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https://issues.apache.org/jira/browse/HADOOP-13868?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16888382#comment-16888382
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Steve Loughran commented on HADOOP-13868:
-----------------------------------------
LGTM +1
> New defaults for S3A multi-part configuration
> ---------------------------------------------
>
> Key: HADOOP-13868
> URL: https://issues.apache.org/jira/browse/HADOOP-13868
> Project: Hadoop Common
> Issue Type: Bug
> Components: fs/s3
> Affects Versions: 2.7.0, 3.0.0-alpha1
> Reporter: Sean Mackrory
> Assignee: Sean Mackrory
> Priority: Major
> Attachments: HADOOP-13868.001.patch, HADOOP-13868.002.patch,
> optimizing-multipart-s3a.sh
>
>
> I've been looking at a big performance regression when writing to S3 from
> Spark that appears to have been introduced with HADOOP-12891.
> In the Amazon SDK, the default threshold for multi-part copies is 320x the
> threshold for multi-part uploads (and the block size is 20x bigger), so I
> don't think it's necessarily wise for us to have them be the same.
> I did some quick tests and it seems to me the sweet spot when multi-part
> copies start being faster is around 512MB. It wasn't as significant, but
> using 104857600 (Amazon's default) for the blocksize was also slightly better.
> I propose we do the following, although they're independent decisions:
> (1) Split the configuration. Ideally, I'd like to have
> fs.s3a.multipart.copy.threshold and fs.s3a.multipart.upload.threshold (and
> corresponding properties for the block size). But then there's the question
> of what to do with the existing fs.s3a.multipart.* properties. Deprecation?
> Leave it as a short-hand for configuring both (that's overridden by the more
> specific properties?).
> (2) Consider increasing the default values. In my tests, 256 MB seemed to be
> where multipart uploads came into their own, and 512 MB was where multipart
> copies started outperforming the alternative. Would be interested to hear
> what other people have seen.
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