EMC Interview Questions

Are you ready to upgrade your Electronics skills? Then you are at the right place to learn and become an expert in EMC technology. The right place to learn is HKR’s EMC interview questions and answer blog. This blog will help you to crack any tough interview and also gain some knowledge related to technology. EMC is a type of electronic device mainly used to adopt different electronic devices in their organizations. As per the recent report, more than 4.8% of the market depends on EMC applications. So now you know the importance of learning EMC and how big it is. So what you are waiting for? Let’s get into learning the top 15 EMC interview questions;

1. What do you mean by EMC?

Ans: EMC stands for Electromagnetic compatibility, which enables various electronic devices to work without the use of mutual interference. EMC establishes the bridge between electrical and electronic equipment in the electromagnetic environment. All electronic devices are very potential devices to emit different electromagnetic fields. This also helps to limit the unintentional generations, propagation, and operates without the need for mutual interfaces.

2. What is LUN Masking and why we need it?

Ans: LUN is a Logical unit number, which offers an authorized process available for some host. LUN can be implemented at the HBA level (HOST bus adapter).

The purpose of using LUN masking is to write volume labels at the windows based servers, and also renders the LUN mask system unusable by any other operating system and reduces the data loss.

3. Explain briefly about the EMC environment?

Ans: The below are the important building blocks used in the EMC environment such as;

1. List Adapters

2. Adapter information

3. Firmware maintenance

4. Reset Adapter

5. Persistent Bindings.

The important code is as follows;

Fcp-bind-WWNN = “50060XY484411 cdc11: ipfc0t1”,

“50060xy4411 c6c12: lpfc1t2”;

Sd.conf file looks like:

Name = “sd” parent = “ipfc” target =1 lun =0;

Name = “sd” parent = “ipfc” target =2 lun =0;

4. What is the LUN or logical unit number?

Ans: Logical unit number or LUN is a type of logical reference which will be applicable to the entire physical disk. LUN is a subset of a physical disk or disk volume or storage subsystem portion.

5. How will you calculate Max IOPS an HBA port can generate to buy any LUN?

Ans: Max IOPS an HBA can be calculated as follows;

Max IOPS = (Device Queue depth per LUN * (1 /Storage latency in ms/1000))).

6. What is Wmn Zoning? Mention the advantages of Wmn zoning?

Ans: Wmn zoning mainly makes use of the name servers in the devices this allows or blocks access to fabric.

The major advantages of using Wmn Zoning;

1. Ability to recable of any fabric without using any redo information.

2. Helps to halt any susceptible or unauthorized access.

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7. What is the difference between Hard and soft zoning?

Ans: The below table will explain the major difference between Soft and Hard Zone. hard and soft zoning

8. Explain the device masking architecture in Storage arrays?

Ans: The device masking architecture performs the below operations such as;

1. Helps you to assign and mask access to any host and adapters

2. Connected with the fiber channel topology this helps to store arrays and devices.

3. Helps to specify the host bus adapters and modify the properties.

4. You can access any privileged properties associated with device masking objects.

9. What factor you will consider for designing A san?

Ans: Below are the major factors that will be considered for designing a San;

1. Using ISL over subscription ratio

2. SAN Fan-in and San Fan-out

3. Storage ports

4. Server input or output profiles

5. Usage of fabric features

6. Continuity requirements

Three separate levels will be used here;

Tier 1 levels: 99.999% availability (5 mins of downtime/year).

Tier 2 levels: 99.9% of availability (8.8 hrs. average timing/year, 13.1 hrs. maximum)

Tier 3 levels: 99% of availability (3.7 downtime days/ year).

10. What is the relation between rotational speed and latency time?

Ans: The rotational speed and latency speed are interrelated as follows;

Latency time = (1/((Rotational speed in Rotation per minute/ 60)) * 0.5 * 1000 mili seconds

Latency and Rotation per minute:

HDD

Spindle RPM                                   average rotational latency [milli seconds]

7200                                                   4.17

10,000                                                3.0

15,000                                                2.0

 

11. List out all the generic methods to provision SAN storage from an array?

Ans: Below are the generic methods used to access SAN storage from an array

1. Validation with support matrix Host connectivity.

2. Planning

3. Provide connectivity

4. Pick volumes

5. Map out zoning

6. Make Meta volumes if necessary

7. Map to storage array ports

8. LUN masks

9. Create Zones

10. Discover on the server.

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12. How will you calculate the Number of Drives Required?

Ans: The formula is as follows;

Total approximate drives = (RAID groups IOPS / (Hard drive type IOPS)) + large Random I/O adjustment + Hot spares + System drives.

13. You need to provision San storage with a Certain Lops. How will you find what kind of Disks you need?

Ans: 1. Input or Output operations per second or (IOPS) is used to measure how many input or output operations in which the storage device can be completed within a second.

Input or output per the second operation is important for transaction-based applications.

Input or Output operation is heavily dependent on the number of disk drives used.

 

To calculate IOPS of any hard disk drive:

IOPS = ----------

Average latency + Average Seek time

To calculate IOPS in a RAID:

(Total workload IOPS * percentage of workload that is read operations) + (Total workloads IOPS * Percentage of workload that is read operations * RAID I/O penalty).

14. How to calculate HDD capacity?

Capacity = Heads X Cylinders X sectors X block Size.

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15. How will you calculate the Number of Buffers required?

Ans: Number of buffers: BB_credits = [port speed] * [round trip time] / [Frame size].

Final take:

HKR’s EMC interview questions and answers are specially designed for both fresher and experienced professionals. EMC is best suited for those who are having knowledge of hardware devices. I hope this blog may help a few of you learn and crack any EMC related interviews with any top company.

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Saritha Reddy
Saritha Reddy
Research Analyst
A technical lead content writer in HKR Trainings with an expertise in delivering content on the market demanding technologies like Networking, Storage & Virtualization,Cyber Security & SIEM Tools, Server Administration, Operating System & Administration, IAM Tools, Cloud Computing, etc. She does a great job in creating wonderful content for the users and always keeps updated with the latest trends in the market. To know more information connect her on Linkedin, Twitter, and Facebook.

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