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https://issues.apache.org/jira/browse/KUDU-2260?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16516459#comment-16516459
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Will Berkeley commented on KUDU-2260:
-------------------------------------
One other important detail: the NULL byte guarantee holds when using the
default data=ordered guarantee or stronger. If ext4 is mounted with
data=writeback then we could find anything at the end. So we can
(transparently) recover from this situation at startup under default ext4
settings.
> Log block manager should handle null bytes in metadata on crash
> ---------------------------------------------------------------
>
> Key: KUDU-2260
> URL: https://issues.apache.org/jira/browse/KUDU-2260
> Project: Kudu
> Issue Type: Bug
> Components: fs
> Reporter: Mike Percy
> Priority: Major
>
> The log block manager currently may leave null bytes at the end of the
> metadata log file if there is a system crash in the middle of a write. The
> log block manager should detect null bytes at the end of a metadata entry on
> startup and potentially truncate the entry or close the container.
> Currently, it prints an error along the following lines:
> {code}
> F0111 09:30:27.327011 28843 tablet_server_main.cc:64] Check failed: _s.ok()
> Bad status: Corruption: Failed to load FS layout: Could not read records from
> container /data/3/kudu/data/f70391c7c6084e08bbae7448518e0b5e: Data length
> checksum does not match: Incorrect checksum in file
> /data/3/kudu/data/f70391c7c6084e08bbae7448518e0b5e.metadata at offset 372533:
> Checksum does not match. Expected: 0. Actual: 1323915147
> {code}
> At the time of writing, the workaround for this issue is to truncate the
> affected file at the start of the incomplete entry in the file. While this
> may leave orphaned blocks, this should be safe because if the metadata entry
> was never successfully written then it should not have been considered
> durable, either.
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