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https://issues.apache.org/jira/browse/HDDS-17328?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Siyao Meng reassigned HDDS-17328:
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Assignee: (was: Siyao Meng)
> EC read waits about 2 minutes on an unresponsive datanode before switching to
> reconstruction
> --------------------------------------------------------------------------------------------
>
> Key: HDDS-17328
> URL: https://issues.apache.org/jira/browse/HDDS-17328
> Project: Apache Ozone
> Issue Type: Improvement
> Components: EC Client
> Reporter: Siyao Meng
> Priority: Major
>
> {{ECBlockInputStream}} reads each data index through a single-datanode
> pipeline. On a failed read, its {{BlockInputStream}} retries
> {{ozone.client.read.max.retries}} (3) times with
> {{ozone.client.read.retry.interval}} (1s), and a deadline exceeded error is
> not treated as a connectivity failure, so it retries the same datanode. Only
> then does {{BadDataLocationException}} make {{ECBlockInputStreamProxy}}
> switch to reconstruction read. With an unresponsive datanode (not refusing
> connections) this is 4 × 30s ({{ozone.client.read.timeout}}) + 3 × 1s, about
> 2 minutes, for each block with an index on that datanode (by calculation). A
> datanode that refuses connections fails in a few seconds.
> Proposed fix: switch to reconstruction read on the first timeout from a
> datanode, instead of retrying the same datanode.
> Related: HDDS-16871 (share failed datanodes across the blocks of a key),
> HDDS-16868
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