![]() I will use this policy is for Active/Passive arrays and many pseudo active/active arrays. Most Recently Used: The path used by a LUN is not be altered unless an event instructs the path to change.Servers/ hosts can also use multipathing for load balancing. Servers/ hosts use multipathing for failover from one path to the other when one path from the Servers/host to the SAN becomes unavailable, the host switches to another path. What are multi-pathing schemes and which one to use for optimal performance? Where n1e= number of edge switches, n2c= number of core switches, n3i=number of ISLġ1.Core Edge Fabric Nomenclature: n1e*n2c*n3i.Higher ROI meets RTO, RPO & SLA and helps with consolidation, utilization of storage, and ability to access any storage system from any host.I consider Core-Edge the most versatile form of SAN design.It makes the fabrics highly scalable, without disruption to service.Storage and other devices connect to the free ports on the edge switches, in some cases also connect directly to the core switch.This interconnects a number of “edge” switches.As the fabric has two or more “core” switches in the centre of the fabric,.This design includes redundant paths between switches,.Spindle RPM Average rotational latency ġ5,000 2.00 10. Latency time = (1/((Rotational Speed in RPM)/60)) * 0.5 * 1000 milliseconds The Rotational speed and latency time are related as follows: What is the relation between rotational speed and latency time? ![]() How will you calculate HDD Capacity?Ĭapacity = Heads X Cylinders X Sectors X Block Size 9. Total Approximate Drives = (RAID Group IOPS / (Hard Drive Type IOPS)) + Large Random I/O adjustment + Hot Spares + System Drives 8. If you know I/O load and IOPS, how will you calculate how many drives will be needed? Total Approximate Drives required = (RAID Group IOPS / (Hard Drive Type IOPS)) + Large Random I/O adjustment + Hot Spares + System Drives 7. How will you calculate the number of drives required? L = number of LUN presented to the host through this portĮxecution Throttle= (Maximum Storage Port Command Queue) / (Host Ports) 6. L is the quantity of LUNs in the storage group. I is the number of initiators per storage port Q = Storage Port Max Queue Depth / (I * L), Q is the Queue Depth =Execution Throttle= Maximum Number of simultaneous I/O for each LUN on a particular path to the Storage Port.Ĭalculation of the maximum queue depth: The queue depth is the number of I/O operations that can be run in parallel on a device. The queue depth is the maximum number of commands that can be queued on the system at the same time. Max IOPS an HBA Port can generate to any LUN = (Device Queue Depth per LUN * (1 / (Storage Latency in ms/1000))) How will you calculate Max IOPS an HBA Port can generate to any LUN? (Total Workload IOPS * Percentage of workload that is read operations) + (Total Workload IOPS * Percentage of workload that is read operations * RAID IO Penalty) 4. To calculate the IOPS of a Hard disk drive: IOPS performance is heavily dependent on the number and type of disk drives. IOPS is important for transaction-based applications. ![]() Input/output operations per second (IOPS) is the measure of how many input/output operations a storage device can complete within one second. How will you find what kind of disks you need? You need to provision SAN storage with a certain IOPS. How to calculate HDD capacity?Ĭapacity = Heads X Cylinders X Sectors X Block Size 3. Total Approximate Drives required = (RAID Group IOPS / (Hard Drive Type IOPS)) + Large Random I/O adjustment + Hot Spares + System Drives 2. As a SAN administrator, how will you tell your boss how many drives are required for a requirement? This course will help you to achieve excellence in this domain.ĮMC Interview Questions For Freshers 1. If you want to enrich your career and become a professional in EMC, then enroll in " EMC Training". What is the difference between Hard and Soft Zoning?.How will you discover SAN disks on Hosts?.Mindmajix offers Advanced EMC Interview Questions 2023 that helps you in cracking your interview & acquire your dream career as EMC Engineer So, You still have the opportunity to move ahead in your career in EMC Engineering. According to research, EMC has a progressive market share. There are a lot of opportunities from many reputed companies in the world. If you're looking for EMC Interview Questions for Experienced or Freshers, you are at the right place.
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