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Re: RocksDB checkpointing dir per TM


On Fri 26 Oct, 2018, 3:31 PM Andrey Zagrebin, <andrey@xxxxxxxxxxxxxxxxx> 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.


> On 26 Oct 2018, at 08:29, Taher Koitawala <taher.koitawala@xxxxxxxxx> 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