Fwd: What are workers in IOmeter

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Fwd: What are workers in IOmeter

Jori Gielis

Dear Sir or Madam,



Me and my colleague are ICT students at Thomas More Geel in Belgium.
This year we are doing a 3 months internship at the company Valcosoft.
The company has given us a subject, this subject is SAN.

Currently we are in our tenth week and we are doing some tests with IO-meter.

We have a question about the amount of workers we have to use with IOmeter. How many workers do you need to test with and why? Because we thought the amount of workers needs to be equal to the amount of cores in the CPU. But we were testing with our SAN server with only one SAS drive (max average speed 140MB/s), we tested it with one worker and we got a result of 143MB/s. But if we are testing it with 8 workers we get a result of 580MB/s. But it is impossible to reach such a high speed with this SAS drive, so where does this value come from?


Ps. We are just using one SAN server (with only one drive). This SAN server is directly connected to a workstation with only one Ethernet (10Gbit) cable. We are not using any switch.



We hope you can help us.


Thanks in advance.


 

Yours faithfully


 

Jonas Deckers and Jori Gielis



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Re: Fwd: What are workers in IOmeter

Gruher, Joseph R

SANs typically have some cache memory on board, one scenario would be that you are getting cache hits and inflating your throughput.  How are your workers configured in terms of access range, read write pattern, and block size?  How is the SAN connected to the client, is it iSCSI or FCoE or what?  Are you accessing it as a raw block device or is there a filesystem in place?

 

Typically I use one worker per target as long as the worker is not saturating a CPU core.  If you attach multiple workers to the same target and run sequential workloads you have the potential for weird behavior as the workers can access the same data range in close succession and generate a lot of cache hits.

 

-Joe

 

From: Jori Gielis [mailto:[hidden email]]
Sent: Tuesday, May 13, 2014 12:35 AM
To: [hidden email]
Subject: [Iometer-user] Fwd: What are workers in IOmeter

 

 

Dear Sir or Madam,

 

 

Me and my colleague are ICT students at Thomas More Geel in Belgium.
This year we are doing a 3 months internship at the company Valcosoft.
The company has given us a subject, this subject is SAN.
Currently we are in our tenth week and we are doing some tests with IO-meter.

We have a question about the amount of workers we have to use with IOmeter. How many workers do you need to test with and why? Because we thought the amount of workers needs to be equal to the amount of cores in the CPU. But we were testing with our SAN server with only one SAS drive (max average speed 140MB/s), we tested it with one worker and we got a result of 143MB/s. But if we are testing it with 8 workers we get a result of 580MB/s. But it is impossible to reach such a high speed with this SAS drive, so where does this value come from?

 

Ps. We are just using one SAN server (with only one drive). This SAN server is directly connected to a workstation with only one Ethernet (10Gbit) cable. We are not using any switch.

 

 

We hope you can help us.

 

Thanks in advance.

 

 

Yours faithfully

 

 

Jonas Deckers and Jori Gielis

 


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Get unparalleled scalability from the best Selenium testing platform available
Simple to use. Nothing to install. Get started now for free."
http://p.sf.net/sfu/SauceLabs
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