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HDFS, mail # user - Re: some ideas for QJM and NFS


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Azuryy Yu 2013-02-18, 06:53
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Azuryy Yu 2013-02-18, 07:22
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谢良 2013-02-18, 07:35
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Azuryy Yu 2013-02-18, 07:56
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谢良 2013-02-18, 08:02
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Azuryy Yu 2013-02-18, 08:19
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答复: 答复: 答复: some ideas for QJM and NFS
谢良 2013-02-18, 08:39
But it'll contend for I/O resources. when journal(...) is invoked in JN, there will be a flush(shouldFsync) operation, relying on Java's FileChannel.force(...) method, then turn into a f(data)sync system call.
So it's better to deploy JN on different nodes(e.g. SAS+Raid ?)

Regards,
Liang
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发件人: Azuryy Yu [[EMAIL PROTECTED]]
发送时间: 2013年2月18日 16:19
收件人: [EMAIL PROTECTED]
主题: Re: 答复: 答复: some ideas for QJM and NFS

I don't think this is an issue. QJM talks with JN  using RPC,  the default handlers are enough for both DN and JN in my testing.
On Mon, Feb 18, 2013 at 4:02 PM, 谢良 <[EMAIL PROTECTED]<mailto:[EMAIL PROTECTED]>> wrote:
IMHO, it's not a recommented deploy manner to deploy JN and DN into same nodes.

Regards,
Liang
________________________________
发件人: Azuryy Yu [[EMAIL PROTECTED]<mailto:[EMAIL PROTECTED]>]
发送时间: 2013年2月18日 15:56
收件人: [EMAIL PROTECTED]<mailto:[EMAIL PROTECTED]>
主题: Re: 答复: some ideas for QJM and NFS

All JNs are deployed on the same node with DN.
On Mon, Feb 18, 2013 at 3:35 PM, 谢良 <[EMAIL PROTECTED]<mailto:[EMAIL PROTECTED]>> wrote:
Hi Azuryy, just want to confirm one thing, your JN did not deploy on the same machines within DN, right ?

Regards,
Liang
________________________________
发件人: Azuryy Yu [[EMAIL PROTECTED]<mailto:[EMAIL PROTECTED]>]
发送时间: 2013年2月18日 15:22
收件人: [EMAIL PROTECTED]<mailto:[EMAIL PROTECTED]>
主题: Re: some ideas for QJM and NFS

Hi,

I did it on hadoop-2.0.3-alpha without HA as following:

[root@webdm test]# date +%Y-%m-%d_%H:%M:%S; hdfs dfs -put testspeed.tar.gz / ; date +%Y-%m-%d_%H:%M:%S
2013-02-18_15:20:01
13/02/18 15:20:02 WARN util.NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin-java classes where applicable
2013-02-18_15:20:30

so the performance is a little bit better than hadoop-1.0.4.

On Mon, Feb 18, 2013 at 2:53 PM, Azuryy Yu <[EMAIL PROTECTED]<mailto:[EMAIL PROTECTED]>> wrote:
Oh, yes, you are right, George. I'll probably do it in the next days.
On Mon, Feb 18, 2013 at 2:47 PM, George Datskos <[EMAIL PROTECTED]<mailto:[EMAIL PROTECTED]>> wrote:
Hi Azuryy,

So you have measurements for hadoop-1.0.4 and hadoop-2.0.3+QJM, but I think you should also measure hadoop-2.0.3 _wihout_ QJM so you can know for sure if the performance degrade is actually related to QJM or not.
George
Hi,

HarshJ is a good guy, I've seen this JIRA: https://issues.apache.org/jira/browse/HDFS-4508

I have a test cluster hadoop-1.0.4, I've upgrade to hadoop-2.0.3-alpha. mu cluster is very small, four nodes totally.

then I did some test on the original Hadoop and new Hadoop, the testing is very simple: I have a data file with 450MB, I just put it on the HDFS.

block size: 128MB, replica: 2

the following is the result:

[root@webdm test]# ll testspeed.tar.gz
-rw-r--r-- 1 root root 452M Feb 18 13:54 testspeed.tar.gz
[root@webdm test]#

//On the hadoop-1.0.4
[root@webdm test]# date +%Y-%m-%d_%H:%M:%S; hadoop dfs -put testspeed.tar.gz / ; date +%Y-%m-%d_%H:%M:%S
2013-02-18_13:54:24
Warning: $HADOOP_HOME is deprecated.
2013-02-18_13:54:58

//On the hadoop-2.0.3-alpha with QJM
[root@webdm test]# date +%Y-%m-%d_%H:%M:%S; hdfs dfs -put testspeed.tar.gz / ; date +%Y-%m-%d_%H:%M:%S
2013-02-18_14:13:29
13/02/18 14:13:30 WARN util.NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin-java classes where applicable
2013-02-18_14:14:33

I do think QJM HA feature affect the performance, because each writer from QJM, it will do: fence old writer; sync in-progress log; start new log segment; then write. only if writer received a successful response from a quorum of JNs, writer finished for this time.

But NFS HA just write log segment in the local and NFS, when it receive successful response from NFS, it finished this time.

So, I just suggest we always keep these two HA features in future, even in the stable release. which one should be used, which depends on yourself based on your infrastructure.

Thanks.
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Azuryy Yu 2013-02-18, 06:36