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https://issues.apache.org/jira/browse/HDFS-7584?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14287990#comment-14287990
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Zhe Zhang commented on HDFS-7584:
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bq. "the cumulative disk space quota" in the spec means traditional space quota
not quota of DISK type
Thanks for clarifying. Then section 5.1 is a pure intended-usage based policy,
and makes more sense now. But then how should we coordinate type-based quotas
and the "traditional space quota"? Is the latter the summation of quotas from
all types? If I set my SSD quota as 1GB and DISK quota as 2GB, do I need to
separately set my overall space quota to be 3GB?
bq. If the fallback still can't be satisfied due to DISK quota unavailable, the
user will get QuotaByStorageTypeExceeded exception.
This is where it would be helpful to exchange type quotas. Revising the example
a little bit, let's assume I have 3 blocks of SSD quota and no DISK quota, and
the cluster has no SSD storage and plenty of DISK storage. When trying to
create a 1 block file with replication factor of 3, under ONE_SSD policy, the
user would expect a success because he has 3 blocks of quota in the most
expensive type. I understand setting "exchange rates" needs more discussion.
Can we at least allow more expensive quotas to be used on less expensive
storages?
> Enable Quota Support for Storage Types (SSD)
> ---------------------------------------------
>
> Key: HDFS-7584
> URL: https://issues.apache.org/jira/browse/HDFS-7584
> Project: Hadoop HDFS
> Issue Type: New Feature
> Components: datanode, namenode
> Reporter: Xiaoyu Yao
> Assignee: Xiaoyu Yao
> Attachments: HDFS-7584 Quota by Storage Type - 01202015.pdf,
> HDFS-7584.0.patch
>
>
> Phase II of the Heterogeneous storage features have completed by HDFS-6584.
> This JIRA is opened to enable Quota support of different storage types in
> terms of storage space usage. This is more important for certain storage
> types such as SSD as it is precious and more performant.
> As described in the design doc of HDFS-5682, we plan to add new
> quotaByStorageType command and new name node RPC protocol for it. The quota
> by storage type feature is applied to HDFS directory level similar to
> traditional HDFS space quota.
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