[jira] Commented: (HADOOP-3860) Compare name-node performance when journaling is performed into local hard-drives or nfs.

["dhruba borthakur (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HADOOP-3860?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12620141#action_12620141 ] 

dhruba borthakur commented on HADOOP-3860:
------------------------------------------

Hi Konstantin, 

Great analysis. I completely agree with you that coarse-grain locking for the namenode should not be impacting scalability of opens and creates. It is the disk sync times that really matters. BTW, when you ran the test on a single disk on local drive, did you see the disk max-out on IO? You said that 5710 creates occured, the limitation being CPU on the machine or disk IO contention?

Also, I had a patch HADOOP-2330 that pre-allocated transaction log. If I had seen this JIRA earlier, i would have requested you to see if you could repeat the exact same test on the same hardware with this patch. This patch pre-allocates the transaction log in large chunks.

> Compare name-node performance when journaling is performed into local hard-drives or nfs.
> -----------------------------------------------------------------------------------------
>
>                 Key: HADOOP-3860
>                 URL: https://issues.apache.org/jira/browse/HADOOP-3860
>             Project: Hadoop Core
>          Issue Type: Improvement
>    Affects Versions: 0.19.0
>            Reporter: Konstantin Shvachko
>            Assignee: Konstantin Shvachko
>             Fix For: 0.19.0
>
>         Attachments: NNThruputMoreOps.patch
>
>
> The goal of this issue is to measure how the name-node performance depends on where the edits log is written to.
> Three types of the journal storage should be evaluated:
> # local hard drive;
> # remote drive mounted via nfs;
> # nfs filer.

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