[jira] [Updated] (CASSANDRA-7872) ensure compacted obsolete sstables are not open on node restart and nodetool refresh, even on sstable reference miscounting or deletion tasks are failed.

["T Jake Luciani (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/CASSANDRA-7872?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

T Jake Luciani updated CASSANDRA-7872:
--------------------------------------
    Fix Version/s:     (was: 2.0.12)
                   2.0.13

> ensure compacted obsolete sstables are not open on node restart and nodetool refresh, even on sstable reference miscounting or deletion tasks are failed.
> ---------------------------------------------------------------------------------------------------------------------------------------------------------
>
>                 Key: CASSANDRA-7872
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-7872
>             Project: Cassandra
>          Issue Type: Bug
>          Components: Core
>            Reporter: Oleg Anastasyev
>            Assignee: Oleg Anastasyev
>             Fix For: 2.0.13
>
>         Attachments: 7872-v2.0-NoPhQ.txt, 7872-v2.0-bugdetector.txt, 7872-v2.0-robustness.txt, EnsureNoObsoleteSSTables-7872-v2.0.txt
>
>
> Since CASSANDRA-4436 compacted sstables are no more marked with COMPACTED_MARKER file. Instead after they are compacted, DataTracker calls SSTableReader.markObsolete(), but the actual deletion is happening later on SSTableReader.releaseReference().
> This reference counting is very fragile, it is very easy to introduce a hard-to-catch and rare bug, so this reference count never reaches 0 ( like CASSANDRA-6503 for example )
> This means, that very rarely obsolete sstable files are not removed from disk (but are not used anymore by cassandra to read data).
> If more than gc grace time has passed since sstable file was not removed from disk and operator issues either nodetool refresh or just reboots a node, these obsolete files are being discovered and open for read by a node. So deleted data is resurrected, being quickly spread by RR to whole cluster.
> Because consequences are very serious (even a single not removed obsolete sstable file could render your data useless) this patch makes sure no obsolete sstable file can be open for read by:
> 1. Removing sstables on CFS init analyzing sstable generations (sstable is removed, if there are another sstable, listing this as ancestor)
> 2. Reimplementing COMPACTED_MARKER file for sstable. This marker is created as soon as markObsolete is called. This is neccessary b/c generation info can be lost (when sstables compact to none)
> 3. To remove sstables sooner then restart - reimplemented the good old GC phantom reference queue as well. 



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