Using All Flash AccelStor arrays in VDI projects

    Virtual desktops (VDI), it would seem, have a huge advantage over the usual personal computers of employees. However, in reality, a very productive and, moreover, expensive “iron” is required in order for the virtual environment to work at an adequate speed and the VDI should not be an irritant in the work activity of the personnel. One of the bottlenecks in the VDI infrastructure is data storage: it depends on its performance whether it is worth contacting this technology or not.




    Why does a company need VDI?


    VDI technology allows you to significantly simplify and automate the management of IT infrastructure of the workplaces of employees of the organization. The difference from traditional workstations and laptops is especially noticeable with a large staff. In addition, VDI is an excellent tool for the safe delivery of employee work tools (the so-called desktop-as-a-service) from any location, which is extremely popular in organizations with high security requirements and / or having an extensive branch network (medicine, banks, education, retail, etc.).


    If the VDI infrastructure is properly deployed, then very soon it will begin to save the company's funds by drastically reducing the cost of maintenance and reducing the points of vulnerability due to the consolidation of IT equipment and software. At the same time, flexibility will increase when new jobs are added, wherever they are.


    Problems Deploying VDI


    Since VDI implies a multitude of users who simultaneously perform their operations in the workplace, the IT infrastructure requires not only high I / O performance, but also ultra-low delays. If “braking” occurs somewhere, it is highly likely that this will cause a negative for users, and they will demand a return to traditional workstations. This means a complete failure of VDI implementation.


    According to IDC reports, the most failed VDI implementations were related to the performance of storage systems that could not provide high-speed I / O for the entire infrastructure. So the choice of storage systems with the required performance is perhaps the most important task when designing VDI. And, it should be noted, one of the most expensive in terms of cost.


    Spindle and hybrid (mechanical disks + flash) storage systems, as practice has shown, are not suitable for large-scale VDI projects, since they are based on the principle of caching I / O requests to reduce delays. But the cache size is not infinite. As soon as it is full, the delays will increase, users will “rebel” and, consider, the project will be bent. In fact, the requirements for latency on the part of VDI are so high that even traditional RAID-based All Flash systems with NVMe or NVRAM caching can not cope with the load.


    In such projects , AccelStor All Flash systems that do not have a cache will be most welcome : all data is written to the SSD immediately after some rearrangement performed on the fly (synchronous recording). Lack of cache means consistency in performance, both in terms of IOPS and throughput, as well as in terms of delays, which, it should be noted, already have very impressive results.


    Flash optimized architecture


    RAID technology was developed in the late 80s of the last century exclusively for the use of traditional spindle disks. And today it is perhaps the most widely and successfully used technology in the field of data storage. But when building All Flash systems using RAID, there are at least two problems:


    • Data is written on the SSD at random locations on the drive.
    • Data is often overwritten.

    All Flash AccelStor systems work in a completely different way, since they are specifically designed for the efficient use of solid-state drives. The basis is the proprietary technology FlexiRemap , which does not use cache and RAID. 10 years of research and more than 45 patents reveal the full potential of flash memory. With the support of the IT giant Toshiba Memory and the best-in-show awards at the Flash Memory Summit 2016, FlexiRemap technology is truly revolutionary.


    Why FlexiRemap ® ?


    Technology FlexiRemap ® got its name just for the redistribution (remap) of data blocks before recording to SSD. The data will be rearranged into sequential chains and written to drives multiple of 4KB, i.e. in the most comfortable SSD mode. Thanks to this approach, you can achieve a sufficiently high performance (up to 700K IOPS for random write, up to 1.1M IOPS for random read + write) without using a cache.


    Most RAID-based storage systems use expensive SAS SSDs, which are necessary to work with two controllers, and, at the same time, utilize their performance by only 10%. FlexiRemap ® in combination with the cluster architecture shared nothing uses cheaper SATA SSD and utilizes their productivity by 90%, which ultimately means a lower total cost of ownership (TCO) and faster return on investment (ROI).


    In addition, we note that SSDs have a predictable aging cycle associated with the amount of information recorded on them. And as opposed to RAID systems that have a huge overhead on write operations, FlexiRemap ® technology writes data only once, thereby increasing the service life of the drives and reducing the same TCO.


    So All Flash AccelStor system FlexiRemap Technology ® are ideal for projects that use intensive I / O and require very low latency. Such as VDI.


    Early return on investment for storage system


    AccelStor provides an unlicensed model for its devices. Those. the customer gets access to all technologies (clones, snapshots, replication, deduplication, etc.) immediately and forever. Moreover, technical support for devices (and of course software) extends over the entire life of the array, and not just within the warranty / warranty extension. So here, too, the TCO can be significantly reduced.



    Using the deduplication algorithm (FlexiDedupe) allows you to reduce data storage space. In application to VDI, we note that for linked clone, the final compression ratio can easily reach 10: 1. As a result, a fully filled array in combination with deduplication and thin provisioning can provide the cost of one active workplace in the region of 30 USD.


    Testing


    All Flash AccelStor NeoSapphireTM systems were tested using the Login VSI package, which is an excellent tool for measuring the performance and scalability of the VDI infrastructure.


    The test used 500 desktops in linked clone mode in VMware Horizon View. All of them were located on the NeoSapphire P710 array (24x SSD, 10G iSCSI, single node, 700K IOPS sustained write) on 5 volumes of 2TB each, plus a separate replica volume. The load was the 8th high density node platform from Supermicro. A couple of separate servers and All Flash (also from AccelStor) an array of VDI infrastructure and test monitoring systems.



    Test Equipment Infrastructure


    Organization of virtual desktops

    The desktops were virtual machines based on Windows 10 Pro (build 1709) with the configuration: 2x vCPU, 3.5GB RAM (100% reserved), 60GB HDD. Two load profiles were made. In terms of Login VSI, they are designated as knowledge and power. The differences are in the degree of influence on computing resources and requirements for input / output.


    Worker Knowledge Power
    Description Well balanced stress load with high consumption of CPU, RAM and IO resources Very heavy load with maximum stress for the system, requiring very large CPU, RAM and IO resources
    Used software Adobe Reader
    Freemind / Java
    Internet Explorer
    MS Excel
    MS Outlook
    MS PowerPoint
    MS Word
    Photo Viewer
    7-ZIP
    Adobe Reader
    Freemind / Java
    Internet Explorer
    MS Excel
    MS Outlook
    MS PowerPoint
    MS Word
    Photo Viewer
    7-ZIP
    Simultaneous installation of several applications
    Note Larger files were used, higher resolution for graphics

    To understand the typical workload in figures, the approximate resource consumption for each profile (percentages relative to the knowledge profile) is also given:


    Worker Apps open CPU usage Disk reads Disk writes Iops Memory vCPU
    Knowledge 5-9 100% 100% 100% 8.5 1.5GB 2 vCPU
    Power 8-12 119% 133% 123% 10.8 2GB 2 vCPU

    Different modes of operation of the VDI infrastructure were tested, each of which exerted a high load on the All Flash array.


    Tests
    • Provisioning – развертывание пула виртуальных машин

    • Booting – загрузка виртуальных машин, эмуляция начала рабочего дня (так называемый boot storm

    • Login VSI full test (Login) – поэтапное увеличение нагрузки в виртуальных машинах с целью достижения пика, когда производительность начнет деградировать из-за нехватки ресурсов (в данном случае стораджа). Пик не был достигнут, All Flash массив способен обеспечить производительность для большего числа рабочих столов даже в конфигурации нагрузки типа power


    • 30 minute steady-state – 30-ти минутный тест на устойчивость с максимальной нагрузкой


    • Power off – выключение пула виртуальных машин
    • Pool Refresh – возврат диска с ОС к первоначальному размеру


    As a result, regardless of the load mode, comfortable response time was maintained inside the virtual machines. That is, in other words, this means that the user would feel comfortable when working with a similar working environment.


    A pool of 500 desktops in Linked Clone mode lead time Average delay
    Provisioning ~ 32 min 0.59ms
    Booting ~ 2 min 0.68ms
    Login VSI full test (Login) 50 min 0.46ms
    30 minute steady-state 30 min 0.56ms
    Power off ~ 7 min 0.45ms
    Pool Refresh ~ 14 min 0.27ms

    Full test results are available on the Login VSI and AccelStor website .


    Conclusion


    When the storage performance really matters and All Flash array operates in the center of VDI infrastructure, systems built on the basis of FlexiRemap Technology ® , will provide the best price / performance ratio. Using an enterprise SATA SSD and a built-in algorithm to increase their service life, coupled with the low latency of the device as a whole, is just what was created for use in large-scale VDI projects.

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