SSH is Solid State Hybrid. It is a standard HDD with 4GB SSD.
There are drawbacks to the Solid State Hybrid drive I read about.
Lower performance (access time) for non-cached data
If the data being accessed is not in the cache and the drive has spun down, access time will be greatly increased since the platters will need to spin-up.
Lower performance for small disk writes
Flash memory is significantly slower for writing small data, an effect that is amplified by use of journaling file systems.
Slightly Increased cost
Hybrid hard drives are currently slightly more expensive than their non-hybrid counterparts, because of the higher cost of flash memory.
Reduced lifetime
A hard drive, once spinning, suffers almost no wear. A significant proportion of wear arises during the spin-up and spin-down processes. Indeed, the number of spin-ups is often given as the indication of the lifetime of a hard drive.
Increased perceived noise production
A hybrid hard drive, spinning up and down, may make drive noise more noticeable, especially with varying usage conditions (i.e., fans and hard drive spinning up on usage).
Lower recoverability
Hybrid hard drives, based on storage to both a flash component and a hard drive component, and bound to use by a specific OS (i.e., Windows Vista), cannot be recovered after failure using classic hard drive recovery services.