Free Practice Questions for EMC E20-526 Exam

Noting the inefficiencies in VMware’s NMP driver, EMC developed a set of drivers specifically designed to overcome these limitations and improve the performance and reliability of the data passing between an array and a server. EMC developed the PowerPath family of products optimized specifically for Linux, Microsoft Windows, and UNIX Operating Systems as well as PowerPath/VE for VMware vSphere and Microsoft Hyper-V hypervisors.

PowerPath is installed on hosts to provide path failover, load balancing and performance optimization VPLEX engines (or directly to the XtremIO array if VPLEX is not used).

Note: VMware, with the cooperation of its storage partners, developed a Native Multipathing Plug-in (NMP). VMware NMP was designed to distribute the load over all the available paths and provide failover protection in the case of path, port or HBA failure, but it has not been fully optimized to work with the controllers in a storage systems. VMware’s NMP Round Robin policy does not have the intelligence that PowerPath has as PowerPath uses testing and diagnostics to continually monitor an environment to determine the optimal path for queuing requests and will adapt to current conditions.

References:https://www.emc.com/collateral/analyst-reports/emc-taneja-group-powerpath-tb.pdf

Second write workload IOPS = 2 GB/s divided by 128 kB = 2 x1,073,741,824 / (128 x 1,024) = 16384 IOPs.

Total IOPS required would be 150,000, from the first workload, plus 16384, totaling 166384.

A 2 X-Brick cluster provides 300K Read/write IOPS so it would be adequate.

Storage capacity and performance scale linearly, such that two X-Bricks supply twice the IOPS, four X-Bricks supply four times the IOPS, six X-Bricks supply six times the IOPS and eight X-Bricks supply eight times the IOPS of the single X-Brick configuration.

Note: 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/EM C-XtremIO-All-Flash-Scale-Out-Array/p/EMC-XtremIO-Flash-Scale-Out

From the menu bar, the Inventory icon is to be clicked to display the Inventory workspace. This workspace takes the place of the Hardware workspace in earlier versions of the XtremIO GUI. With the All Clusters tab selected, we can see a list of all the hardware elements in the managed clusters.

Note: With time, additional clusters can be added to a deployed XMS. In addition, a cluster can be easily moved from one XMS to another. All management interfaces (GUI/CLI/REST) offer inherent multi-cluster management capabilities. Multiple cluster management is supported from version 4.0 and up.

References:

https://community.emc.com/community/connect/everything_oracle/blog/2015/08/27/xtremio-40-multi-array-management

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

Storage capacity and performance scale linearly, such that two X-Bricks supply twice the IOPS, four X-Bricks supply four times the IOPS, six X-Bricks supply six times the IOPS and eight X-Bricks supply eight times the IOPS of the single X-Brick configuration. However, the latency remains consistently low (less than 1ms) as the system scales out. The sub-millisecond latency is validated by actual test results, and is determined according to the worst-case scenario.

References: Introduction to the EMC XtremIO STORAGE ARRAY (April 2015), page 37

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/

The XMS must access all management ports on the X-Brick Storage Controllers, and must be accessible by any GUI/CLI client host machine.

References: Introduction to the EMC XtremIO STORAGE ARRAY (April 2015), page 48

The VAAI XCOPY I/O size of 256 kB gives the best performance. 4 MB is the default value.

References: https://www.emc.com/collateral/white-papers/h14279-wp-vmware-horizon-xtremio-design-considerations.pdf, page 57

EMC ViPR Controller is a software-defined storage platform that abstracts, pools and automates a data center's underlying physical storage infrastructure. It provides data center administrators with a single control plane for heterogeneous storage systems.

ViPR enables software-defined data centers by providing features including:

* Comprehensive and customizable platform reporting capabilities that include capacity metering, chargeback, and performance monitoring through the included ViPR SolutionPack

References: Introduction to the EMC XtremIO STORAGE ARRAY (April 2015), page 60