how does SSHD acctually works

[Symcy94]

So I'm wondering if I should buy SSHD for my notebbok, since I can't afford large SSD to cover all the data I'm using.
I found some benchmarks on the web about boot time of windows 7:
SSD :30sec
SSHD :45sec
HDD :80sec

so I'm wondering how does that acctually works. It has only 8GB of flash memory, but it can handle with boot time that good. Windows folder have like 20GB or even more, so how can boot be so faster if there only 8GB flash?
So I started thinking, that maybe at boot, disk doesn't need to read whole Windows folder ... but here I come to question again: Witch folders/files need to be on that 8GB flash memory inside SSHD, to improve boot time ^^

So I would appreciate if someone could take some time and explain to me, how does that acctually works, which files needed to be on that flash memory, how big are those files normally that are needed at boot of windows etc.
And finally I'm also asking you to tell me your opinon about SSHD drives. Do you think it's worth to upgrade from HDD to SSHD on notebook?

Feel free to post your comments below

 

[0roo0roo]

http://www.storagereview.com/seagate_desktop_sshd_review

 

[Concillian]

It uses the flash very much like a read cache for RAM... putting most often accessed files there. Unlike RAM cache, the flash cache persists between power cycles, so you can always have often used files in the flash.

It should prefer to cache smaller files, since these are particularly bad for mechanical drives.

Mechanical operations on a HDD take significant time. Multiple small ones take WAY more time than a few big ones. Since sustained throughput is ~1/3-1/2 the speed of the fastest SSD, but random small file performance is 1/1000 or even worse the speed of most SSDs, if you are able to use the flash for small files and the HDD for larger files, there is quite a significant increase in overall throughput.

Since there is less of a penalty to use the HDD for large files, then the flash portion can be pretty small and still be very effective. Like any caching solution, you need to give it a little time to learn what files are best. 2-3 days should see significant speed-up.

For a notebook, if you can't fit everything on an SSD, nor do you have a chassis big enough for two drives like an mSATA SSD and a HDD in the bay, then yes, an SSHD is the best option.