EMC E20-390 - Questions & Answers

Explanation:
Spanned volumes - spanned volumes use disk space from 2 to 32 disks. The amount of space used on the individual disks may vary. When data is written to a spanned volume, the portion of the volume residing on the first disk is filled first, and then data is written to the next disk in the volume. If any disk fails in the volume, then all data stored on that volume becomes unavailable. A spanned volume uses multiple disks, but does not improve disk performance.

Explanation:

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Explanation:
Native ESX/ESXi Multipath is managed via the configuration of a failover policy. Policy options are:

MRU (Most Recently Used) uses last active path, and does not fail back when a path is restored Fixed (Preferred path) reverts back to preferred path when it is restored to service Round Robin rotates the path selection between all available paths and enables basic load balancing across the paths.

This algorithm is not adaptive, so it will flip from one channel to the other with no regard for the work load unlike PowerPath, nor is it responsive to queue depth. NotE. Prior to vSphere, there was no way to load balance a LUN indigenously and customers needed to statically distribute LUNs across paths.

Explanation:
ALUA (Asymmetric Logical Unit Access) is a request forwarding implementation. In other words, the LUN is still owned by a single SP however, if I/O is received by an SP that does not own a LUN, that I/O is redirected to the owning SP. It 's redirected using a communication method to pass I/O to the other SP.

Explanation:
For example, if you have Flash (SSD) disks, SAS disks, and NL-SAS disks in the pool, the Flash disks form a tier, the SAS disks form a tier, and the NL-SAS disks form a tier. Based on your input or internally computed usage statistics, portions of LUNs ( 1GB slices) can be moved between tiers to maintain a service level close to the highest performing storage tier in the pool, even when some portion of the pool consists of lower performing (less expensive) disks. The tiers from highest to lowest are Flash, SAS, and NL-SAS. FAST is not supported for RAID groups because all the disks in a RAID group, unlike in a pool, must be of the same type (all Flash, all FC, or all SATA). The lowest performing disks in a RAID group determine a RAID group's overall performance.

Explanation:
For all Linux environments, EMC supports up to 16 Fibre Channel initiator ports on a single host. The host initiators may be single or dual channel HBAs.

Explanation:
There is a limitation in exporting a subdirectory and setting a quota on a file system from Windows 2000/2003/08. You will not see a quotas tab when exporting at the subdirectory level.