EF & E-Series, SANtricity, and Related Plug-ins

Read latency

Fizzer

Hi All, my first post here so please excuse any innacuracies! I've had our EF2824 for a few days and have configured it, a 10GB switch and a new R740 esxi 6.5 host. It's hosting just a single 2TB datastore. It's all SSD.

 

I've spun up a windows server 2012 VM for performance testing on the host. Connectivity seems fine and at the moment it's just doing updates - nothing too heavy. onceit's finished I was intending to install benchmarking tools to check performance.

However I have noticed that , even while it's just prepping and write latency is fantastic, read latency is averaging about 50ms so I'm guessing that something is wrong...

I have configured jumbo frames (9000) throughout.

 

Attached are the performance stats from the device, controller B is taking most of the load and there are 2 latency values for each controller channel:


Controller B Drive Channel 1 (Internal) - seems fine (<2ms)

Controller B Host Channel 1 - abysmal (>60ms)

 

Does this indicate a network problem if the internal figures are good and (presumably) external figures are bad?

If so, how come write rates are normal? surely a network issue would be bi-directional?

 

I know I'll eventually get this sorted but any pointers would be gratefully received!

 

Kind regards

 

Andy

 

1 ACCEPTED SOLUTION

DannyL

Hi Andy,

 

I am going to refer you to the following article: https://kb.netapp.com/app/answers/answer_view/a_id/1074155/loc/en_US . With low queue depth / heavy read workloads, we recommend disabling the Delayed ACK setting to resolve the issue you may be facing.

 

Thanks,

Danny

View solution in original post

2 REPLIES 2

DannyL

Hi Andy,

 

I am going to refer you to the following article: https://kb.netapp.com/app/answers/answer_view/a_id/1074155/loc/en_US . With low queue depth / heavy read workloads, we recommend disabling the Delayed ACK setting to resolve the issue you may be facing.

 

Thanks,

Danny

View solution in original post

Fizzer

Hi Danny,

I meant to reply to this earlier today, that was indeed the problem. I disabled delayed ack on my host and it's sorted the issue.

Atto disk benchmark in a simple windows server is giving me some great throuput now.

Thanks for your help

Andy

Announcements
NetApp on Discord Image

We're on Discord, are you?

Live Chat, Watch Parties, and More!

Explore Banner

Meet Explore, NetApp’s digital sales platform

Engage digitally throughout the sales process, from product discovery to configuration, and handle all your post-purchase needs.

NetApp Insights to Action
I2A Banner
Public