is all the 4 servers' MEM  almost 100%?

在 2010年6月2日 上午10:12,Shuai Yuan <yuanshuai@supertool.net.cn>写道:
Thanks lwl.

Then is there anyway of tuning this, faster flush to disk or else?

Cheers,

Kevin

在 2010-06-02三的 09:57 +0800,lwl写道:
> MEM: almost 100% (16GB)
> -----------------
> maybe this is the bottleneck.
> writing concerns Memtable and SSTable in memory.
>
> 在 2010年6月2日 上午9:48,Shuai Yuan <yuanshuai@supertool.net.cn>写
> 道:
>         在 2010-06-01二的 15:00 -0500,Jonathan Shook写道:
>         > 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 史英杰 <shiyingjie1983@gmail.com>:
>         > > Hi, It would be better if we know which Consistency Level
>         did you choose,
>         > > and what is the schema of test data?
>         > >
>         > > 在 2010年6月1日 下午4:48,Shuai Yuan
>         <yuanshuai@supertool.net.cn>写道:
>         > >>
>         > >> 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 袁帅
Supertool Corp. 北京学之途网络科技有限公司
www.yuan-shuai.info