Details
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Sub-task
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Status: Resolved
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Critical
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Resolution: Fixed
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None
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None
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ghx-label-12
Description
Similar to IMPALA-8339 and IMPALA-9137, Impala should blacklist nodes with faulty disks. Specifically, if a query fails because of a disk error, the node with that disk should be blacklisted and the query should be retried.
We shouldn't need to blacklist nodes that fail to read from HDFS / S3, since they contain their own internal mechanisms for recovering from faulty disks. We should only blacklist nodes when failing to read / write from local disks.
The two main components of Impala that read / write from local disk are the spill-to-disk and data caching features. Whenever a query fails because of a disk failure during spill-to-disk, the node should be blacklisted.
Reads / writes from / to the data cache are a bit different. If a cache read fails due to a disk error, the error will be printed out and the Lookup() call to the cache will return 0 bytes read, which means it couldn't find the data in the cache. This should cause the scan to fall back to a normal, un-cached read. While this doesn't affect query correctness or the ability for a query to complete, it can affect performance. Since cache failures don't result in query failures, we might consider having a threshold of data cache read / writes errors before blacklisting a node.
We need to be careful to only capture specific disk failures - e.g. disk quota, permission denied, etc. errors shouldn't result in blacklisting as they typically are a result of system misconfiguration.
Attachments
Issue Links
- is related to
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- Resolved
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- Resolved
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- relates to
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IMPALA-4683 Intelligently blacklist scratch disks with physical I/O errors
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- Open
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