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Howard Marks
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Seagate Proves Disk Drives Aren't Dead

Traditional disk drives may lack the flash of flash drives, but Seagate shows there's still room for innovation with spinning disks.

We in the tech industry love shiny new things. Once a new technology goes mainstream--say SSDs--we're quick to declare the previous technology dead. The latest technology to join mainframe computers and magnetic tape among the technological walking dead is the venerable disk drive.

However, Seagate is firmly announcing "I'm not dead yet" with the introduction of three new innovative lines of disk drives. These announcements demonstrate the trend of disk vendors segmenting their products for particular use cases. For instance, Seagate has added specialized drives for set-top boxes and hybrids for laptops in addition to desktop, nearline, 10K and 15K RPM drives for the data center.

The most recent additions start with a low-power Terascale drive for nearline applications. The 4TB, 3.5", Terascale uses about two thirds the power (6.5 watts operating) of a typical 7200RPM nearline drive, in part by spinning at a slightly slower 5900 RPM while providing comparable streaming performance. As even nearline storage systems add flash for metadata and caching, the tradeoff of lower random I/O performance seems pretty reasonable.

The second newcomer seems like just a bigger 10K RPM SAS drive; it crams 1.2TB of data in a 2.5" form factor. However, the drive has an interesting RAID Rebuild technology that promises to speed RAID rebuilds by allowing a drive to continue to operate in a degraded state when it can't read data from one surface due to a failure of the head, head amplifier or similar problem.

[A persistent knock against SSDs is their write endurance--or lack of it. Howard Marks explains why you shouldn't worry in "SSDs And The Write Endurance Boogeyman."]

The RAID Rebuild technology sounds a lot like the technology XIO (formerly Xiotech) uses in its ISE to rebuild drives in place. Of course that technology was developed in Seagate's advanced technology group, before that group was sold to XIO to be the core of its ISE arrays. I've asked Seagate for more details, including what RAID controller or software support will be needed, but haven't yet gotten a response.

Finally, Seagate has announced the 600GB Enterprise Turbo, which it claims is the world's fastest enterprise drive. Like the Momentus XT I use in my laptop, the Enterprise Turbo is a hybrid. It uses16GB of eMLC flash as a read cache, and a pinch of SLC to buffer write data in the event of power loss. Seagate claims the hybrid gives three times the random I/O performance of a 15K RPM drive. It appears that IBM will be the Turbo's first OEM customer, packing the little hybrids into its System x and iDataPlex servers.

The advantage of a hybrid drive is that it doesn't require any software development to get the performance boost of a little flash. In a laptop, where there's limited space, or in a server which may not have a RAID controller smart enough to use an SSD as a cache, hybrids can be an easy way to gain performance without giving up capacity.

Some of my storage analyst brethren have been suggesting hybrid drives for larger arrays. There, just as I would rather fix RAID for SSDs, I'd rather see the controller manage its own flash pool(s) rather than chopping up the flash and sticking it on the disk drives.

As if this month's announcements weren't enough for you to believe that disk drives have a future, someone at MYCE.COM got their hands on what looks like a legit copy of Seagate's roadmap. The document in question is six months old and plans may have changed, but it's forecasting 6TB nearline drives for next year.

Sure, SSDs are taking the high-performance end of the storage market away from disks, but we create vast quantities of data every day that don't need sub-millisecond response times. There will be a market for capacity-oriented disk drives for a long time to come.

Howard Marks is founder and chief scientist at Deepstorage LLC, a storage consultancy and independent test lab based in Santa Fe, N.M. and concentrating on storage and data center networking. In more than 25 years of consulting, Marks has designed and implemented storage ... View Full Bio
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