Sahil Takiar created IMPALA-9224:
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Summary: Blacklist nodes with faulty disks
Key: IMPALA-9224
URL: https://issues.apache.org/jira/browse/IMPALA-9224
Project: IMPALA
Issue Type: Improvement
Components: Backend
Reporter: Sahil Takiar
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.
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