?? 2010-06-02???? 10:37 +0800??lwl?????? > is all the 4 servers' MEM almost 100%?
Yes > ?? 2010??6??2?? ????10:12??Shuai Yuan <yuansh...@supertool.net.cn>?? > ???? > Thanks lwl. > > Then is there anyway of tuning this, faster flush to disk or > else? > > Cheers, > > Kevin > > ?? 2010-06-02???? 09:57 +0800??lwl?????? > > > MEM: almost 100% (16GB) > > ----------------- > > maybe this is the bottleneck. > > writing concerns Memtable and SSTable in memory. > > > > ?? 2010??6??2?? ????9:48??Shuai Yuan > <yuansh...@supertool.net.cn>?? > > ???? > > ?? 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 > > > > > > > > > > > > > -- > Shuai Yuan ???? > Supertool Corp. ?????????????????????????? > > www.yuan-shuai.info > > > -- Shuai Yuan ???? Supertool Corp. ?????????????????????????? www.yuan-shuai.info
