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What is 'Read Reuqests' on OpsCenter exaclty?

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What is 'Read Reuqests' on OpsCenter exaclty?

Bongseo Jang
I have cassandra 2.1 + OpsCenter 5.1.1 and test them.

When I monitored with opscenter 'read requests' graph, it seems the number on the graph is not what I expected, the number of client requests or responses.

I recorded actual number of client request and compare it with graph, then found they're different. The number on the graph is about 4 times larger than what the client claimed.

So, my question is what 'Read Reuqests' on OpsCenter counts exaclty ?

Thanks !

--
Regards,
Jang.

 a sound mind in a sound body
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Re: What is 'Read Reuqests' on OpsCenter exaclty?

Carlos Rolo
Probably it takes in account the read repair, plus a read that have consistency != 1 will produce reads on other machines (which are taken in account). I don't know the internals of opscenter but I would assume that this is the case.

If you want to test it further, disable read_repair, and make all your reads with CL=ONE. Then your client and Opscenter should match.

PS: Speculative_retry could also send reads over to more machines.

Regards,

Carlos Juzarte Rolo
Cassandra Consultant
 
Pythian - Love your data

rolo@pythian | Twitter: cjrolo | Linkedin: linkedin.com/in/carlosjuzarterolo
Mobile: +31 6 159 61 814 | Tel: +1 613 565 8696 x1649

On Thu, Apr 23, 2015 at 10:34 AM, Bongseo Jang <[hidden email]> wrote:
I have cassandra 2.1 + OpsCenter 5.1.1 and test them.

When I monitored with opscenter 'read requests' graph, it seems the number on the graph is not what I expected, the number of client requests or responses.

I recorded actual number of client request and compare it with graph, then found they're different. The number on the graph is about 4 times larger than what the client claimed.

So, my question is what 'Read Reuqests' on OpsCenter counts exaclty ?

Thanks !

--
Regards,
Jang.

 a sound mind in a sound body


--



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Re: What is 'Read Reuqests' on OpsCenter exaclty?

Sebastian Estevez

Carlos is right:

Read Requests - The number of read requests per second on the coordinator nodes, analogous to client reads. Monitoring the number of requests over a given time period reveals system read workload and usage patterns.

Avg - The average of values recorded during a time interval.

A future version of OpsC will include tooltips with these descriptions for better clarity.

On Apr 23, 2015 6:30 AM, "Carlos Rolo" <[hidden email]> wrote:
Probably it takes in account the read repair, plus a read that have consistency != 1 will produce reads on other machines (which are taken in account). I don't know the internals of opscenter but I would assume that this is the case.

If you want to test it further, disable read_repair, and make all your reads with CL=ONE. Then your client and Opscenter should match.

PS: Speculative_retry could also send reads over to more machines.

Regards,

Carlos Juzarte Rolo
Cassandra Consultant
 
Pythian - Love your data

rolo@pythian | Twitter: cjrolo | Linkedin: linkedin.com/in/carlosjuzarterolo
Mobile: +31 6 159 61 814 | Tel: <a href="tel:%2B1%20613%20565%208696%20x1649" value="+16135658696" target="_blank">+1 613 565 8696 x1649

On Thu, Apr 23, 2015 at 10:34 AM, Bongseo Jang <[hidden email]> wrote:
I have cassandra 2.1 + OpsCenter 5.1.1 and test them.

When I monitored with opscenter 'read requests' graph, it seems the number on the graph is not what I expected, the number of client requests or responses.

I recorded actual number of client request and compare it with graph, then found they're different. The number on the graph is about 4 times larger than what the client claimed.

So, my question is what 'Read Reuqests' on OpsCenter counts exaclty ?

Thanks !

--
Regards,
Jang.

 a sound mind in a sound body


--



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Re: What is 'Read Reuqests' on OpsCenter exaclty?

Bongseo Jang
Thanks a lot Carlos, Sebastian :-)

My test was with 1 node/1 replica settings, on which I assumed client request = read request on the graph. Because there seems no read_repair and already CL=ONE in my case, I need more explanation, don't I? Or can any other internals be still involved?

Do you have more suggestions? I want to design new test narrowing the gap on the suggestions.

On 24 April 2015 at 00:23, Sebastian Estevez <[hidden email]> wrote:

Carlos is right:

Read Requests - The number of read requests per second on the coordinator nodes, analogous to client reads. Monitoring the number of requests over a given time period reveals system read workload and usage patterns.

Avg - The average of values recorded during a time interval.

A future version of OpsC will include tooltips with these descriptions for better clarity.

On Apr 23, 2015 6:30 AM, "Carlos Rolo" <[hidden email]> wrote:
Probably it takes in account the read repair, plus a read that have consistency != 1 will produce reads on other machines (which are taken in account). I don't know the internals of opscenter but I would assume that this is the case.

If you want to test it further, disable read_repair, and make all your reads with CL=ONE. Then your client and Opscenter should match.

PS: Speculative_retry could also send reads over to more machines.

Regards,

Carlos Juzarte Rolo
Cassandra Consultant
 
Pythian - Love your data

rolo@pythian | Twitter: cjrolo | Linkedin: linkedin.com/in/carlosjuzarterolo
Mobile: +31 6 159 61 814 | Tel: <a href="tel:%2B1%20613%20565%208696%20x1649" value="+16135658696" target="_blank">+1 613 565 8696 x1649

On Thu, Apr 23, 2015 at 10:34 AM, Bongseo Jang <[hidden email]> wrote:
I have cassandra 2.1 + OpsCenter 5.1.1 and test them.

When I monitored with opscenter 'read requests' graph, it seems the number on the graph is not what I expected, the number of client requests or responses.

I recorded actual number of client request and compare it with graph, then found they're different. The number on the graph is about 4 times larger than what the client claimed.

So, my question is what 'Read Reuqests' on OpsCenter counts exaclty ?

Thanks !

--
Regards,
Jang.

 a sound mind in a sound body


--






--
Regards,
Jang.

 a sound mind in a sound body
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Re: What is 'Read Reuqests' on OpsCenter exaclty?

Carlos Rolo
Let me try to reproduce your test and get back wiith some results.

Regards,

Carlos Juzarte Rolo
Cassandra Consultant
 
Pythian - Love your data

rolo@pythian | Twitter: cjrolo | Linkedin: linkedin.com/in/carlosjuzarterolo
Mobile: +31 6 159 61 814 | Tel: +1 613 565 8696 x1649

On Fri, Apr 24, 2015 at 2:35 AM, Bongseo Jang <[hidden email]> wrote:
Thanks a lot Carlos, Sebastian :-)

My test was with 1 node/1 replica settings, on which I assumed client request = read request on the graph. Because there seems no read_repair and already CL=ONE in my case, I need more explanation, don't I? Or can any other internals be still involved?

Do you have more suggestions? I want to design new test narrowing the gap on the suggestions.

On 24 April 2015 at 00:23, Sebastian Estevez <[hidden email]> wrote:

Carlos is right:

Read Requests - The number of read requests per second on the coordinator nodes, analogous to client reads. Monitoring the number of requests over a given time period reveals system read workload and usage patterns.

Avg - The average of values recorded during a time interval.

A future version of OpsC will include tooltips with these descriptions for better clarity.

On Apr 23, 2015 6:30 AM, "Carlos Rolo" <[hidden email]> wrote:
Probably it takes in account the read repair, plus a read that have consistency != 1 will produce reads on other machines (which are taken in account). I don't know the internals of opscenter but I would assume that this is the case.

If you want to test it further, disable read_repair, and make all your reads with CL=ONE. Then your client and Opscenter should match.

PS: Speculative_retry could also send reads over to more machines.

Regards,

Carlos Juzarte Rolo
Cassandra Consultant
 
Pythian - Love your data

rolo@pythian | Twitter: cjrolo | Linkedin: linkedin.com/in/carlosjuzarterolo
Mobile: +31 6 159 61 814 | Tel: <a href="tel:%2B1%20613%20565%208696%20x1649" value="+16135658696" target="_blank">+1 613 565 8696 x1649

On Thu, Apr 23, 2015 at 10:34 AM, Bongseo Jang <[hidden email]> wrote:
I have cassandra 2.1 + OpsCenter 5.1.1 and test them.

When I monitored with opscenter 'read requests' graph, it seems the number on the graph is not what I expected, the number of client requests or responses.

I recorded actual number of client request and compare it with graph, then found they're different. The number on the graph is about 4 times larger than what the client claimed.

So, my question is what 'Read Reuqests' on OpsCenter counts exaclty ?

Thanks !

--
Regards,
Jang.

 a sound mind in a sound body


--






--
Regards,
Jang.

 a sound mind in a sound body


--



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Re: What is 'Read Reuqests' on OpsCenter exaclty?

Bongseo Jang
You're quite right. I missed important thing first.

I found a mistake in my program while making test case. It turns out that the original program has 3~4 selects for non-existing row keys plus a select for existing row key. It was intended to do nothing but for next tests. My original test  counted only selects for existing row key but opscenter graph showed real number of request. That's it

Thank you again ~

On 24 April 2015 at 16:01, Carlos Rolo <[hidden email]> wrote:
Let me try to reproduce your test and get back wiith some results.

Regards,

Carlos Juzarte Rolo
Cassandra Consultant
 
Pythian - Love your data

rolo@pythian | Twitter: cjrolo | Linkedin: linkedin.com/in/carlosjuzarterolo
Mobile: +31 6 159 61 814 | Tel: +1 613 565 8696 x1649

On Fri, Apr 24, 2015 at 2:35 AM, Bongseo Jang <[hidden email]> wrote:
Thanks a lot Carlos, Sebastian :-)

My test was with 1 node/1 replica settings, on which I assumed client request = read request on the graph. Because there seems no read_repair and already CL=ONE in my case, I need more explanation, don't I? Or can any other internals be still involved?

Do you have more suggestions? I want to design new test narrowing the gap on the suggestions.

On 24 April 2015 at 00:23, Sebastian Estevez <[hidden email]> wrote:

Carlos is right:

Read Requests - The number of read requests per second on the coordinator nodes, analogous to client reads. Monitoring the number of requests over a given time period reveals system read workload and usage patterns.

Avg - The average of values recorded during a time interval.

A future version of OpsC will include tooltips with these descriptions for better clarity.

On Apr 23, 2015 6:30 AM, "Carlos Rolo" <[hidden email]> wrote:
Probably it takes in account the read repair, plus a read that have consistency != 1 will produce reads on other machines (which are taken in account). I don't know the internals of opscenter but I would assume that this is the case.

If you want to test it further, disable read_repair, and make all your reads with CL=ONE. Then your client and Opscenter should match.

PS: Speculative_retry could also send reads over to more machines.

Regards,

Carlos Juzarte Rolo
Cassandra Consultant
 
Pythian - Love your data

rolo@pythian | Twitter: cjrolo | Linkedin: linkedin.com/in/carlosjuzarterolo
Mobile: +31 6 159 61 814 | Tel: <a href="tel:%2B1%20613%20565%208696%20x1649" value="+16135658696" target="_blank">+1 613 565 8696 x1649

On Thu, Apr 23, 2015 at 10:34 AM, Bongseo Jang <[hidden email]> wrote:
I have cassandra 2.1 + OpsCenter 5.1.1 and test them.

When I monitored with opscenter 'read requests' graph, it seems the number on the graph is not what I expected, the number of client requests or responses.

I recorded actual number of client request and compare it with graph, then found they're different. The number on the graph is about 4 times larger than what the client claimed.

So, my question is what 'Read Reuqests' on OpsCenter counts exaclty ?

Thanks !

--
Regards,
Jang.

 a sound mind in a sound body


--






--
Regards,
Jang.

 a sound mind in a sound body


--






--
Regards,
Jang.

 a sound mind in a sound body
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Re: What is 'Read Reuqests' on OpsCenter exaclty?

Bongseo Jang
I can see two numbers matches when the redundant selects are removed with 1 node/1 replica settings.

On 24 April 2015 at 19:09, Bongseo Jang <[hidden email]> wrote:
You're quite right. I missed important thing first.

I found a mistake in my program while making test case. It turns out that the original program has 3~4 selects for non-existing row keys plus a select for existing row key. It was intended to do nothing but for next tests. My original test  counted only selects for existing row key but opscenter graph showed real number of request. That's it

Thank you again ~

On 24 April 2015 at 16:01, Carlos Rolo <[hidden email]> wrote:
Let me try to reproduce your test and get back wiith some results.

Regards,

Carlos Juzarte Rolo
Cassandra Consultant
 
Pythian - Love your data

rolo@pythian | Twitter: cjrolo | Linkedin: linkedin.com/in/carlosjuzarterolo
Mobile: +31 6 159 61 814 | Tel: +1 613 565 8696 x1649

On Fri, Apr 24, 2015 at 2:35 AM, Bongseo Jang <[hidden email]> wrote:
Thanks a lot Carlos, Sebastian :-)

My test was with 1 node/1 replica settings, on which I assumed client request = read request on the graph. Because there seems no read_repair and already CL=ONE in my case, I need more explanation, don't I? Or can any other internals be still involved?

Do you have more suggestions? I want to design new test narrowing the gap on the suggestions.

On 24 April 2015 at 00:23, Sebastian Estevez <[hidden email]> wrote:

Carlos is right:

Read Requests - The number of read requests per second on the coordinator nodes, analogous to client reads. Monitoring the number of requests over a given time period reveals system read workload and usage patterns.

Avg - The average of values recorded during a time interval.

A future version of OpsC will include tooltips with these descriptions for better clarity.

On Apr 23, 2015 6:30 AM, "Carlos Rolo" <[hidden email]> wrote:
Probably it takes in account the read repair, plus a read that have consistency != 1 will produce reads on other machines (which are taken in account). I don't know the internals of opscenter but I would assume that this is the case.

If you want to test it further, disable read_repair, and make all your reads with CL=ONE. Then your client and Opscenter should match.

PS: Speculative_retry could also send reads over to more machines.

Regards,

Carlos Juzarte Rolo
Cassandra Consultant
 
Pythian - Love your data

rolo@pythian | Twitter: cjrolo | Linkedin: linkedin.com/in/carlosjuzarterolo
Mobile: +31 6 159 61 814 | Tel: <a href="tel:%2B1%20613%20565%208696%20x1649" value="+16135658696" target="_blank">+1 613 565 8696 x1649

On Thu, Apr 23, 2015 at 10:34 AM, Bongseo Jang <[hidden email]> wrote:
I have cassandra 2.1 + OpsCenter 5.1.1 and test them.

When I monitored with opscenter 'read requests' graph, it seems the number on the graph is not what I expected, the number of client requests or responses.

I recorded actual number of client request and compare it with graph, then found they're different. The number on the graph is about 4 times larger than what the client claimed.

So, my question is what 'Read Reuqests' on OpsCenter counts exaclty ?

Thanks !

--
Regards,
Jang.

 a sound mind in a sound body


--






--
Regards,
Jang.

 a sound mind in a sound body


--






--
Regards,
Jang.

 a sound mind in a sound body



--
Regards,
Jang.

 a sound mind in a sound body
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RE: What is 'Read Reuqests' on OpsCenter exaclty?

SEAN_R_DURITY

Just to add to this. It seems that reads done for authentication and authorization (using the built-in security classes) are included in the read request counts.

 

 

Sean Durity – Cassandra Admin, Big Data Team

To engage the team, create a request

 

From: Bongseo Jang [mailto:[hidden email]]
Sent: Friday, April 24, 2015 6:13 AM
To: [hidden email]
Subject: Re: What is 'Read Reuqests' on OpsCenter exaclty?

 

I can see two numbers matches when the redundant selects are removed with 1 node/1 replica settings.

 

On 24 April 2015 at 19:09, Bongseo Jang <[hidden email]> wrote:

You're quite right. I missed important thing first.

 

I found a mistake in my program while making test case. It turns out that the original program has 3~4 selects for non-existing row keys plus a select for existing row key. It was intended to do nothing but for next tests. My original test  counted only selects for existing row key but opscenter graph showed real number of request. That's it

 

Thank you again ~

 

On 24 April 2015 at 16:01, Carlos Rolo <[hidden email]> wrote:

Let me try to reproduce your test and get back wiith some results.


Regards,

 

Carlos Juzarte Rolo

Cassandra Consultant

 

Pythian - Love your data

 

rolo@pythian | Twitter: cjrolo | Linkedin: linkedin.com/in/carlosjuzarterolo

Mobile: +31 6 159 61 814 | Tel: +1 613 565 8696 x1649

 

On Fri, Apr 24, 2015 at 2:35 AM, Bongseo Jang <[hidden email]> wrote:

Thanks a lot Carlos, Sebastian :-)

 

My test was with 1 node/1 replica settings, on which I assumed client request = read request on the graph. Because there seems no read_repair and already CL=ONE in my case, I need more explanation, don't I? Or can any other internals be still involved?

 

Do you have more suggestions? I want to design new test narrowing the gap on the suggestions.

 

On 24 April 2015 at 00:23, Sebastian Estevez <[hidden email]> wrote:

Carlos is right:

Read Requests - The number of read requests per second on the coordinator nodes, analogous to client reads. Monitoring the number of requests over a given time period reveals system read workload and usage patterns.

Avg - The average of values recorded during a time interval.

A future version of OpsC will include tooltips with these descriptions for better clarity.

On Apr 23, 2015 6:30 AM, "Carlos Rolo" <[hidden email]> wrote:

Probably it takes in account the read repair, plus a read that have consistency != 1 will produce reads on other machines (which are taken in account). I don't know the internals of opscenter but I would assume that this is the case.

If you want to test it further, disable read_repair, and make all your reads with CL=ONE. Then your client and Opscenter should match.

PS: Speculative_retry could also send reads over to more machines.


Regards,

 

Carlos Juzarte Rolo

Cassandra Consultant

 

Pythian - Love your data

 

rolo@pythian | Twitter: cjrolo | Linkedin: linkedin.com/in/carlosjuzarterolo

Mobile: +31 6 159 61 814 | Tel: <a href="tel:%2B1%20613%20565%208696%20x1649" target="_blank"> +1 613 565 8696 x1649

 

On Thu, Apr 23, 2015 at 10:34 AM, Bongseo Jang <[hidden email]> wrote:

I have cassandra 2.1 + OpsCenter 5.1.1 and test them.

 

When I monitored with opscenter 'read requests' graph, it seems the number on the graph is not what I expected, the number of client requests or responses.

 

I recorded actual number of client request and compare it with graph, then found they're different. The number on the graph is about 4 times larger than what the client claimed.

 

So, my question is what 'Read Reuqests' on OpsCenter counts exaclty ?

 

Thanks !

 

--

Regards,
Jang.

 a sound mind in a sound body

 

 

--

 



 

--

Regards,
Jang.

 a sound mind in a sound body

 

 

--

 



 

--

Regards,
Jang.

 a sound mind in a sound body



 

--

Regards,
Jang.

 a sound mind in a sound body




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