block-blobs but provide a different
> low-level feature set. Most importantly, page-blobs can cope with an
> effectively infinite number of small accesses whereas block-blobs can only
> tolerate 50K appends before relatively manual rewriting of the data is
> necessary. A simple analogy is that page-blobs are like a regular disk and
> the basic API is like a low-level device driver.
> See http://msdn.microsoft.com/en-us/library/azure/ee691964.aspx for some
> introductory material.
> The primary driving scenario for page-blob support is for HBase transaction
> log files which require an access pattern of many small writes. Additional
> scenarios can also be supported.
> Configuration:
> The Hadoop Filesystem abstraction needs a mechanism so that file-create can
> determine whether to create a block- or page-blob. To permit scenarios where
> application code doesn't know about the details of azure storage we would
> like the configuration to be Aspect-style, ie configured by the Administrator
> and transparent to the application. The current solution is to use hadoop
> configuration to declare a list of page-blob folders -- Azure Filesystem for
> Hadoop will create files in these folders using page-blob flavor. The
> configuration key is "fs.azure.page.blob.dir", and description can be found
> in AzureNativeFileSystemStore.java.
> Code changes:
> - refactor of basic Azure Filesystem code to use a general BlobWrapper and
> specialized BlockBlobWrapper vs PageBlobWrapper
> - introduction of PageBlob support (read, write, etc)
> - miscellaneous changes such as umask handling, implementation of
> createNonRecursive(), flush/hflush/hsync.
> - new unit tests.
> Credit for the primary patch: Dexter Bradshaw, Mostafa Elhemali, Eric Hanson,
> Mike Liddell.
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
