Brett Allison - 1 April 2021

The Pure Storage FlashArray is a high performing flash system and delivers excellent performance. However, every controller has limitations, so it’s good to understand the key metrics that describe the health of the system. This blog covers the key metrics driving Pure Storage FlashArrays system performance and health.

Pure Storage FlashArray Key Workload Factors

As with most storage systems, the key workload factors driving the performance of health in Pure Storage FlashArray systems are the I/O Rates, Read to Write Ratio, Fast Writes, and Transfer Sizes. Understanding the nuances of these key metrics enable data administrators to ensure their environment is optimally configured for the Pure systems.

I/O’s Per Second

The I/Os per second is the rate of Input / Output requests that the system is servicing. The ability of the system to service I/Os is dependent on a number of workload factors such as: the read to write ratio, the size of I/O, the sequential vs random nature of the workload, and the locality of reference of the data which contributes to the cache read hit ratio.

Read to Write Ratio

The read to write ratio is important because reads require less work for the storage system as they are often satisfied in one of the cache layers. For reads, the FlashArray examines the metadata to determine if the data resides in DRAM, NVRAM, DirectMemory or on the DirectFlash Modules. Each layer is progressively slower.

(Fast) Writes

Writes are most often classified as fast writes because as soon as they hit DRAM on the receiving node, they are replicated through RDMA to the other node. Once replicated to the other node, the host is sent an acknowledgement that the write has completed.

While writes are fast, there is also a limit on the number of writes that a system can process as the data has to be eventually written to the Direct FlashModules. This means for write intensive workloads there are write burst limitations within the system that can negatively affect performance. For all flash systems it is also important to keep in mind that the system will perform poorly once the flash drives begin to wear out the write capabilities on the SSDs.

Transfer Size

Data blocks are written in 4 to 32k blocks which is well suited for random workloads but often times larger blocks sizes (up to 1 MB) can occur for batch workloads. Block sizes larger than 32 KB will need to be broken down into smaller sizes, and this can affect the latency of the I/Os. The larger transfer size will also affect the throughput as the I/O rate and transfer size determine the maximum throughput. All systems have limitations on throughput due to bandwidth limitations on the chassis and connectivity ports.

Workloads with a locality of reference that can be contained within the capacity of the fastest layer will provide the best performance while workloads with a locality of reference much larger than the DRAM, NVRAM and DirectMemory will reside on the DirectFlash Modules and will take longer to fulfill.

Pure I/O Latency / Response Time

Latency, or response time, is the amount of time it takes for the system to service an I/O request. As described previously, there are several layers within the system, and they all provide low latency as compared with traditional spinning drives. The following table provides the latency and compares it to the relative effective distance from the processor at the speed of light. The further from the processor, the longer the I/O request takes.

Technology Latency Effective Distance from the Processor at the Speed of Light
DRAM 1ns 12 inches
NVRAM 60ns 60 feet
StorageMemory 1000ns 1000 feet
NVMe SSD 7-150 us 1.32 to 28.4 miles

 

How to Optimize Pure Storage FlashArray Performance with End-to-End Visibility

Even with a comprehensive understanding of Pure Storage FlashArray’s key performance metrics, effectively monitoring and managing your Pure storage arrays alongside the rest of your multi-vendor environment requires deeper visibility across your whole system from your VMware through your fabric to your FlashArray.

This includes interpretation of all the key performance metrics:

  • Throughput (factor of I/O rate and Transfer size)
  • Front-end Read Response Time
  • Front-end Write Response Time
  • Front-end Overall Response Time

 

End-to-End View of Pure Storage FlashArray Performance in IntelliMagic Vision

End-to-End View of Pure Storage FlashArray Performance in IntelliMagic Vision

 

IntelliMagic Vision is a multi-vendor SAN infrastructure performance and health monitoring solution that utilizes built-in deep expert knowledge about each of the supported platforms, such as Pure Storage FlashArrays, and artificial-intelligence derived insights to provide a single pane of glass for optimizing and protecting the performance and availability of your entire distributed-system environment.

The image above shows one of the out-of-the-box interactive reports presenting all of your Pure Storage FlashArray key metrics in a single view. By clicking on any of the individual charts in the multi-chart, you drill down to a specific port or volume for quick and seamless root cause analysis.

End-to-End FlashArray Connectivity and Configuration Analysis

IntelliMagic Vision also provides end-to-end visibility for performance and configuration analysis from your hosts through your fabric to your FlashArray so that you can quickly identify the source of a high latency:

Pure Storage FlashArray Health Minicharts view in IntelliMagic Vision

Pure Storage FlashArray Health Minicharts view in IntelliMagic Vision

 

This end-to-end configuration analysis goes several steps further than a typical performance monitor and combines all of the connectivity information of your storage arrays into an interactive top-to-bottom view to streamline configuration error identification and resolution, such as:

  • Zoning Misconfiguration
  • Orphaned Volumes and Ports
  • Masking View Errors
  • Asymmetrical Connectivity

Accurate Capacity and Forecasting

The Pure Storage FlashArray has a number of technologies deployed to reduce the footprint and efficiently use the capacity on the system. IntelliMagic Vision provides insight into how efficiently capacity is being used.  In the following table, IntelliMagic Vision provides the utilized capacity along with the data reduction ratio which is key in understanding how efficiently the system is deduplicating your data.

Pure Storage FlashArray Capacity Overview View in IntelliMagic Vision

 

In addition to showing the key capacity metrics, IntelliMagic Vision helps in planning for future storage requirements through its capacity forecasting views. In the chart below the ‘Time until running out’ is shown in red. When it is above 360 days it is not displayed on the chart.

Capacity Burn Down Rate for Pure Storage

 

Better Pure Storage FlashArray Configuration and Monitoring

Pure Storage FlashArrays, just with any platform, has key nuances related to its key metrics that are crucial to understand to ensure optimal performance and availability. It is worth taking the time to understand how the nuances of Pure Storage FlashArray storage arrays impact your environment as a whole.

IntelliMagic Vision offers complete end-to-end performance, configuration and capacity monitoring and visibility for the Pure Storage FlashArray as well as all of the top storage systems on the market. We apply artificial intelligence to the hardware-provided optimal configuration requirements with your specific workload needs to help you proactively eliminate availability and risks and ensure your environment is optimally configured.

If you are looking for in-depth support of your Pure Storage FlashArrays or need a better way to manage your multi-vendor storage environment, start a free trial of IntelliMagic Vision today.

This article's author

Brett Allison
Director of Technical Services
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