[jira] [Updated] (HDDS-17328) EC read waits about 2 minutes on an unresponsive datanode before switching to reconstruction

["Siyao Meng (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/HDDS-17328?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Siyao Meng updated HDDS-17328:
------------------------------
    Epic Link: HDDS-17321

> 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
>            Assignee: 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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