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Iron Mew

Can a SSHD drive be split into a HDD and a SSD?

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I'm buying a computer with a preinstalled Toshiba MQ02ABF050H hybrid drive. It has a 500GB mechanical hard drive and 8GB of NAND flash storage on board, which it uses to cache data from the hard disk for quicker access.

I'm wondering if the two sides of the drive can be configured as two separate drives, using third-party software or some kind of configurator from Toshiba (I'm just guessing here). I plan on running Linux on this computer, and my usual laptop setup (a fairly slim Antergos install) takes up about 6 gigabytes, which would fit on the NAND with space to spare. This way I could run the OS from fast SSD memory and still have 500 GB of non-cached mechanical storage for user data.

Edited by Iron Mew

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The controller manages the flash, I doubt it's even visible to the UEFI, so probably not?

WD did a combo SSD + HDD at some point a while back but I don't think it sold very well. WD Black2 Dual Drive, I think it was.

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I agree with continuum:  the interface is a single SATA connector, and

that necessarily implies that the host will see only one (1) SATA device.

If I were installing an OS on that drive, I would format the first 20-30 GB

as a dedicated OS partition, then format the rest as a dedicated data partition.

Because the spinning platter rotates at 5,400 rpm, you'll get better performance

if the OS is stored on the outermost tracks:  READ and WRITE speeds are

directly proportional to track circumference, in order to maintain relatively

constant recording density.  That's why HDDs slow down as they fill up:

the innermost tracks are necessarily slower in direct proportion to

their shorter track radius.

 

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Thank you, I suspected as much. This makes the hybrid drive fairly useless to me in its intended placement. I'll probably demote it to a system drive on the backup desktop and put a SSD in the laptop.

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Basically how the SSD part of the SSHD works is twofold.  First, it acts as a write buffer temporarily storing data write operations and queuing them for later writing to the platters.  Then it acts as a commonly accessed sector cache for faster read operations from commonly accessed files such as those used by the OS.  How exactly the drive decides which sectors are stored in the cache will vary by manufacturer, model, firmware, etc. and it's not exactly publically posted anywhere.  But, suffice to say the read cache on the SSD starts out empty and initially will operate around the same speed as a normal HDD.  After some time, it'll begin to mark off blocks of sectors that are being regularly accessed and a duplicate of these sectors will be cached in the SSD side for faster accessing.  It basically learns your behavior.

So as already mentioned, there's no way to separate the SSD portion or even to make the system treat it any differently than a standard HDD.  The hybrid functions are all internal to the drive and completely automatic.

Edited by JaredDM
typo

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