?? 2010-06-01???? 15:00 -0500??Jonathan Shook?????? > Also, what are you meaning specifically by 'slow'? Which measurements > are you looking at. What are your baseline constraints for your test > system? > Actually, the problem is the utilizaton of resources(for a single machine): CPU: 700% / 1600% (16 cores) MEM: almost 100% (16GB) Swap: almost 0% Disk IO(write): 20~30MB / 200MB (7.2k raid5, benchmarked previously) NET: up to 100Mbps / 950Mbps (1Gbps, tuned and benchmarked previously)
So the speed of generating load, about 15M/s as reported before seems quite slow to me. I assume the system should get at least about 50MB/s of Disk IO speed. MEM? I don't think it plays a major role in this writing game. What's the bottleneck of the system? P.S about Consistency Level, I've tried ONE/DCQUORUM and found ONE is about 10-15% faster. However that's neither a promising result. Thanks! Kevin > > 2010/6/1 ?????? <shiyingjie1...@gmail.com>: > > Hi, It would be better if we know which Consistency Level did you choose, > > and what is the schema of test data? > > > > ?? 2010??6??1?? ????4:48??Shuai Yuan <yuansh...@supertool.net.cn>?????? > >> > >> 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 > >> > >> > > > > > -- Kevin Yuan www.yuan-shuai.info
