We did some test on on Cassandra, and the benchmark is from Section 7 of the BigTable paper Bigtable: A Distributed Storage System for Structured Data, the benchmark task includes: random write, random read, sequential write, and sequential read. The test results made us puzzled. We use a cluster of 5 nodes (each node has a 4 cores cpu , 4G memory).The data for test is a table with 4,000,000 records each of which is 1000 bytes. The test results are as follows: Sequential write: 875124 ms Sequential read: 1972588 ms Random read: 43331738 ms Random write: 20193484 ms We wondered why the speed of sequential write are so faster than the speed of sequential read, and why the speed of sequential write are so faster than that of random write? We think that the speed of read should be faster than that of data write, but the results are just the opposite, would you please give us some explanations, thanks a lot!
2010-03-12 Bingbing Liu
