How exactly does an SSHD work?

thepinkanator95

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Jul 28, 2013
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So my laptop has an SSHD on it. I thought it meant that it has a small SSD part on it with a HDD for capacity. If so, how can I find out if my operating system is loaded on the SSD part and move it to the SSD part if it's not?
 

Pinhedd

Distinguished
Moderator


Hi,

What you most like have is a Seagate Momentus XT hybrid hard drive. Calling it an SSHD is a bit misleading. I have two of these in my laptop in RAID-0 and I absolutely love them. Don't get disheartened, they are absolutely amazing.

Seagate's Momentus XT hard disk drives combine a traditional platter based hard disk drive with a sizeable NAND Flash cache (which has grown in size over the years). It's very similar to Intel's Smart Response Technology. Intel's SRT performs the caching in software (which necessitates operating system support), but Seagate performs it entirely on the disk controller (which means that it's OS agnostic).

Intel's SRT and Seagate's Hybrid technology use the same operating principle. The existence of the fast solid state device is hidden from the operating system. The cache controller monitors which sectors of the hard disk are being accessed most often, and stores those sectors in the cache volume instead.
This operation is very apparent when running hard disk latency benchmarks. The first pass will exhibit normal hard disk drive latency (around 8ms to 20ms) but the second or third pass will exhibit solid state drive latency (a few microseconds).

Hybrid hard disks are great for laptops.
 

getochkn

Splendid
Moderator
Normally the drive moves files that are accessed most automatically to the SSD part. There is no separate partitions or anything that you can really do to force certain things to stay on one part or the other.
 

TyrOd

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Aug 16, 2013
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The way it works is all of your data is always on the HDD part and the "hot"(most accessed) data is also cached onto the SSD.
It doesn't move files, it copies the most accessed blocks based on a proprietary caching algorithm.
This is handled by the drive's controller chip and in the background and it is not something you have access to.

 

thepinkanator95

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Jul 28, 2013
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Okay so I have a Lenovo U530 (don't know if this helps) with the main partition (C:) holding 470GB and a random other partition of 30GB holding "Applications" and "drivers". What is that 30GB?
 

getochkn

Splendid
Moderator


Probably recovery partition to reinstall you windows from, and your appications that are preinstalled and your drivers.
 

TyrOd

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Aug 16, 2013
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Yes, this is just the two logical partitions on the SSHD, and has nothing to do with the physical structure which happens transparent to the operating system.

Also for your reference, SSHD typically have between 8 and 16GB of NAND flash, so you shouldn't expect them to accelerate much more than just the core operating system files for faster boot times.
 

Pinhedd

Distinguished
Moderator


Hi,

What you most like have is a Seagate Momentus XT hybrid hard drive. Calling it an SSHD is a bit misleading. I have two of these in my laptop in RAID-0 and I absolutely love them. Don't get disheartened, they are absolutely amazing.

Seagate's Momentus XT hard disk drives combine a traditional platter based hard disk drive with a sizeable NAND Flash cache (which has grown in size over the years). It's very similar to Intel's Smart Response Technology. Intel's SRT performs the caching in software (which necessitates operating system support), but Seagate performs it entirely on the disk controller (which means that it's OS agnostic).

Intel's SRT and Seagate's Hybrid technology use the same operating principle. The existence of the fast solid state device is hidden from the operating system. The cache controller monitors which sectors of the hard disk are being accessed most often, and stores those sectors in the cache volume instead.
This operation is very apparent when running hard disk latency benchmarks. The first pass will exhibit normal hard disk drive latency (around 8ms to 20ms) but the second or third pass will exhibit solid state drive latency (a few microseconds).

Hybrid hard disks are great for laptops.
 

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