Hi all, I'm testing writing speed of cassandra with 4 servers. I'm confused by the behavior of cassandra.
---env--- load-data app written in c++, using libcassandra (w/ modified batch insert) 20 writing threads in 2 processes running on 2 servers ---optimization--- 1.turn log level to INFO 2.JVM has 8G heap 3.32 concurrent read & 128 write in storage-conf.xml, other cache enlarged as well. ---result--- 1-monitoring by `date;nodetool -h host ring` I add all load together and measure the writing speed by (load_difference / time_difference), and I get about 15MB/s for the whole cluster. 2-monitoring by `iostat -m 10` I can watch the disk_io from the system level and have about 10MB/s - 65MB/s for a single machine. Very big variance over time. 3-monitoring by `iptraf -g` In this way I watch the communication between servers and get about 10MB/s for a single machine. ---opinion--- So, have you checked the writing speed of cassandra? I feel it's quite slow currently. Could anyone confirm this is the normal writing speed of cassandra, or please provide someway of improving it? -- Kevin Yuan www.yuan-shuai.info
