Re: [***SPAM*** ] Re: writing speed test
Thanks Peter! In my test application, for each record, rowkey -> rand() * 4, about 64B column * 20 -> rand() * 20, about 320B I use batch_insert(rowkey, col*20) in thrift. Kevin Yuan ??: Peter Sch??ller ??: user@cassandra.apache.org : [***SPAM*** ] Re: writing speed test : Wed, 2 Jun 2010 10:44:52 +0200 Since this thread has now gone on for a while... As far as I can tell you never specify the characteristics of your writes. Evaluating expected write throughput in terms of "MB/s to disk" is pretty impossible if one does not know anything about the nature of the writes. If you're expecting 50 MB, is that reasonable? I don't know; if you're writing a gazillion one-byte values with shortish keys, 50 MB/seconds translates to a *huge* amounts of writes per second and you're likely to be CPU bound even in the most efficient implementation reasonably possible. If on the other hand you're writing large values (say slabs of 128k) you might more reasonably be expecting higher disk throughput. I don't have enough hands-on experience with cassandra to have a feel for the CPU vs. disk in terms of bottlenecking, and when we expect to bottleneck on what, but I can say that it's definitely going to matter quite a lot what *kind* of writes you're doing. This tends to be the case regardless of the database system.
Re: writing speed test
Since this thread has now gone on for a while... As far as I can tell you never specify the characteristics of your writes. Evaluating expected write throughput in terms of "MB/s to disk" is pretty impossible if one does not know anything about the nature of the writes. If you're expecting 50 MB, is that reasonable? I don't know; if you're writing a gazillion one-byte values with shortish keys, 50 MB/seconds translates to a *huge* amounts of writes per second and you're likely to be CPU bound even in the most efficient implementation reasonably possible. If on the other hand you're writing large values (say slabs of 128k) you might more reasonably be expecting higher disk throughput. I don't have enough hands-on experience with cassandra to have a feel for the CPU vs. disk in terms of bottlenecking, and when we expect to bottleneck on what, but I can say that it's definitely going to matter quite a lot what *kind* of writes you're doing. This tends to be the case regardless of the database system. -- / Peter Schuller aka scode
Re: [***SPAM*** ] Re: [***SPAM*** ] Re: [***SPAM*** ] Re: [***SPAM*** ] Re: writing speed test
Still seems MEM. However it's hard to convince that constantly writing(even great amount of data) needs so much MEM(16GB). The process is quite simple, input_data -> memtable -> flush to disk right? What does cassandra need so much MEM for? Thanks! ?? 2010-06-02 16:24 +0800??lwl?? > No. > But I did some capacity tests about another distributed system. > Your former test cost too much MEM, it was the bottleneck. > caches and JVM cost MEM, so I suggested to decrease them. > > > What is the bottleneck of your current test now? > > > ?? 2010??6??2?? 4:13??Shuai Yuan ?? > > Hi, > > I tried, > > 1-consistency level ZERO > > 2-JVM heap 4GB > > 3-normal Memtable cache > > and now I have about 30% improvment. > > However I want to know if you have also done w/r benchmark and > what's > the result? > > ?? 2010-06-02 11:35 +0800??lwl?? > > > and, why did you set "JVM has 8G heap"? > > 8g, seems too big. > > > > ?? 2010??6??2?? 11:20??lwl ?? > > 3.32 concurrent read & 128 write in > storage-conf.xml, other > > cache > > enlarged as well. > > > > > > > > maybe you can try to decrease the size of caches. > > > > ?? 2010??6??2?? 11:14??Shuai Yuan > > ?? > > > > > > ?? 2010-06-02 10:37 +0800??lwl?? > > > is all the 4 servers' MEM almost 100%? > > > > > > Yes > > > > > > > ?? 2010??6??2?? 10:12??Shuai Yuan > > ?? > > > > > > 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 > > > ?? > > > > > > > > ?? 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 > >
Re: [***SPAM*** ] Re: [***SPAM*** ] Re: [***SPAM*** ] Re: writing speed test
Hi, I tried, 1-consistency level ZERO 2-JVM heap 4GB 3-normal Memtable cache and now I have about 30% improvment. However I want to know if you have also done w/r benchmark and what's the result? ?? 2010-06-02 11:35 +0800??lwl?? > and, why did you set "JVM has 8G heap"? > 8g, seems too big. > > ?? 2010??6??2?? 11:20??lwl ?? > 3.32 concurrent read & 128 write in storage-conf.xml, other > cache > enlarged as well. > > > > maybe you can try to decrease the size of caches. > > ?? 2010??6??2?? 11:14??Shuai Yuan > ?? > > > ?? 2010-06-02 10:37 +0800??lwl?? > > is all the 4 servers' MEM almost 100%? > > > Yes > > > > ?? 2010??6??2?? 10:12??Shuai Yuan > ?? > > > > 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 > > ?? > > > > > > ?? 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 ?? > : > > > > > Hi, It would be better if we > know which > > Consistency Level > > > did you choose, > > > > > and what is the schema of test >
Re: [***SPAM*** ] Re: [***SPAM*** ] Re: writing speed test
?? 2010-06-02 10:37 +0800??lwl?? > is all the 4 servers' MEM almost 100%? Yes > ?? 2010??6??2?? 10:12??Shuai Yuan ?? > > 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 > ?? > > > > ?? 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 ?? : > > > > 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 > > ?? > > > >> > > > >> 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? >
Re: [***SPAM*** ] Re: writing speed test
is all the 4 servers' MEM almost 100%? 在 2010年6月2日 上午10:12，Shuai Yuan 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 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 : > > > > 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 > > 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 > > >
Re: [***SPAM*** ] Re: writing speed test
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 ?? > > ?? 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 ?? : > > > 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 > ?? > > >> > > >> 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
Re: writing speed test
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 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 : > > > 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 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 > > >
Re: writing speed test
?? 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 ?? : > > 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 ?? > >> > >> 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
Re: writing speed test
Also, what are you meaning specifically by 'slow'? Which measurements are you looking at. What are your baseline constraints for your test system? 2010/6/1 史英杰 : > 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 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 >> >> > >
Re: writing speed test
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 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 > > >
