Flash for everyone. All Flash array from QSAN

    The theme of All Flash systems excites the minds of both users who want to get ultrafast storage, as well as storage system manufacturers seeking to meet the needs of their customers. More and more players are fighting for this tidbit of the cake, offering their storage solutions based on solid-state drives. Taiwanese storage system manufacturer QSAN Technology, which has recently joined the race, has released its All Flash product, XCubeFAS XF2026D, also did not stand aside.

    In general, the idea to use QSAN storage as All Flash is not new. In particular, we already mentioned in our previous review of the XCubeSAN line the ability to staff these vaults exclusively with SSD. Due to the possibility of using third-party drives, you can get quite a budget solution, while possessing good performance. But you always want to get the most out of the available opportunities. Therefore, QSAN refined its storage systems for best performance when working with SSDs and released the flagship product XCubeFAS XF2026D , providing it with the loud slogan “Flash for all”.

    This All Flash array can indeed be described as the most affordable in terms of the cost of ownership, since it retains the proprietary feature of QSAN products in the form of support for third-party drives. Indeed, are there many vendors on the market that allow such liberties? Normal storage systems equipped with SSDs do not count. It's all about specialized solutions aimed at using only SSD.

    At first glance: what's the difference? What is important is the final result. However, the ban on the use of HDD can more fully unleash the potential of solid-state drives (yet the principles of SSD and HDD are completely different) and provide a number of unique possibilities in their own way, for example, advanced monitoring of the physical state of SSD. The considered XCubeFAS XF2026D is just such a storage: the use of HDD in it is completely excluded.

    From the hardware point of view, the XCubeFAS XF2026D is a complete analog of the most powerful storage system in the QSAN line - XCubeSAN XS5226D: 2U chassis with 26 drives, two active controllers based on the Intel Xeon Quad Core D-1500 processor, 2 10GbE iSCSI copper ports on each controller . But, unlike its "regular" fellow, XCubeFAS has an increased memory capacity of up to 32GB and the Cache-2-Flash cache protection module in the package. For other features, refer to our review of the XCubeSAN line . Here we note the key features:

    • A very interesting case 2U26, which adds flexibility in the construction of disk configurations due to additional disk slots compared to competing products
    • Up to 8 ports of Fiber Channel 16G or up to 10 ports of 10GbE iSCSI per controller will not only increase the capacity of communication channels, but in some cases do without the use of expensive FC / 10GbE switches

    The XCubeFAS is expanded with the help of the XCubeDAS expansion shelves , which, like the main device, has a 2U26 form factor. Up to 4 shelves are supported in total, or up to 130 SSDs in a single system. Not the most impressive indicator, but, frankly, at the current rate of growth of capacity of individual drives is quite enough for the vast majority of applications.

    The difference with the XCubeSAN line here lies in the "software". The system firmware has been completely rewritten to take full advantage of SSDs. As a result, much attention is paid to monitoring the status and the SSD recording resource as determining the integrity of all stored data. About each drive, you can get both generalized information (alive and well / replacement is needed), as well as detailed data on the amount of data recorded on it (the depth of the request is up to a year). And according to the resource usage from the drive itself, you can independently configure the thresholds for the degradation of SSD.

    There is also a detailed analysis of the performance of all volumes with the same depth of viewing up to one year using the key parameters of Latency, IOPS, throughput with the ability to upload results to a tabular file for external analysis.
    Routine operations to create / modify pools / volumes / targets at the expense of automation tools are implemented quite well. After all, it is no secret that the high performance of All Flash systems is achieved by maximally parallelizing the input / output streams, which requires the creation of multiple volumes, targets, paths, and so on. So, QSAN offers batch creation / modification of such objects.

    With regard to the organization of data storage in XCubeFAS, widely used pools are currently used, within which SSDs are combined into RAID groups. In addition to standard RAID levels, disks can be combined into so-called RAID EE groups, in which hot spare disks are used not as separate drives, but as a set of blocks evenly distributed among all group members. As a result, backup SSDs are also involved in I / O operations, contributing to the overall performance of the system.

    From the usual data protection functions for modern storage systems, we note support for snapshots, clones and asynchronous replication via iSCSI (including integration with VSS). Moreover, replication is very easy to configure: an administrator just needs to specify in the system interface a replication volume and an address with a login / password of the remote system. The rest will be done automatically, including the necessary settings on the remote array. Despite the simplicity of the actions, there are also advanced settings on the part of the schedule, shaping, fault tolerance and load balancing between channels.

    Of course, performance tests are of considerable interest. Moreover, the comparison with the XCubeSAN XS5226D really suggests itself to find out how the All Flash array differs from the usual storage system.

    Stand description:

    • XCubeFAS XF2026D
      • Memory: 4 x 8GB DIMM
      • Firmware: 1.0.0
      • SAS SSD: 24 x Seagate Nytro 3530, XS3200LE10003, 3.2TB, SAS 12Gb / s
      • Pools: x2 (RAID10, 12 x SSD per pool)
      • Volumes: 4 x 100GB to Pool 1 (Ctrl 1); 4 x 100GB to Pool 2 (Ctrl 2)
    • Hosts running Windows Server 2012 R2, 2pcs. In each:
      • 16Gb FC HBA: QLogic
      • 10GbE iSCSI HBA: Intel X710
    • Vdbench
      • Version: 04.04.07
      • Workers: 2 x 4 (1 Worker to 1 Volume)
      • Outstanding I / Os: 128
      • Xfersize: 4K 64K
      • I / O rates: 10 - 120
      • Reporting Interval: 1 sec
      • Warmup period: 5 sec

    Each host was connected by two links to the array to both controllers via Fiber Channel and iSCSI (a total of 4 links to the host) directly without using switches.

    Used load profiles:

    • 4K Random Read: 100% Read, 128 threads, 0-120% iorate
    • 4K Random Write: 100% Write, 64 threads, 0-120% iorate
    • 64K Sequential Read: 100% Read, 16 threads, 0-120% iorate
    • 64K Sequential Write: 100% Write, 8 threads, 0-120% iorate

    As a result, All Flash gained a significant advantage over conventional storage at read operations (up to 80% with latency within 1ms). On write operations the difference is insignificant. Here we are getting close to the performance bar of systems using classic RAID. To overcome this threshold, you need to completely change the concept of building storage space, as, for example, this is done in the IBM Flashsystem or Purestorage. But against the backdrop of competitors with the "classic" architecture, the QSAN XCubeFAS looks quite good.


    QSAN continues to fill the market with its solutions with an excellent price-performance-quality ratio. For the fast-growing All Flash system segment, he introduced the XCubeFAS model with very decent performance. Of course, it’s a pity that the compression and deduplication functions that are already familiar to the All Flash systems market are not yet available for it. The manufacturer promises to expand the functionality later along with the firmware update. But even without space saving technologies, the QSAN XCubeFAS looks confident with the support of third-party SSDs. We do not forget about the complete absence of licenses and technical support on behalf of the vendor in Russia, including the local stock of spare parts. As a result, we get a completely competitive product of the Enterprise level.
    PS For those who want to "touch" the QSAN system management interface, provided a demo access to their storage systems.

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