[
https://issues.apache.org/jira/browse/HDFS-2802?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13658864#comment-13658864
]
Chris Nauroth commented on HDFS-2802:
-------------------------------------
Nicholas, I have not been able to get a successful run of this test in one of
my VMs by removing the timeout. I added logging to observe the test's progress
creating 2^16 snapshots. Projecting out, I estimate that it would take ~2.5
hours to complete in my VM. :-)
I traced the performance problem to the edit log flushes. I can fix the
problem by changing the test to call
{{EditLogFileOutputStream#setShouldSkipFsyncForTesting}}. I'll submit a patch
in a separate jira for this.
This is not a Windows problem. This is a slow virtualized disk problem across
all of my VirtualBox VMs. I also ran the test on one of my Ubuntu VMs and
observed similar performance. The performance is not a problem when I run it
on my Mac against physical disk.
> Support for RW/RO snapshots in HDFS
> -----------------------------------
>
> Key: HDFS-2802
> URL: https://issues.apache.org/jira/browse/HDFS-2802
> Project: Hadoop HDFS
> Issue Type: New Feature
> Components: datanode, namenode
> Reporter: Hari Mankude
> Assignee: Tsz Wo (Nicholas), SZE
> Attachments: 2802.diff, 2802.patch, 2802.patch, h2802_20130417.patch,
> h2802_20130422.patch, h2802_20130423.patch, h2802_20130425.patch,
> h2802_20130426.patch, h2802_20130430b.patch, h2802_20130430.patch,
> h2802_20130508.patch, h2802_20130509.patch, HDFS-2802.20121101.patch,
> HDFS-2802.branch-2.0510.patch, HDFS-2802-meeting-minutes-121101.txt,
> HDFSSnapshotsDesign.pdf, snap.patch, snapshot-design.pdf,
> snapshot-design.tex, snapshot-one-pager.pdf, Snapshots20120429.pdf,
> Snapshots20121018.pdf, Snapshots20121030.pdf, Snapshots.pdf,
> snapshot-testplan.pdf
>
>
> Snapshots are point in time images of parts of the filesystem or the entire
> filesystem. Snapshots can be a read-only or a read-write point in time copy
> of the filesystem. There are several use cases for snapshots in HDFS. I will
> post a detailed write-up soon with with more information.
--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators
For more information on JIRA, see: http://www.atlassian.com/software/jira
