First off, congratulations on passing the ISM!

For the E20-555, the best place to start is the exam description here: https://education.emc.com/content/_common/docs/exam_descriptions/e20-555_TA_Isilon_Solutions_And_Design_Specialist_Exam.…

At the end of the description it lists the recommended training, which in this case includes 1 e-Learning and 2 VILTs:

• Isilon Fundamentals eLearning (links to free e-Learning)
• Isilon Infrastructure Solutions VILT
• Isilon Solution Design VILT

You don't mention which VILT you are using; it's possible that you might need to take more than one.

The Practice Test is also a good place to go, so you're on the right path there.

Another option is to ask specific questions here. If you're looking at a problem, either in the VILT or the Practice Test, you can post the question here, along with the work you've done to solve it, and an SME can take a look at it and help you out. There are plenty of past questions in this forum too, so you can search for other questions related to this exam.

Hi Kate,

thank you for your quick reply!

I'm using the recommended training from the exam description. Also I have done the e-Learning course and the Isilon Infrastructure Solutions VILT. Currently I'm at Module 3 of the Design VILT.

But there are no hints to formulas I need in the exam to size the customers requirements.

I have found a sample question:

The customer want to implement a X-Series cluster. They have 200 customers and they grow 30% per year. They have 200TB of storage utilized and they keep the patient data for 7 years. The customer want to use N+3 protection and the data shouldn't exceed 75% utilization.

I have to figure out, what the recommended minimal initial configuration is.

X200 or X400 nodes, size of the HDDs and the count of nodes needed.