EMC Interview Questions

1. What do you mean by EMC?

Ans. The term "EMC" refers to electromagnetic compatibility, which allows different electronic devices to function together without causing mutual interference. In an electromagnetic environment, EMC creates a link between electrical and electronic devices. Every electrical gadget can release a variety of electromagnetic fields. It eliminates the need for mutual contact and aids in limiting accidental generations and spread.

2. What is meant by LUN Masking, and why do we need it?

Ans. LUN refers to a logical unit number, which provides a host with an authenticated activity. Applying LUN is possible at the HBA Level, or HOST bus adapter. Further, LUN masking minimizes data loss and makes the LUN mask system unusable by other OS in addition to being used for writing volume labels at Windows-based servers.

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3. Explain briefly about the EMC environment.

Ans. The critical components utilized in the EMC environment are listed below. These include:

1. Providing Adapters
2. Information on the adapter
3. Updating firmware
4. Restart the adapter
5. Durable Bindings.

The following is an essential code:

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

“50060xy4411 c6c12: lpfc1t2”;

The 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. To answer your question, a logical reference that is valid for the entire physical disk is a logical unit number or LUN. A LUN represents a piece of a physical disk, disk volume, or storage subsystem.

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

Ans. A HBA's maximum IOPS can be computed using the formula below.

(Device Queue depth per LUN * (1 / Storage latency in ms/1000)))

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

Ans. The name servers in the devices are used mainly by Wmn zoning to either permit or prohibit access to the fabric.

The principal benefits of Wmn Zoning are as follows:

• The capacity to recable any fabric without the need for duplicate data.
• Assists in blocking any unknown or vulnerable access.

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

Ans. The following are the key differences between the soft and hard zoning.

• Soft zoning is applied in Software, whereas hard zoning is used in hardware.
• Hard zoning restricts the access to any zone from the external gadgets. On the other hand, soft zoning uses the filtering application to stop ports from external zones.
• The security vulnerability of hard zoning is well-designed, whereas the security exposure for soft zoning could be more effective. 

8. Define the device masking structure within Storage arrays.

Ans. The following functions are carried out by the device masking architecture, including

1. Assists in allocating and concealing access to any host and adapters
2. This aids in the storage of arrays and devices when connected to the fibre channel topology.
3. Assists in modifying the attributes and defining the host bus adapters.
4. Any privileged attributes connected to device masking objects are accessible to you.

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

Ans. The following are the main elements that will be taken into account when creating a San;

1. Preferring ISL to subscriber ratio
2. SAN Fan-in and SAN fan-out
3. Storage ports
4. Profiles for server input or output
5. Making use of fabric attributes
6. Requirements for continuity

Here, three distinct tiers will be utilized;

Level 1: 99.999% uptime with 5 minutes of annual downtime.

Tier 2 levels: 99.9% availability (8.8 hours on average per year, with a maximum of 13.1 hours)

Tier 3 levels: 3.7 days/year downtime with 99% availability.

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

Ans. The interrelation between rotational and latency speed are as follows:

Latency time = (1/((Rotational speed in Rotation per min/ 60)) * 0.5 * 1000 milliseconds

Latency and Rotation per minute:

HDD Spindle RPM Avg. Rotational Latency [milli secs]

• 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. The general techniques for accessing SAN storage from an array are listed below.

1. Verification using the host connectivity support matrix.
2. Planning
3. Offer connection
4. Select the volumes
5. Draw a zoning map.
6. Create Meta volumes as needed.
7. Map ports to storage arrays
8. LUN masks
9. Establish Zones
10. Find out using the server.

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

Ans. The formula is as follows;

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

13. You need to supply San storage with a Certain IOPS. How will you identify what kind of Disks you require?

• The number of input or output operations (IOPS) that a storage gadget can finish in a second is measured using input or output operations per second, or IOPs.
• For apps that rely on transactions, input or output according to the second operation is crucial.
• Operating input or output is highly dependent on the quantity of disk drives utilized.

To determine a hard disk drive's IOPS:

IOPS = ---------.

Average seek time + Average delay (latency)

To determine IOPS within a RAID:

(Total workload IOPS * % of the workload, i.e., read operations) + (Total workloads IOPS * % of workload that is read operations * RAID I/O penalty).

14. How is HDD capacity calculated?

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

Ans. Represents the number of buffers= BB_credits = [port speed] * [round trip time] / [Frame size].

16. What is meant by buffer-to-buffer (BB) credits? (New Qs)

Ans. The buffer-to-buffer credits or BB credits are helpful in transmission flow control through a Fibre Channel technology. They show the number of frames that a port stores. Moreover, the interface of the Fiber Channel uses buffer credits that make sure that all the packets reach their destination. To Flow-control technique to prevent frame drops in Fiber Channel transitions by avoiding buffer exhaust. Minimizing the BB credits provided to each port can improve the overall speed. It is what BB credits all about.

17. Name the load balancing policies helpful in Inter-Switch Links. (New Qs)

Ans. The following are the load balancing policies applicable in inter-switch links:

• DLS – The term dls refers to Dynamic Load Sharing. 
• DPS – The term DPS refers to Dynamic Path Selection 
• Frame-level load balancing

Conclusion

Thus, you have explored the frequently asked EMC interview questions and answers designed by the experts at HKR Trainings. These questions are helpful to enhance your skills in hardware gadgets for both freshers and experienced individuals. I hope you found this article on EMC interview questions helpful for your upcoming interviews in this field.