Hybrid drives for Enterprise storage. Experience using Seagate EXOS

5 min


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

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

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

Tasks of the corporate segment

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

In addition, such resource-intensive areas as multidimensional OLAP (Online Analytical Processing) analytics and real-time transaction processing (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 — intensive data flows with a small block size — requires high system performance.

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

In addition, another factor characteristic of the enterprise segment arises – strict requirements for economic efficiency. It is quite obvious that the acquisition and maintenance of All-Flash arrays can afford far from all corporate structures, so many companies have to yield a little bit in performance, but acquire solutions that are much more profitable at the price. These conditions greatly shift the market focus towards hybrid solutions.

Hybrid Principle or TurboBoost Technology

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

According to IDC, in the EMEA region, hybrid storage systems account for about 45.3% of the market. 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 lower.

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

The current generation of this technology in Seagate goes under the commercial name TurboBoost. For the corporate segment, the company uses TurboBoost technology in the Seagate EXOS drive line, which have improved reliability and an optimal combination of performance and efficiency. The storage collected on the basis of such disks will, according to the final characteristics, correspond to the hybrid configuration, while caching the “hot” data occurs at the drive level and is performed due to the firmware capabilities.

Seagate EXOS drives for local SSD cache use embedded eMLC (Enterpise Multi-Level Cell) NAND-memory with a capacity of 16 GB, which is characterized by a much larger rewriting resource than the MLC consumer segment.

Joint utility

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

Externally, this drive looks like a standard HDD: a metal case of 2.5-inch format with a proprietary label and standard holes for fasteners.

The drive is equipped with a SAS3 12 Gb / s interface that 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 appears to be a single carrier in which the storage space is not divided into areas of HDD and SSD. This eliminates the need to use software SSD cache and simplifies system configuration.

As an application scenario for a turnkey solution, work with a load from typical corporate applications was considered.

The main expected benefit from the storage system being created is work efficiency on mixed loads with a predominance of read operations. Software-defined RAIDIX storage systems are characterized by high performance when working with sequential loads, and Seagate drives with TurboBoost technology help optimize work with random queries.

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

At the same time, the entire system looks attractive in terms of price and performance: low-cost (relatively All-Flash) hybrid drives combine well with the flexibility and cost-effectiveness of software-defined storage, built on standard server hardware.

Performance testing

Testing was carried out using the utility fio v3.1.

The sequence of minute fio tests of 32 threads with a queue depth of 1.
Mixed load: 70% read and 30% write.
Block size from 4k to 1MB.
The load on the zone size of 130 GB.

Server platform AIC HA201-TP (1 pc.)
CPU Intel Xeon E5-2620v2 (2 pcs.)
Ram 128GB
SAS adapter LSI SAS3008
Drives Seagate EXOS 10E24000 (8 pcs.)
Array level RAID 6

Test results

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

Conclusion

TurboBoost drives offer new opportunities for users and storage manufacturers. The use of a local SSD cache significantly improves system performance with an insignificant increase in the cost of purchasing drives.

The tests of Seagate drives in storage systems running RAIDIX showed a confidently high level of performance on a mixed load pattern (70/30), which simulates the approximate requirements of applied tasks in the corporate segment. In this case, indicators were achieved 150 times higher than the limit values ​​of HDD drives. Here it is worth noting that the cost of acquiring storage in 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 HDD
  • Up to 220,000 IOps on 8 drives

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