So far, attempts have been made to compromise the capacity of the hard disk and the performance of the flash memory for several years. ‘Storage tier structure’ in enterprise storage that classifies 'hot data' as high-performance tier storage, or 'SSD caching' that uses small capacity SSD as a cache of hard drive, and 'Hybrid HDD' that integrated above two into one drive is representative. Intel also has SSD caching technology called 'SRT (Smart Response Technology)'.
‘Intel Optane Memory,’ which came out with the 200 series chipsets of the Intel 7th Gen Core processors, uses the same name as the SSD product family based on Intel's 3D XPoint memory technology, but its use is different. 'Optane memory' on PC is also a caching technology of hard drive that continues the existing SRT, but it is supported only the chipsets after 200 series and RST with 15.5 version or higher. Moreover, it is worthy of attention that the media used for caching is 'Optane Memory' based on the '3D XPoint' technology.
‘Optane’ in Intel is a product brand that uses ‘3D XPoint’ memory media. The SSD of Optane brand is called ‘Optane SSD’, and the currently presented product is 'Optic SSD DC P4800X'. And this ’Optane memory' represents a technology that improves performance by caching of the existing large capacity hard drives with small capacity modules in PCs. Of course, both use '3D XPoint' technology, which features consistently uniform performance through significantly faster access times and high durability than the existing NAND-based SSD.
Intel's ‘Optane Technology’ is composed of 3D XPoint memory media, Intel's storage controller, interconnect IP and software. 'Optane SSD DC P4800X' for data center, which was revealed first, showed the high responsiveness, IOPS performance, sustainability and durability, and it had been presented with 'Memory Drive Technology’ based on the responsiveness. This enables the expansion of a single memory pool by integrating memory and Optane-Based SSD subsystem in the level of OS middle layer on Xeon-based platforms.
'Optane memory' technology on PCs plays a role similar to that of existing SRTs known as 'SSD caching’, it is a big feature that the media is based on '3D XPoint' and is closely integrated with the 7th Gen Core processor based platform. Considering that nearly 80% of the world’s desktops are used as hard drive-based systems and the biggest obstacle to innovation in user experience on PCs is the performance characteristic of HDDs, this Optane technology is quite convincing technology in the market.
The module of ’Optane memory’, which was introduced as a caching of hard drive on PCs, is composed of a single-sided structure of an M.2 2280 form factor. The operating method is NVMe, and the interface specification is PCIe 3.0 x2, which can expect the bandwidth of maximum 2GB/s. Here, it composes Intel’s NVMe controller and one or two 16GB 20nm 3D Point flash memory, so it has capacity of 16GB for one memory and 32GB for two memories.
According to the specification, it has max sequential read up to 900MB/s and max sequential write up to 145MB/s by 16GB standard, which is hard to compare with the existing NAND-based SSDs. A notable feature might be random read performance reaching 190,000 IOPS, but random write performance falls behind as it is about 35,000 IOPS. On the other hand, 32GB model, which is using two memories, has max sequential read up to 1,350MB/s and sequential write 290MB/s. In random I/O performance, 240,000 IOPS for write and 65,000 IOPS for write, which are almost exactly doubled expect for sequential read.
'Durability' might be a notable point in this Optane memory module. Write endurance of 3D XPoint memory, which is used in the module, is about to reach 182.5TB even in 16GB model that uses only one memory. Of course, 32GB model has the same write endurance. However, compared to the existing NAND-based SATA drives, in capacities and the number of modules, it has endurance of enterprise class, which is extremely high level. MTBF is 1.6 million hours and it carries a 5-year warranty.
To enable Optane memory technology on PCs, 7th Gen Intel Core processor, a 200 series chipset-based motherboard that supports storage configurations based on M.2 sockets higher than B250, and an 'Optane memory' module are needed. Moreover, in software, BIOS update including RAID ROM, higher than Intel Rapid Storage Technology (RST) version 15.5, must be installed on the mainboard, and RST 15.5 or later version must be installed in Windows operating system.
The structure of this Optane memory technology itself is similar to the past Smart Response Technology (SRT). It configures a storage controller in RAID mode, and it composes and uses an array through software internally. In addition, B250 chipset does not support other RAID configurations, but only the storage acceleration technology through Optane memory technology, which allows only for RAID mode. On the other hand, during the installation process of Windows 10, installation of a separate driver was not necessary.
To enable Optane memory technology, the controller settings in the mainboard's storage settings must be changed from AHCI to 'Optane Memory Acceleration' mode. In this case, since the controller mode is changed to RAID, it may not be possible to boot from an operating system that has been installed based on AHCI. After that, turn on the RAID ROM loading module setting and remapping option of Optane module, enable Optane memory technology in RST 15.5 setting of Windows, and reboot to apply the setting.
At this time, even if all the settings are made in BIOS, if the technology is not activated after installation of RST 15.5, caching will not work. When the main drive is replaced without releasing the array configuration, the information of the module and that of the array do not match, so activation becomes impossible. In such a case, it will be solved by completely initializing Optane memory with Diskpart. When turning on the remapping option in BIOS, there is a feature in the test system that it is disappeared from BIOS while appeared on RST.
The systems used in the test were a Core i7-7700k processor, 16GB memory, and ASRock's B250M Pro4 mainboard. The version of BIOS used in the test was version 1.51 which integrated ROM of RST 15.5 version, but now Optane memory is officially supported by 2.00 version. Also, the RST version used in the test was also 126.96.36.1995 alpha, but most mainboard manufacturers are offering RST version 188.8.131.521 or later to users before official sales of the Optane memory.
The test system's storage used SATA 1TB hard drives and 120GB SSDs, and it checked the performance improvements that can be achieved by enabling Optane memory technology. Moreover, it needs to be considered the fact that a completely different result could come out since in 'hybrid' compositions such as Optane memory technology, cached data changes according to usage pattern. However, in the case of Optane memory technology, when learning to select caching data, pre-configuration was carried out with presets in advance.
The test scenarios confirmed the results through repeated tests for each scenario of PCMark8, storage tests, and repeated tests for each scenario of SYSMark 2014 SE, along with the basic performance of the module. And, in case of general caching technology or hybrid drive, it is known that it needs about 3 cycles until reflection of the learning. Therefore, the same test was repeated 3-5 cycles and measured. At this time, it was impressive that Optane memory technology reflected caching before 3 cycles.
In the basic performance and property verification of the module through IOMeter, write performance is unsatisfactory in expectation of memory characteristics and interface. In particular, read performance showed results of higher than SATA SSD while write performance, about 150MB/s, could have been better. The 32GB model has
In order to verify the basic performance and characteristics of the module through IOMeter, sequential read and write performance is somewhat unsatisfactory in expectation of memory characteristics and interface. In particular, the read performance is higher than the SATA SSD, but the write performance is as low as 150MB/s. As the 32GB model has twice the performance for write performance, it is expected to get better results.
In random read and write performance of 4KB, the outstanding reading performance stands out. Especially, as QD4 shows performance of about 170,000 IOPS, the performance in terms of responsiveness will get a high score. In addition, since write performance shows the level from QD4 to nearly peak performance, it can be regarded as a well-matched feature for Optane memory technology's purpose, which is 'improvement responsiveness'. However, a 3:1 random mixed workload of about 32KB blocks is often stuck with low write performance.
Of course, the relatively low write performance presented by module is not likely to be more than a personal inconvenience in the use of Optane memory technology. This is mainly because the focus is on the reading work of small files, which are the weak points of the hard disk. At this time, the part where high reading performance can be obtained even under low load is a part where a pleasant response can be expected in a well-optimized environment.
In the scenario test of PCMark 8, it can be seen that the systems using Optane memory technology consistently show slightly higher results than the systems that do not. The level of performance improvement depends on the proportion of storage in the test. The level of the scenario test performance when using Optane memory technology on the hard drive seems to be useful in some degree between the hard drive and SSD.
In addition, Optane memory technology in PCMark 8 shows a result that could expect a slight improvement in performance not only in combination with hard drives, but also in SATA SSD-based PCs. This seems to be due to the higher read performance of the modules of Optane memory technology than the general SATA based SSD. On the other hand, in loading time tests for each application, Optane memory technology showed a certain performance improvement compared to the hard drive, but showed little difference compared to SSD.
At the results of 'SYSMark 2014 SE' test, which is based on the actual programs, Optane memory technology shows a clear performance improvement in combination with the hard drive, but it shows decreasing performance in combination with SSD. Among the test scenarios, the part where Optane memory technology has the greatest impact is 'Media Creation'. In this part, the combination of hard drive and Optane memory shows a score comparable to SSD.
On the other hand, in 'Data/Financial Analysis', the performance difference between hard drive, SSD and Optane memory technology is clear. When Optane memory technology is combined to SSD, the performance showed degradation since write performance was reflected. Also, in terms of 'responsiveness', compared to hard drive, the combination with Optane memory technology showed nearly double performance improvement, but there is a certain degree of difference with the performance of SSD, and the performance even went down when Optane memory was combined to SSD. At total score, the performance of combination of SSD and Optane memory was lower than that of SSD alone.
'Optane memory technology', which can be used in the 7th Gen Core processor-based platform, features a combination of hardware technology compared to existing SRT technology, which also means it is almost the only way to use '3D XPoint' on PCs. In addition, because of its well-crafted caching algorithms and moderately good capacity, it has the advantage of being able to achieve a more uniform performance improvement over conventional hybrid drives or older technologies.
At present, the biggest competitor of Optane memory technology seems to be 120GB SSD with a capacity that can be used as a minimal system drive. Considering the announced price, users who are familiar with PC will use a suitable SSD and hard drive at the same time so that they can get high performance that can be expected. Of course, this is a part that requires user's knowledge and efforts in the environment setting such as customization of data storage space after installing operating system.
Moreover, Optane memory technology is targeted at ‘general users'. In case of using a large-capacity hard drive and Optane memory technology, a user would be provided a more convenient environment than a combination of a low-capacity SSD and high-capacity hard drive. In particular, at the complete PC products that pre-packaged with operating system level, Optane memory technology will be an attractive way to obtain conveniently improved performance for users.
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