Hybrid drives for Enterprise storage. Experience Using Seagate EXOS



    A couple of months ago, the Reydyks company got the opportunity to work with fresh Seagate EXOS drives designed for enterprise-class tasks. Their distinctive feature lies in the hybrid device of the drive - it combines the technology of conventional hard drives (for main storage) and solid-state drives (for caching hot data).

    We already had positive experience with using Seagate hybrid drives as part of our systems - a couple of years ago we implemented a solution for a private data center together with a partner from South Korea. Then, the tests used the Oracle Orion benchmark, and the results were not inferior to All-Flash arrays.

    In this article, we will look at how Seagate EXOS drives with TurboBoost technology are arranged, evaluate their capabilities for the tasks of the corporate segment, and check the performance at mixed load.

    Corporate segment objectives


    There is a more or less stable range of tasks that can be described as data storage tasks in the corporate (or enterprise) segment. They traditionally include: the functioning of CRM applications and ERP systems, the operation of mail and file servers, backup and virtualization operations. From the point of view of storage, the implementation of such functions is characterized by a mixed load stream, with a clear predominance of random requests.

    In addition, resource-intensive areas such as multi-dimensional analytics OLAP (Online Analytical Processing) and transaction processing in real time (OLTP, Online Transaction Processing) are actively developing in the enterprise segment. Their peculiarity lies in the fact that they rely more on read operations than on write operations. The load they create — intense data streams with a small block size — requires high system performance.

    The role of all these functions is growing rapidly. They cease to be auxiliary units in the processes of creating value and pass into the section of key components of the product. For many forms of business, this is becoming an important component in building competitive advantage and market sustainability. In turn, this significantly increases the requirements for the IT infrastructure of companies: technical equipment should ensure maximum throughput and minimum response time. To ensure the necessary performance in such situations, choose All-Flash systems or hybrid storage systems with the function of SSD-caching or tearing.

    In addition, another factor characteristic of the enterprise segment arises - stringent requirements for economic efficiency. It is quite obvious that not all corporate structures can afford the acquisition and maintenance of All-Flash arrays, so many companies have to yield a little less in performance, but purchase solutions that are much more cost-effective. These conditions strongly shift the market focus towards hybrid solutions.

    Hybrid Principle or TurboBoost Technology


    The principle of using hybrid technologies is now well known to a wide audience. He talks about the possibility of using different technologies to obtain additional benefits in the final result. Hybrid storage combines the strengths of solid state drives and classic hard drives. At the output, we get an optimized solution where each component works with its own task: HDD is used to store the bulk of the data, and SSD is used to temporarily store “hot data”.

    According to IDC , in the EMEA region about 45.3% of the market is hybrid storage. Such popularity is determined by the fact that with comparative performance the cost of such systems is significantly lower than that of SSD-based solutions, and the price for each IOps is several orders of magnitude behind.

    The same hybrid principle can be implemented directly at the drive level. Seagate was the first to implement this idea in the form of SSHD (Solid State Hybrid Drive) media. Such discs have gained relative popularity in the consumer market, but they are not so common in the b2b segment.

    Seagate's current generation of this technology comes under the commercial name TurboBoost. For the enterprise segment, the company uses TurboBoost technology in the Seagate EXOS line of drives, which have increased reliability and the optimal combination of performance and efficiency. The storage system assembled on the basis of such disks will correspond to the hybrid configuration according to the final characteristics, while caching of "hot" data occurs at the drive level and is performed due to the firmware capabilities.

    Seagate EXOS drives use the built-in eMLC (Enterpise Multi-Level Cell) 16GB NAND memory for local SSD cache, which is characterized by a significantly larger rewrite resource than the consumer segment MLC.

    Shared utility


    Having got at our disposal 8 Seagate EXOS 10E24000 drives with a capacity of 1.2 TB, we decided to check their performance as part of our system based on RAIDIX 4.7.

    Externally, such a disk looks like a standard HDD: a 2.5-inch format metal case with a company label and standard mounting holes.



    The drive is equipped with a SAS3 12 Gb / s interface, which allows you to work effectively with two storage system controllers. It is also worth noting that this interface has a greater queue depth than SATA3.



    Note that from the point of view of management, such a disk in a storage system seems to be a single medium in which the storage space is not divided into areas of HDD and SSD. This eliminates the need for a software SSD cache and simplifies system configuration.

    As an application scenario for a ready-made solution, work with a load from typical enterprise applications was considered.

    The main expected benefit from the created storage system is the efficiency of work on mixed loads with a predominance of read operations. RAIDIX software-defined storage systems offer high performance for sequential workloads, while Seagate drives with TurboBoost technology help optimize performance with random requests.

    For the selected scenario, it looks like this: the efficiency of working with random load from databases and other applications will be guaranteed by SSD elements, and the specifics of the software will allow maintaining a high processing speed of a sequential load from restoring a database or loading data.

    At the same time, the whole system looks attractive in terms of price and performance: inexpensive (relative to All-Flash) hybrid drives are well combined with the flexibility and cost-effectiveness of software-defined storage built on standard server hardware.

    Performance testing


    Testing was performed using the fio v3.1 utility.

    The sequence of minute fio-tests of 32 streams with queue depth 1.
    Mixed load: 70% read and 30% write.
    Block size from 4k to 1MB.
    The load on the zone size of 130 GB.
    Server platformAIC HA201-TP (1 pc.)
    CPUIntel Xeon E5-2620v2 (2 pcs.)
    RAM128GB
    SAS adapterLSI SAS3008
    DrivesSeagate EXOS 10E24000 (8 pcs.)
    Array levelRAID 6


    Test results










    A RAIDIX 4.7-based system with 8 Seagate EXOS 10e2400 drives shows a total performance of up to 220,000 IOps read / write in 4k block.

    Conclusion


    TurboBoost storage drives open up new possibilities for storage users and manufacturers. Using a local SSD cache significantly improves system performance with a negligible increase in the cost of purchasing drives.

    The tests of Seagate drives in storage under RAIDIX control showed a confidently high level of performance on a mixed load pattern (70/30), which simulates the approximate requirements of application tasks in the corporate segment. At the same time, performance was achieved 150 times higher than the limit values ​​of HDD drives. It is worth noting that the cost of acquiring storage on this configuration is about 60% of the cost of a comparable All-Flash solution.

    Key indicators


    • The annual disk failure rate is less than 0.44%
    • 40% cheaper All-Flash solutions
    • 150 times faster than HDD
    • Up to 220,000 IOps on 8 drives

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