Riak 1.4 upgrade reorganizes levels one and two upon upgrade. This likely 
pushed data up into your level 5. 

No, there currently is no control on compaction I/O. 

Matthew

Sent from my iPhone

> On Dec 2, 2013, at 2:36 AM, Timo Gatsonides <[email protected]> wrote:
> 
> 
> I have upgraded two nodes in my cluster from 1.3.2 to 1.4.2. After the 
> upgrade it appears both started a compaction, as mentioned here: 
> https://github.com/basho/riak/blob/1.4/RELEASE-NOTES.md#leveldb-13-to-14-conversion.
>  In my case I think this may have also triggered compactions at level 5 
> (finally) - see this earlier thread about stale data not getting removed: 
> http://lists.basho.com/pipermail/riak-users_lists.basho.com/2013-September/013392.html.
>  Which is good as the 2TB drive dedicated for this data was almost filled 
> completely. After the compaction finished, some 12-16 hours later, about 
> 200Gb of data was removed.
> 
> Two questions remain:
> 1) can someone please confirm that indeed the upgrade from 1.3 to 1.4 
> triggered the compactions, all the way to the level 5 compactions?
> 2) is there some way to limit the I/O for the compactions?
> 
> The problem was that during the compaction the node was really slow to 
> respond (I took it out of the HAProxy config), the CPU load was no problem, 
> around 30% on a single core only, however the iowait was high. Using iostat I 
> noticed the disk continuously reading AND writing around 30Mb/s (normal, 
> spinning disk, SATA).
> 
> Kind regards,
> Timo
> 
> 
> 
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