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userwords

How are Sshd different from regular Hdd when they have a solid state c

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Seriously :| cannot fix the title, pfff xD:

How are Sshd different from regular Hdd when they have a solid state cACHE ANYWAY

Is this a marketing buzzword. Because they say, hey Sshd have a solid state nand flash like in Ssd so they cache the most used files and for those files you get Ssd level access time.

But well since long ago one of the marketing wepons of hdd manufacturers was in fact the cache of the disk, so from time to time they came with new models 16mb 32mb 64mb 128mb of solid state cache, and as far as i know all Hdd have that solid state cache.

So either im missing that Sshd have maybe a bigger amount of solid state memmory ( unless i msread the seagate Sshd has 64mb while a regular Hdd Seagate enterprise nas 4tb has 128mb of solid state cache and it is not called an sshd by seagate), or maybe the solid state memory in a Sshd is like the one in Ssd, while on regular Hdd is a different kind of memmory, or finally maybe is how that memmory is built, connected or managed in the disk what it makes the difference.

Soo, whts up, whats the answer, and dont tell me it is 42.

Edited by userwords

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Are you referring to things like the hybrid drives, e.g. Momentus XT? Having owned a couple of those, both a 500GB and 750GB model connected via 6Gbps and now have a Samsung SSD connected via 3Gbps SATA... I'd take the pure SSD anyday!

Where the MomentusXT was good, was boot times, thats about it. I didn't notice much in day to day operation of my computers. Mainly office applications and web browsing. Generally boot times improved by maybe 2x, or pretty close to that.

Moving to pure SSD, it's 2x from that, if not more. General responsiveness from the system is felt with the SSD in just launching apps, and opening large files.

8GB of flash within the hybrid SSHD drives is just not enough IMO. 64 would probably have been a better sweet spot, but then cost would be an issue. Now these days, large capacity SSD drives are not an issue, and the costs keep going down quarter over quarter.

Case in point, I had an OCZ Synapse drive, which was a small SSD drive with some "caching," software. It after loading a kernel driver acted as a caching tier for frequently used data. It worked extremely well IMO. 64GB of that, with the 500GB Momentus XT drive, solved an issue 3+yrs ago where there were no affordable 500GB+ SSD drives.

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I for sure knoww that Sshd are of dubious performance and nowhere near a real ssd. Maybe you get from time to time the same performance for a single file written in their cache but as you say thats only for the very few files written into the cache.

But my question is how is different let say a Sshd with 64mb of solid state cache from a regular Hdd that anyways also may have a 64mb of cache that it is in fact also solid state.

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The HDD cache and Hybrid drive cache are not the same thing. The hybrid will be faster as we've seen in our reviews.

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My impression:

The hybrid drive identifies and stores your most frequently accessed data and keeps it in NAND for quick retrieval, it remains there through power cycles and system resets.

The cache on regular drives is smaller and is used for minimal write caching and read ahead caching, essentially enabling smoother data flow to and from the drive, particularly during higher Q depth reads and writes and allowing NCQ to work. This cache is not persistent and is flushed frequently.

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