EMC E10-001 Online Practice Questions and Exam Preparation

EMC E10-001 Online Questions & Answers

• Question 61:

  What is true about parity-based RAID?

  A. Parity is updated each time a write is performed
  B. Parity is read each time a read is performed
  C. Parity is updated only when writes fill a stripe
  D. Parity is updated each time when both reads and writes are performed
  A. Parity is updated each time a write is performed

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  Compared to mirroring, parity implementation considerably reduces the cost associated with data protection. Consider an example of a parity RAID configuration with five disks where four disks hold data, and the fifth holds the parity

  information. In this example, parity requires only 25 percent extra disk space compared to mirroring, which requires 100 percent extra disk space. However, there are some disadvantages of using parity.

  Parity information is generated from data on the data disk. Therefore, parity is recalculated every time there is a change in data. This recalculation is time-consuming and affects the performance of the RAID array.

  When choosing a RAID type, it is imperative to consider its impact on disk performance and application IOPS. In both mirrored and parity RAID configurations, every write operation translates into more I/O overhead for the disks, which is

  referred to as a write penalty. In a RAID 1 implementation, every write operation must be performed on two disks configured as a mirrored pair, whereas in a RAID 5 implementation, a write operation may manifest as four I/O operations.

  When performing I/Os to a disk configured with RAID 5, the controller has to read, recalculate, and write a parity segment for every data write operation.

  EMC E10-001 Student Resource Guide. Module 3: Data Protection - RAID

• Question 62:

  Where does a host-based volume manager map a file system block?

  A. Sectors
  B. Logical Extent
  C. Tracks
  D. Physical Extent
  B. Logical Extent

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  File System

  

  The following list shows the process of mapping user files to the disk storage that uses an LVM:

  1.

  Files are created and managed by users and applications.

  2.

  These files reside in the file systems.

  3.

  The file systems are mapped to file system blocks.

  4.

  The file system blocks are mapped to logical extents of a logical volume.

  5.

  These logical extents in turn are mapped to the disk physical extents either by the operating system or by the LVM.

  6.

  These physical extents are mapped to the disk sectors in a storage subsystem. If there is no LVM, then there are no logical extents. Without LVM, file system blocks are directly mapped to disk sectors. EMC E10-001 Student Resource Guide. Module 2: Data Center Environment

• Question 63:

  Click on the calculator icon in the upper left corner.

  An eight-disk RAID 6 set has a stripe size of 192 KB. What is the stripe depth?

  A. 24 KB
  B. 32 KB
  C. 48 KB
  D. 64 KB
  B. 32 KB

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  RAID Technique - Striping

  Strip size (also called stripe depth) describes the number of blocks in a strip, and is the maximum amount of data that can be written to or read from a single disk in the set, assuming that the accessed data starts at the beginning of the strip.

  All strips in a stripe have the same number of blocks. Having a smaller strip size means that the data is broken into smaller pieces while spread across the disks.

  Stripe size is a multiple of strip size by the number of data disks in the RAID set. For example, in a five disk striped RAID set with a strip size of 64KB, the stripe size is 320 KB (64KB x 5). Stripe width refers to the number of data strips in a

  stripe. Striped RAID does not provide any data protection unless parity or mirroring is used.

  For parity RAID, the stripe size calculation does not include the parity strip. For example in a five (4 + 1) disk parity RAID set with a strip size of 64 KB, the stripe size will be 256 KB (64 KB x 4).

  Calculation

  RAID6 = 2x Parity

  8 Disk RAID-6 Set = 6 Data + 2 Parity

  Strip Size = 192KB / 6 = 32KB

  EMC E10-001 Student Resource Guide. Module 3: Data Protection - RAID

• Question 64:

  What are the two mechanisms that can be employed to address threats of user identity spoofing?

  A. User authentication and user authorization
  B. Access Control Lists (ACLs) and access control to storage objects
  C. Access control to storage objects and auditing
  D. User authentication and Information Rights Management (IRM)
  A. User authentication and user authorization

• Question 65:

  Which capability does big data analytics provide?

  A. Translating large volumes of data into right decisions
  B. Storing large volumes of data without affecting availability
  C. Reducing the data storage capacity requirement
  D. Performing analytics using traditional tools
  A. Translating large volumes of data into right decisions

• Question 66:

  Which statement describes compute virtualization?

  A. Abstraction of physical hardware that enables multiple operating systems to run concurrently on a single physical machine
  B. Presentation of an application to an end user without any installation, integration, or dependencies on the underlying computing platform
  C. Abstraction of physical storage resources and presenting the logical view of the resources to compute systems
  D. Logical segmentation of physical networks that makes them appear as a single network to compute systems
  A. Abstraction of physical hardware that enables multiple operating systems to run concurrently on a single physical machine

• Question 67:

  Which cache algorithm will optimize a storage array's I/O response time if sequential access is detected?

  A. Flushing
  B. Least recently used
  C. Read ahead
  D. Write-through
  C. Read ahead

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  Read Operation with Cache A prefetch or read-ahead algorithm is used when read requests are sequential. In a sequential read request, a contiguous set of associated blocks is retrieved. Several other blocks that have not yet been requested by the host can be read from the disk and placed into cache in advance. When the host subsequently requests these blocks, the read operations will be read hits. This process significantly improves the response time experienced by the host. The intelligent storage system offers fixed and variable prefetch sizes. In fixed prefetch, the intelligent storage system prefetches a fixed amount of data. It is most suitable when host I/O sizes are uniform. In variable prefetch, the storage system prefetches an amount of data in multiples of the size of the host request. Maximum prefetch limits the number of data blocks that can be prefetched to prevent the disks from being rendered busy with prefetch at the expense of other I/Os.

  EMC E10-001 Student Resource Guide. Module 4: Intelligent Storage System

• Question 68:

  What is a concern of NAS management?

  A. Configuring the system to meet application performance requirements
  B. Configuring the system to meet limited interconnectivity options
  C. Managing the system to integrate multiple block level access ports to the NAS devices
  D. Managing the system to prevent multiple client access to visible volumes
  A. Configuring the system to meet application performance requirements

• Question 69:

  What is an accurate statement about image-based backup in a virtualized environment?

  A. Offloads backup processing from the hypervisor
  B. Backup agents are running on both the VMs and hypervisor
  C. Backup process does not use snapshot technology
  D. Backup agents are running only inside the VM
  A. Offloads backup processing from the hypervisor

• Question 70:

  What is a key advantage of deploying a three-site remote replication solution?

  A. Ensures disaster recovery protection remains available even if the source or remote site failed
  B. Provides the capability to recover data to any point-in-time
  C. Requires very low network bandwidth to perform replication
  D. Enables a consistent near zero RPO in the event of source and remote site failures
  A. Ensures disaster recovery protection remains available even if the source or remote site failed