DTS unveils hard drives with DDR RAM cache

By on September 3, 2007, 7:29 PM
Japanese company DTS is touting a new concept for hybrid hard drives, using standard DDR RAM as an on-drive cache to boost performance instead of the usual combination of NAND flash memory with traditional platter-based storage. The technology is called Mcell, and the company claims it is a much cheaper way to provide some of the benefits of solid state storage.

The Mcell is an interesting beast. In terms of size, it fits in the standard 3.5" form factor, but inside it actually contains a 2.5" 5400rpm hard drive, a stick of 1GB DDR2 RAM, and a special chip from DTS that contains a real-time OS and CPU. Don't let the slow RPM fool you. The combination of the write-through cache and the 2.5" disc should afford much quicker access times than with 3.5" 7200rpm drives.
According to DTS, the drive sees speeds above 110MBps in random read tests for data sizes of 64KB to 512MB. Even though performance will almost certainly drop when using data samples larger that the cache size, the numbers are still impressive as it apparently provides faster access times than many 7,200rpm SATA drives available today. Mcell is currently only available in Japan in 80GB, 120GB, and 160GB sizes, with the 80GB model selling for about $136.

User Comments: 2

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Nirkon said:
good! looking forward to drying this out :)
Rick said:
Assuming it works the way I think it does, I think the drawback here is potential data loss... If a drive abruptly loses power, you've lost yourself whatever you working on - up to 1 GB of cached data that queued to be written. DDR is volatile, meaning it doesn't 'remember' data without a power source. There are some ways to engineer around this (capacitors & backup batteries) but none of these are reliable enough to be considered for such technology and would just be non-elegant hacks, IMHO.I can imagine the choice between DDR and Flash was well thought about when creating 'hybrid' drives and I'm making the [big] assumption here that one of the decisions for choosing a design centered around flash is that flash is non-volatile. This means, during power loss or error, the flash module won't 'forget' the data stored in it. This gives hybrid drives a chance to write cached data and could potentially be a 'safer' technology. However, despite all of this, I don't actually know if flash-based hybrid drives actually attempt to write cached data after a power off or not. But if they do, then what I said might make sense. If they don't, then I guess my argument is invalid. :) Just food for thought.
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