E20-526 Online Practice Questions and Answers

Correct Answer: B

resxtop is a command to retrieve performance statistics. This command is included in vSphere command line interface (CLI) and is part of the vSphere Management Assistant (vMA), which is an equivalent to esxtop that runs only inside an ESX service console.

Incorrect Answers:

A: esxtop runs only inside an ESX service console.

D: Use the iostat command to report statistics about disk input and output, and to produce measures of throughput, utilization, queue lengths, transaction rates, and service time.

References: www.emc.com/collateral/TechnicalDocument/docu5265.pdf, page 22

Correct Answer: D

Best practice is to use four LUNs for the DATA disk group to allow the host to use simultaneous threads. The REDO and FRA disk groups should use two LUNs each.

References: https://community.emc.com/community/connect/everything_oracle/blog/2016/03/31/bestpractises-of-vblock-on-xtremio-with-oracle-databases-part-i

Correct Answer: D

XtremIO storage is natively thin provisioned, using a small internal block size. This provides fine-grained resolution for the thin provisioned space. All volumes in the system are thin provisioned, meaning that the system consumes capacity only when it is actually needed. XtremIO determines where to place the unique data blocks physically inside the cluster after it calculates their fingerprint IDs. Therefore, it never preallocates or thick-provisions storage space before writing.

References: Introduction to the EMC XtremIO STORAGE ARRAY (April 2015), page 22

Correct Answer: A

XtremIO inline data deduplication and inline data compression services are inline, all the time.

References: https://www.emc.com/collateral/faq/faq-million-dollar-guarantee-rp-2016.pdf

Correct Answer: C

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-FlashScale-Out-Array/p/EMC-XtremIO-Flash-Scale-Out

Correct Answer: D

The workflow for refreshing XtremIO Snapshots, containing Oracle Database files, consists of the following five simple steps:

1.

Shut down the database instances with files in the target Snapshot Set.

2.

Dismount the ASM disk group (or file systems) involved.

3.

Refresh the Snapshot via XtremIO GUI (or CLI or RESTful API).

4.

Mount the ASM disk groups (or file system) involved.

5.

Start the database instances.

This entire workflow is measured in seconds (not minutes).

Incorrect Answers:

A: The refresh command is a powerful tool for test and development environments and for the offline processing use case. With a single command, a snapshot of the production volume or CG is taken and the SCSI face of the volume, which was mapped to the test and development application, is moved to it. This allows the test and development application to work on current data without the need to copy data or to rescan.

References: https://www.emc.com/collateral/white-papers/h14485-xtremio-snapshot-refresh-oracledatabases.pdf, page 8

Correct Answer: A

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-emcxtremio/

Correct Answer: C

Required bandwidth= 100,000 * 8 * 1024 bytes Provided bandwidth between XtremIO arrays with compression over Fiber Channel: 300 * 1024 * 1024 bytes

Required number of RPAs: 100,000 * 8 * 1024 / (300 * 1024 * 1024) = 800,000 / (300 * 1024) = 2.6. Three RPAs would be enough.

Correct Answer: C

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

Correct Answer: BC