EMC E20-526 Online Practice Questions and Exam Preparation

EMC E20-526 Online Questions & Answers

• Question 21:

  You need to design an Oracle solution for a customer. Which XtremIO best practices should be used in Oracle environments?

  A. Use a 512 byte LUN sector size for databases. Use Eager Zeroed Thick formatting for ESXi
  B. Use a 4 kB LUN sector size for databases. Use Lazy Zeroed Thick formatting for ESXi
  C. Align data on 4 kB boundaries. Use Thin formatting on ESXi
  D. Align data on 4 kB boundaries. Use Lazy Zeroed Thick formatting on ESXi
  A. Use a 512 byte LUN sector size for databases. Use Eager Zeroed Thick formatting for ESXi

  ---

  The default setting for XtremIO volumes is 512e. It is recommended not to alter this in order to use 4K Advanced Format for Oracle Database deployments. There are no performance ramifications when using 512e volumes in conjunction with an Oracle database. On the contrary, 4K Advanced Format is rejected by many elements of the Oracle and Linux operating system stack.

  References: https://www.emc.com/collateral/white-papers/h13497-oracle-best-practices-xtremio-wp.pdf, page 20

• Question 22:

  A Linux administrator is attaching a new RHEL server to their XtremIO storage array. Which configuration setting should be changed?

  A. Enable Logical Volume Manager
  B. Modify the file system block size
  C. Disable HBA Queue Depth
  D. Disable I/O elevators
  B. Modify the file system block size

  ---

  The block size for both Oracle Cluster Registry (OCR) and Cluster Synchronization Services (CSS) voting files are 512 bytes. I/O operations to these file objects are therefore sized as a multiple of 512 bytes. This is of no consequence since the best practice with XtremIO is to create volumes with 512e formatting.

  References: https://www.emc.com/collateral/white-papers/h13497-oracle-best-practices-xtremio-wp.pdf , page 22

• Question 23:

  A storage administrator has 20 TB of storage provisioned to their ESXi cluster from a 10 TB XtremIO storage array. The administrator is concerned about running out of physical capacity on the XtremIO.

  Which recommendation will assist the administrator?

  A. Enable VAAI TPSTUN
  B. Increase the compression ratio on the XtremIO
  C. Disable VAAI XCOPY
  D. Thick provisioned eager zero all VM virtual disks
  A. Enable VAAI TPSTUN

  ---

  TPSTUN is a VAAI primitive that enables the array to notify vSphere when a LUN is running out of space due to thin provisioning over-commit. The command causes suspending all virtual machines on that LUN. XtremIO supports this VAAI primitive.

  Incorrect Answers:

  C: The XtremIO features for VAAI support include:

  Clone Blocks/Full Copy/XCOPY

  Used for copying or migrating data within the same physical array (VMware term: HardwareAcceleratedMove).

  On XtremIO, this allows VM cloning to take place almost instantaneously, without affecting user I/O on active VMs.

  D: The XtremIO features for VAAI support include: Zero Blocks/Write Same

  Used for zeroing-out disk regions (VMware term: HardwareAcceleratedInit).

  This feature provides accelerated volume formatting.

  References: https://itzikr.wordpress.com/2015/12/16/host-configuration-for-vmware-vsphere-on-emc-xtremio/

• Question 24:

  Who developed the framework for testing All-Flash arrays that is used in the XtremIO PoC?

  A. EMC
  B. Seagate
  C. Micron
  D. IDC
  D. IDC

  ---

  IDC outlines a criteria some criteria for selecting a testing tool:

  *

  Generate workloads

  *

  Capture results for analysis: Throughput IOPS Latency

  Etc.

  References: http://info.xtremio.com/rs/xtremio/images/IDC_Flash_Array_Test_Guide.pdf

• Question 25:

  A customer has a workload with the following attributes: Generates 250,000 IOPs 100 TB in logical capacity Read/Write ratio of 1:1 Random workload with 8 kB I/O size Deduplication ratio of 2:1 Compression ratio of 2:1

  Which XtremIO solution should be recommended to the customer?

  A. 1×40 TB X-Brick
  B. 2×10 TB X-Brick
  C. 3×20 TB X-Brick
  D. 4×10 TB X-Brick
  C. 3×20 TB X-Brick

  ---

  XtremIO clusters with 60 TB of physical usable flash capacity can now logically support 360 TB or more of capacity at typical 6:1 data reduction (deduplication plus compression) ratios. Here we have a 4:1 reduction ratio, so 25 TB would be enough. The 250,000 IOP requirments indicates that we need at least two Bricks.

  

  References: https://store.emc.com/en-us/Product-Family/EMC-XtremIO-Products/EMC-XtremIO-All-Flash-Scale-Out-Array/p/EMC-XtremIO-Flash-Scale-Out

• Question 26:

  How can REST API commands be run to manage and monitor an XtremIO cluster?

  A. From the REST API CLI built into each X-Brick
  B. From the REST API GUI built into each X-Brick
  C. From a third-party GUI
  D. From the REST API tab in the XMS GUI
  C. From a third-party GUI

  ---

  The XtremIO's RESTful API allows HTTPS-based interface for automation, orchestration, query and provisioning of the system. With the API, third party applications can be used to control and fully administer the array.

  Normally you would access the API using some form of programming/scripting language, such as Python or Perl. However for the purposes of learning or testing concepts there are a number of tools that work better, such as HTTPRrequester and curl.

  *

  Curl is a command-line tool that exists in all Linux distributions, and is available for most other Unix OSes as well as Windows. To use curl to access XtremIO you'll need to pass it a few options, such as the username/password to access

  the array (any valid account on the XtremIO XMS will work), the URL of the API, and potentially a few options such as -k to tell curl not to validate the SSL certificate (presuming you don't have a valid certificate installed), and -s (silent) to stop

  curl displaying it's progress as it downloads the response.

  *

  HTTPRequester is a browser extension that is available for both Chrome and Firefox.

  As with for curl, you'll need to provide a username/password, which is done by clicking on the "Authentication..." box, which adds two boxes below the URL for the username and the password.

  

  References: https://blog.docbert.org/using-the-xtremio-rest-api-part-1/

• Question 27:

  

  As shown in the exhibit, a customer's environment is configured as follows: Dual X-Brick cluster 8 ESXi hosts with 2 HBAs Each ESXi hosts has 8 LUNs Each LUN is visible through 4 paths

  What should be the host queue depth setting per path?

  A. 64
  B. 128
  C. 256
  D. 1024
  C. 256

  ---

  The queue depth is per LUN, and not per initiator. Here there are 64 LUNs, each visible through 4 paths, which would indicate that 256 is a good choice for the queue depth setting.

  Note: As a general advice, for optimal operation with XtremIO storage, consider the following: Set the queue depth to 256.

  References: https://www.emc.com/collateral/white-paper/h14583-wp-best-practice-sql-server-xtremio.pdf

• Question 28:

  Which SCSI instructions are used to build a bitmap of the changes between the first snapshot and subsequent snapshots when RecoverPoint is used with XtremIO?

  A. SCSI Delta
  B. SCSI Transfer
  C. SCSI DIFF
  D. SCSI Update
  C. SCSI DIFF

  ---

  DIFF protocol - A vendor specific SCSI command which RecoverPoint uses to query XtremIO with in order to obtain a bitmap of changes between two snapshot sets. RecoverPoint uses the output of DIFF command to read the actual data and transfer it to the target side.

  References: EMC RECOVERPOINT REPLICATION OF XTREMIO, Understanding the essentials of RecoverPoint Snap-based replication for XtremIO, page 9 https://www.emc.com/collateral/white-papers/h14296-wp-recoverpoint-replicationof-xtremio.pdf

• Question 29:

  You need to design a VDI solution for a customer. Which best practices should be used for VDI environments?

  A. Align data on 4 kB boundaries. Put persona and user data on XtremIO LUNs
  B. Align data on 4 kB boundaries. Allocate multiple XtremIO LUNs to each host
  C. Align data on 8 kB boundaries. Put the master VM image on an XtremIO LUN
  D. Align data on 8 kB boundaries. Put all VDI-related data on one large LUN
  C. Align data on 8 kB boundaries. Put the master VM image on an XtremIO LUN

• Question 30:

  Which values are required to enter a generic workload into the XtremIO Sizing Tool?

  A. Capacity, IOPs, R/W ratio
  B. IOPs, I/O size, bandwidth
  C. IOPs, bandwidth, latency
  D. Bandwidth, I/O size, latency
  C. IOPs, bandwidth, latency

  ---

  IDC outlines a criteria some criteria for selecting a testing tool:

  *

  Generate workloads

  *

  Capture results for analysis: Throughput IOPS Latency

  References: http://emc.co/collateral/technical-documentation/h15280-euc-xendesktop-vsphere-xtremio-sg.pdf, page 87 http://info.xtremio.com/rs/xtremio/images/IDC_Flash_Array_Test_Guide.pdf, page 7