Am assuming you are not getting a hot spot in the ring using the OPP.
When running 0.7.4 with reduced concurrent reads if you see the read stage
backing up using nodetool tpstats and the output from iostats shows that the IO
system is not stressed then you should return the concurrent reads to the
recommended value.
Not sure why the recommendation changed, but how does 0.7.4 perform with the
recommended number of concurrent readers?
Out of interest can anyone talk about IO changes in 0.7.X that resulted in the
new recommendation?
Thanks
Aaron
On 16 Apr 2011, at 13:33, 魏金仙 wrote:
To make a comparation, 10 threads were run against the two workloads
seperately. below is the result of Cassandra0.7.4.
write heavy workload(i.e., write/read: 50%/50%)
median throughput: 5816 operations/second(i.e., 2908 writes and 2908 reads)
update latency:1.32ms read latency:1.81ms
read heavy workload(i.e., write/read: 5%/95%)
median throughput: 40 operations/second(i.e., 2 writes and 38 reads) update
latency:1.85ms read latency:90.43ms
and for cassandra0.6.6, the result is:
write heavy workload(i.e., write/read: 50%/50%)
median throughput: 3284 operations/second(i.e., 1642 writes and 1642 reads)
update latency:2.29ms read latency:3.51ms
read heavy workload(i.e., write/read: 5%/95%)
median throughput: 2759 operations/second(i.e., 2621 writes and 138 reads)
update latency:2.33ms read latency:3.53ms
all the tests were run in one environment. and most configurations of
cassandra are just as default, except that:we choose
orderPreservingPartitioner for all the tests and set concurrent_reads as 8(
which is the default value of 0.6.6 but the default value of 0.7.4 is 32) .
At 2011-04-16 06:53:01，Aaron Morton aa...@thelastpickle.com wrote:
Will need to know more about the number of requests, iostats etc. There is no
reason for it to run slower.
Aaron
On 16/04/2011, at 2:35 AM, 魏金仙 sei_...@126.com wrote:
I just deployed cassandra 0.7.4 as a 6-server cluster and tested its
performance via YCSB.
The result seems confusing when compared to that of Cassandra0.6.6. Under a
write heavy workload(i.e., write/read: 50%/50%), Cassandra0.7.4 obtains a
really satisfactory latency. I mean both the read latency and write latency
is much lower than those of Cassandra0.6.6.
However, under a read heavy workload(i.e., write/read:5%/95%),
Cassandra0.7.4 performs far worse than Cassandra0.6.6 does.
Did I miss something?
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