Hi Diane,
On 17/07/14 06:19, Diane Griffith wrote:
We have been struggling proving out linear read performance with our cassandra
configuration, that it is horizontally scaling. Wondering if anyone has any
suggestions for what minimal configuration and approach to use to demonstrate
this.
We were trying to go for a simple set up, so on the keyspace and/or column
families we went with the following settings thinking it was the minimal to
prove scaling:
replication_factor set to 1,
a RF of 1 means that any particular bit of data exists on exactly one node. So
if you are testing read speed by reading the same data item again and again as
fast as you can, then all the reads will be coming from the same one node, the
one that has that data item on it. In this situation adding more nodes won't
help. Maybe this isn't exactly how you are testing read speed, but perhaps you
are doing something analogous? I suggest you explain how you are measuring read
speed exactly.
Ciao, Duncan.
SimpleStrategy,
default consistency level,
default compaction strategy (size tiered),
but compacted down to 1 sstable per cf on each node (versus using leveled
compaction for read performance)
*Read Performance Results:*
1 client thread - 2 nodes > 1 node was seen but we couldn't show increased
performance adding more nodes i.e 4 nodes ! > 2 nodes
2 client threads - 2 nodes > 1 node still was true but again we couldn't show
increased performance adding more nodes i.e. 4 nodes ! > 2 nodes
10 client threads - this time 2 nodes < 1 node on performance numbers. 2 nodes
suffered from larger reduce throughput than 1 node was showing.
Where are we going wrong?
How have others shown horizontal scaling for reads?
Thanks,
Diane
