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From Chris Lohfink <clohf...@blackbirdit.com>
Subject Re: Cassandra JBOD disk configuration
Date Tue, 09 Sep 2014 19:14:11 GMT
It can get really unbalanced with STCS.  Whats more is even if there was a disk that could
fit the 600gb sstable it doesn't pay attention to space (first) so may pick the 75% full one
over the 10% one.  Its a better idea to use LCS with it unless data model really needs it
in which case monitor it carefully.  If you want to more completely utilize your disks you
will probably just want to use RAID.  I imagine you would get far better performance out of
JBOD though... "It Depends"

Chris

On Sep 4, 2014, at 4:48 AM, Hannu Kröger <hkroger@gmail.com> wrote:

> Hi,
> 
> Let's imagine that I have one keyspace with one big table configured with size tiered
compaction strategy and nothing else. The disk configuration would to have 10x 500GB disks,
each mounted to separate directory.
> 
> Each directory would then be configured as a separate entry in cassandra.yaml.
> 
> Over time data accumulates and I have at some point 4x 300GB sstables that the cassandra
would like to compact to one 1,2 TB sstable.
> 
> Since each directory has max 500GB disk space, that would not work. Right?
> 
> Is JBOD with more than 2 disks really usable with STCS? Probably LCS would the only way
to go in this case?
> 
> Cheers,
> Hannu 


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