EMC E20-526 - Questions & Answers

Proceed with filesystem aging by doing random overwrite cycles.

The volume size must be specified in MB, GB, TB, and not in KB.

Incorrect Answers:
D: Quorum disks on XtremIO
The SAN Volume Controller cluster will select disks that are presented by the XtremIO storage system as quorum disks. To maintain availability for the cluster, ideally each quorum disk should reside on a separate disk subsystem.

The quorum device can be any disk device that is shared between two or more nodes. EMC Symmetrix, VNX series, or XtremIO devices are commonly used for this purpose.

References:
https://vcdx133.com/2014/09/14/emc-xtremio-provisioning-a-lun/

Second write workload IOPS = 2 GB/s divided by 128 kB = 2 x 1,073,741,824 / (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/EMC-XtremIO-All-Flash-Scale-Out-Array/p/EMC-XtremIO-Flash-Scale-Out

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/

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

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

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/best-practises-of-vblock-on-xtremio-with-oracle-databases-part-i

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

The recommended maximum number of paths to storage ports per host is 16 as per the table below.

References:
https://www.emc.com/collateral/white-papers/h14475-wp-xtremio-brocade-best-practices.pdf?isPublic=false,page12

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 pre-allocates or thick-provisions storage space before writing.

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