DES-1D12 Specialist - Technology Architect Midrange Storage Solutions Exam Questions and Answers

The best Unity load balancing method to optimize performance in a customer environment with a limited number of open FC switch ports is Port to Core Affinity. This method will assign the same port to the same core when possible. This allows the same switching resources to be used in the same cores, which will optimize performance due to reduced latency. Priority and Round Robin methods will also provide load balancing, but they are not as effective in a limited port environment. Least I/O is not recommended in this situation, as it will not provide adequate load balancing.

"The engineer should design a system to handle all, or nearly all, IOPS in one particular tier"

A fully scaled-out Dell PowerStore T cluster requires at least two instances of PowerStore Manager to ensure high availability. This is because the PowerStore Manager provides a centralized management and monitoring interface for the cluster, and having multiple instances of it allows for redundancy in case one instance becomes unavailable.

The maximum capacity of a file system on a Dell Unity XT 380 can be up to 256 TB. This high capacity is possible due to the advanced storage features such as data reduction, data tiering and use of high-density drives. The file system capacity can be increased by adding more drives, and by configuring the storage pool and LUNs in a way that maximizes storage utilization and performance. It's important to note that this may vary depending on the specific version and software of the Dell Unity XT 380.

The Dell Unity XT 380F has a default spare space allocation of 4% of the total number of drives in a dynamic pool. So with 90x 1.92 TB SSDs, 4 drives will be allocated as spare space. These spare drives are used to automatically replace a failed drive, ensuring data availability and protection.

"SCOS 7.3, Distributed Sparing: eliminates the need for dedicated spares by giving customers the option to distribute sparing capacity across all drives in the array."

Throughput = Sized by type and number of ports to handle traffic

Latency = Time taken for an IO to be executed

IOPS = Amount IO generated by application

Queue depth = IOS in buffer waiting to be executed

(Converged Network Adapter for iSCSI) is the front-end protocol card in Dell Unity XT 380 that offloads processing to save CPU cycles for other operations. It enables the Unity XT 380 to handle iSCSI traffic, which reduces the workload on the host server's CPU and improves overall system performance.

Secure mapping (secmap) - a cache that contains all mappings between SIDs, and UID or GIDs used by a NAS server.

DELL PDF document about dynamic pools: h16289-dell_emc_unity-dynamic_pools.pdf

Page 20-21. The smallest RAID 5 stripe width the system supports is a 4+1. The smallest dynamic pool created with the RAID 5 4+1 configuration is 6 drives. The minimum drive count includes the number of drives specified in the stripe width, plus the hot spare capacity. The hot spare capacity is selected by the user at pool creation, and can either be set to 1 or 2 drives for every 32 drives in the pool.

Both Dell PowerStore T and Dell PowerStore X support the 10 GbE BaseT optional I/O module card type. This card provides 10 Gbps Ethernet connectivity and can be used to connect the storage array to a network. The other options are not supported by both models. 25 GbE and 32 Gb Fibre Channel are generally faster and used for high-performance systems, while 8 Gb Fibre Channel is an older standard, and not supported by Dell PowerStore T and Dell PowerStore X.

The Dell PowerStore appliance provides two methods to migrate storage resources within the same cluster: Assisted Migration and Volume Motion.

Assisted Migration: This method allows the administrator to manually initiate and control the migration process, and it allows for the migration of individual resources such as LUNs, file systems and snapshots.

Volume Motion: This method allows the administrator to move a LUN or file system from one storage pool to another on the same PowerStore appliance or within the same cluster. This is done without any disruption to the hosts accessing the data and it can be automated with the use of policies.

It's important to note that the Live Migrate and Migrate options are not available to migrate storage resources within the same cluster in Dell PowerStore.

The System Designer path of the size tool for Dell Unity XT uses predefined configurations that are based on array model capacity points, random workloads RAID type and drive type. This path is designed to make the sizing process quick and easy, providing recommended configurations that are optimized for specific array models and workloads. It allows the user to select an array model, and then it will provide a set of predefined configurations that meet the desired capacity, performance, and availability requirements.