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From Elias Levy <fearsome.lucid...@gmail.com>
Subject Re: RocksDB checkpointing dir per TM
Date Fri, 26 Oct 2018 18:27:31 GMT
There is also state.backend.rocksdb.localdir.  Oddly, I can find the
documentation for it in the 1.5 docs
<https://ci.apache.org/projects/flink/flink-docs-release-1.5/dev/stream/state/checkpointing.html#state-backend-rocksdb-localdir>,
but not in the 1.6 docs
<https://ci.apache.org/projects/flink/flink-docs-release-1.6/dev/stream/state/checkpointing.html>.
The option is still in master
<https://github.com/apache/flink/blob/master/flink-state-backends/flink-statebackend-rocksdb/src/main/java/org/apache/flink/contrib/streaming/state/RocksDBOptions.java#L33-L37>,
and it is used
<https://github.com/apache/flink/blob/e62a7eabe34da42e4cb56d1b14905a3b9e9c9bd4/flink-state-backends/flink-statebackend-rocksdb/src/main/java/org/apache/flink/contrib/streaming/state/RocksDBStateBackend.java#L289>
.

On Fri, Oct 26, 2018 at 3:01 AM Andrey Zagrebin <andrey@data-artisans.com>
wrote:

> Hi Taher,
>
> TMs keep state locally while running, in this case RocksDB files already
> belong to TM.
> You can point it to the same NVME disk location on each node, relevant
> Flink options here are:
> - io.tmp.dirs
> - taskmanager.state.local.root-dirs
> This data is transient and has temporary nature. It does not survive a job
> failure.
>
> The checkpoint is a logical snapshot of the operator state for all
> involved TMs,
> so it belongs to the job and usually uploaded to a distributed file system
> available on all TMs.
> The location is set in Flink option ‘state.checkpoints.dir'.
> This way job can restore from it with different set of TMs.
>
> Best,
> Andrey
>
> > On 26 Oct 2018, at 08:29, Taher Koitawala <taher.koitawala@gslab.com>
> wrote:
> >
> > Hi All,
> >           Our current cluster configuration uses one HDD which is mainly
> for root and an other NVME disk per node, [1]we want make sure all TMs
> write their own RocksDB files to the NVME disk only, how do we do that?
> >
> > [2] Is it also possible to specify multiple directories per TMs so that
> we have an even spread when the RocksDB files are written?
> >
> > Thanks,
> > Taher Koitawala
>
>

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