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HGST Ultrastar C10K1800 Enterprise HDD Review

HGST Ultrastar C10K1800 Enterprise HDD Review
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HGST, a Western Digital company, continues to flex its media cache muscle with its new line of 12Gb/s SAS Ultrastar C10K1800 10K HDDs. HGST upgraded the new drives to a dual-port 12Gb/s SAS connection and also added it to its previous generation 10K HDDs. HGST designed the C10K1800 to satisfy the needs of mission-critical Tier 1 server and storage environments, such as online transaction processing (OLTP), high performance computing (HPC) and databases, among others.

The 512e models are available in capacities of 300, 600, 900GB and 1.2TB, and the 512n/4Kn models provide the same capacity points but add a 450GB and beefy 1.8TB model. The 50 percent boost in capacity up to 1.8TB means the C10K1800 competes directly with the Seagate 10K v8 series because they are the only two high-density 10K offerings. Toshiba has yet to come forward with a new high-density model.

Hard disk drives are precision instruments, but the inherent limitations of the mechanical platform lead to less differentiation between competing products -- unless a vendor brings a special capability to the table. "Incremental advance" was the name of the game in the HDD industry for the last decade. PMR technology provided a solid base for the slow advances in density and performance, and the lack of a serious competitive threat lulled the HDD industry into a slow but sure cadence of innovation. The explosion of SSDs into the data center changed the paradigm forever, and now HDDs have to compete with faster, denser and more efficient SSDs. In response, the vendors have been moving to offer radically new attributes in a relatively short amount of time, especially when measured in HDD dog years. 

HGST's disk-based media cache technology fits that bill, and the company is offering the feature in all of its enterprise performance products -- and even includes the technology in its high-capacity 7200-RPM helium offerings (and to great effect). Media cache ingests incoming write data and aggregates it in the 128MB DRAM cache, thus effectively multiplying the queue depth of the workload before it is passed down to the platters. The drives feature an average latency of 2.85ms and a sustained transfer rate of 146 to 247 from inner to outer tracks for the 4Kn and 512e models.

Caching data in the HDD's volatile DRAM is usually taboo because it conjures up the possibility of data loss during a host power-loss event. However, HGST's implementation actually improves data integrity and reliability during power loss because it holds a copy of the cached data on a constrained section of the platter. We have a more detailed deep-dive of the tech in our C15K600 evaluation for those interested in the nuts-and-bolts of the technology.

The net effect of media caching is unprecedented HDD random write performance (even the 8TB HDDs feature amazing performance), but without the risks usually associated with caching technologies. The Ultrastar C10K1800 brings a 2.5x boost in random write performance due to media cache technology, and provides a 23 percent increase in sequential speed due to other advances. Seek times range from 3.3-3.7/3.8-4.4 ms read/write based upon the capacity of the drive.

There are going to be inevitable comparisons to HGST's media caching and Seagate's TurboBoost SSHD (Solid State Hard Drive) technology (which uses a NAND flash to cache frequently accessed data). In practice, media cache and SSHDs are two fundamentally different approaches to boosting application performance; media cache accelerates incoming random write data and Seagate's SSHDs caches the outgoing read data.

SSHDs intelligently identify hot data (frequently accessed) and promote a copy of it to a NAND cache, which accelerates performance. The portion of NAND cache is relatively small, usually from 2.6 percent to 5 percent of the overall capacity. Small amounts of intelligently selected cached data have a huge impact on performance, but there is no avoiding the fact that there is a limited amount of cache. We have a technical breakdown of how TurboBoost technology works, and how to extract the best performance from the platform.

HGST's media cache technology aggregates random data during ingest operations. There is no limitation on how long, or how much, random write data is accelerated. The technology applies to the full LBA range of the drive, and we have verified that the drive provides uninterrupted performance in 100 percent/mixed random write workloads even after we subjected the drive to a sustained random write workload that spanned several days.

The C10K1800 features 7 percent lower power draw in comparison to its predecessor. Active power draw spans from 5.7 to 7.4 watts and idle power consumption ranges from 3.9 to 5.1 W. The increased random workload performance from the media cache also fuels an impressive IOPS-to-watt ratio, which we measure extensively in our test regimen.

The drive uses LDPC error detection and offers a 1 sector per 10^16 error rate, an impressive 2-million-hour MTBF and comes with an industry-standard five-year warranty. The C10K1800 offers a wide range of security options, such as Instant Secure Erase (ISE), Trusted Computing Group (TCG) enterprise, SCC-compliant Self-Encrypting Drives (SED) and TCG enterprise SED with FIPS 140-2 certification, level 2.

We have seen the potent performance of HGSTs media-cache-enabled HDDs in both 7,200 and 15,000-RPM varieties; let's see how the technology pans out in the company's newest Ultrastar 10K product.

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