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Question about Jumbo-Frames?

Babeztar
Occasional Advisor

Question about Jumbo-Frames?

What is best pratice about Jumbo-Frames?

 

We are at the point to build a Hyper-V infrastucture with a 7400. Because we are before production we are able to configure the size now.

Keep it default 1500 or set MTU Size to 9000?

 

Best regards

Thomas

 

9 REPLIES
Mr_NKC
Frequent Advisor

Re: Question about Jumbo-Frames?

If you are using jumbo frames, then set the MTU size to 9000

Regards,
NKC

I work for HP

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Re: Question about Jumbo-Frames?

Hi,

 

For Jumbo Frames you can use an MTU of 9000.

 

You can refer to the HP 3PAR StoreServ 7000 Storage SmartStart Software User's Guide using the link below:

 

http://h20565.www2.hp.com/hpsc/doc/public/display?docId=emr_na-c03606526

 

Regards,

 

PS

 

 

Regards,

PS
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Babeztar
Occasional Advisor

Re: Question about Jumbo-Frames?

Thanks for reply.

 

Sorry for missunderstanding maybe.

 

The question is: is it best pratice to configure MTU size to 9000 and use jumbo frames or it doesn´t matter?

 

Best regards

Thomas

 

 

 

 

 

Sheldon Smith
Honored Contributor

Re: Question about Jumbo-Frames?

It depends. How will you be using your 7000?

 

If you will be using iSCSI, then definitely Jumbo Frames all around. What it comes down to is, will you be using IP for larger than normal packets? If just normal TCP traffic, then there is no need to worry about large MTU size.

 

If there is ever a possibility, it may be a good idea to set all the network switches to handle Jumbo Frames. As far as I know, there is no penalty for a switch allowing large packets to traverse. Of course, there eventually has to be storage that can use Jumbo Frames; but at that time, your infrastructure would be ready.

 

Check with your network team to find out if there is any "cost" for the switches to be set to pass them.

 

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Babeztar
Occasional Advisor

Re: Question about Jumbo-Frames?

That´s what I´m looking for.

 

Yes, we are using our 3par via iSCSI on our Hyper-V fram.

 

So, we are on the way and spoke already to our network guys and looking forward to get it implemented.

We did already some iometer tests and I excited about the tests after.

 

I´ll let you know.

 

Best regards

Thomas

Babeztar
Occasional Advisor

Re: Question about Jumbo-Frames?

Hi tech-folks,

 

we did all our changes and configured jumbo frames on the network switches, host iscsi network adapters and on the 3par system to use MTU size 9000.

 

We ran the iometer test again and there are no performance changes. :-(

 

Schould´n we see an increased performance?

 

Best regards

Thomas

Sheldon Smith
Honored Contributor

Re: Question about Jumbo-Frames?

Probably need to seriously "up" your Iometer testing.

What was the environment? (test definition, number of workers, number of threads, etc.)


Note: While I work for Hewlett Packard Enterprise, all of my comments (whether noted or not), are my own and are not any official representation of the company.
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Babeztar
Occasional Advisor

Re: Question about Jumbo-Frames?

It comes like it should.

 

We did some more tests on this and our performance.

It figured out that we have some high low performance issue. We found that without jumbo we ran just a little bit slower but more stable in a performance view.

 

We checked with our network team and they found a lot off Tx and Rx flow control pause frames.

At the network backend wie run a nexus 5000, jumbo and flow control enabled.

 

We plan to run a test without flow control to see if problem goes away.

 

What is best practice with a 7400? Flow control on or off?

Is there something to configure at the 7400 iSCSI Port?

 

Best regards

Thomas

 

 

BD3
Occasional Collector

Re: Question about Jumbo-Frames?

If you plan on doing ISCSI on a 7400, you should just plan on running with a MTU of 1500.  There are not enough buffer to buffer credits in the card to go to a 9000 MTU if there is any level of respecable workload on the system.  It also really depends on the block size of your workloads as well.  If you try and run SQL server formatted NTFS on a 64k block size with jumbo frames enabled, performance will be inadiquate.  We have a very large VMware environment, and ISCSI + jumbo frames resulted in a large amount of pause frames causing significant performance degredation.

What really needs to happen is an adapter replacement to one that supports hardware based iscsi acceleration to get the performance.  We ended up just moving to FC to fix out issue.