E20-526 Online Practice Questions and Answers

Correct Answer: A

Disable Encryption and Non-Encrypted Models This version [Ver. 4.0.2-65] allows disabling the Data at Rest Encryption (DARE), if desired. Disabling and Enabling is done when the cluster is stopped.

References: https://samshouseblog.com/2015/12/29/new-features-and-changes-in-xtremio-ver-4-0-2-65/

Correct Answer: C

EMC recommended setting for Solaris include that the /etc/system file be modified to include the following parameter:

* Set maximum IO size

set maxphys = 0x400000

This also requires increase of the maximum I/O size for the disk driver. The corresponding entry and file for

this change are different for different Solaris versions, as follows:

For Solaris 10 (SPARC):

File: /kernel/drv/ssd.conf

Setting: ssd_max_xfer_size=0x400000;

For Solaris 10 (x86):

File: /kernel/drv/sd.conf

Setting: sd_max_xfer_size=0x400000;

Etc.

References: EMC Host Connectivity Guide for Oracle Solaris, page 167

https://www.emc.com/collateral/TechnicalDocument/docu5132.pdf

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: C

Choose an EMC XtremIO system and scale out linearly by adding more XtremIO X-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: 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: C

Oracle Database performs I/O on data files in multiples of the database block size (db_block_size), which is 8KB by default. The default Oracle Database block size is optimal on XtremIO. XtremIO supports larger block sizes as well. In the case of multiblock I/O (e.g., table/index scans with access method full), one should tune the Oracle Database initialization parameter db_file_multiblock_read_count to limit the requests to 128KB. Therefore, the formula for db_file_multiblock_read_count is: db_file_multiblock_read_count = 128KB / db_block_size

In our case the block size is 1 MB, so the formula db_file_multiblock_read_count is 1 MB/ 8KB = 1024/8 = 128

References: https://www.emc.com/collateral/white-papers/h13497-oracle-best-practices-xtremio-wp.pdf, page 21

Correct Answer: A

Disk service time T(s) = 32 ms (service time for one I/O).

Response time T(r) is calculated as: T(s) / (1 – Utilization), which here calculates to 32 ms/ (1-0.75) = 128

ms.

References: https://community.emc.com/thread/145100?tstart=0

Correct Answer: BC

Correct Answer: B

XtremIO's snapshot technology is implemented by leveraging the content-aware capabilities of the system (Inline Data Reduction), optimized for SSD media, with a unique metadata tree structure.

XtremIO leverages a proprietary flash-optimized data protection algorithm (XtremIO Data Protection or XDP), which provides performance that is superior to any existing RAID algorithm.

References: Introduction to the EMC XtremIO STORAGE ARRAY (April 2015), page 33