Punting this as I am coming to the end of a very long test cycle that started because of Gmans' question on this topic.
First, I guess I should mention that I have been using a Plextor M.2 128GB PCIe 80mm card with Windows 7 x64 installed with Office apps, while a few games have been installed to a HGST 7,200 rpm 6TB SAS 128MB cache HDD and a 1TB WD Velociraptor 10,000 rpm drive. The OS was also cloned to a 1TB Mushkin Reactor SATA III SSD. Additionally, I used a Crucial Adrenaline 50GB SSC (solid state cache) to accelerate the HDDs with the NVELO Dataplex caching software.
Right off it is obvious that the boot times with the M.2 card are about half what they are with the Reactor SATA SSD. I do not consider boot times to be important, because I rarely have to boot. So, if this saves me twenty seconds each day it's not much to talk about.
As you might expect the M.2 device set the pace for all of the other devices. The Reactor was keeping pace in everything beyond the boot process. The real surprise comes from the Dataplex caching which allowed the 7,200 RPM HGST HDD to keep pace with, and even surpass the Velociraptor (similarly cached and in load times with Civ. V) and in some cases match the Reactor (loading 16k images in PS CS6). I believe you might be able to use a low-end HDD and match SSD performance (or very nearly) with the Adrenaline SSD and the Dataplex software.
As to the M.2 card, if you can afford one large enough to house your OS, and then match that with a standard HDD and caching SSD I think you will have a blazing fast system. I believe that very shortly the drive manufacturer's will begin to release kits for that very purpose. SSDs that are large enough for my storage needs are still too costly, so this is the way I will go.
Good stuff, Chalenge. Thanks for posting it!
Storage & the costs per Gb to maintain it should be a concern for those who have a viable purpose for it & SSD's are getting better but can still be expensive & a concern over a HDD so I get that.
Where I was going w/ my testing was strictly performance driven. Where IMO SSD's can help w/ this is not in regards to FPS....CPU, GPU, system mem, display monitors & mobo subsystem performance will determine this, but in the area where a game (but mostly other apps besides a game), whether written well or poorly, or the Windows OS (mostly via the vid card swap file usage but other instances as well) will periodically call for data to be accessed from storage & read into system mem for the game or the OS or the vid card to use or unused\unnecessary data to be paged out of system mem to storage due to either full system mem saturation or the OS deems it unnecessary or the vid card is calling for the rendered frame(s) stored in the swap file created in storage to be flipped to display as the faster this can be done the less chance of interrupt to the flow of the game\app running (CPU & GPU waiting) which can be noted also as a stutter (or a CTD), IOW's the game\app experience is improved. The faster the subsystem this data travels over can help w/ this as well....ie, PCI-E bus vs thru the mobo chipset via SATA III bus.
Now as I understand that AH in particular was written to try to offset this by the game actually calling for data to be "prefetched" directly into system memory in advance before it is needed to try to lessen this effect by--I'm assuming this part but it makes sense to me--utilizing the CPU's wait times when it is not busy processing a thread (this is where & why it makes sense to use devices--NIC's, sound cards, etc--that have their own onboard signal processing capabilities as these devices do not tie up the CPU time processing these signals making more time for the game to use the CPU to operate & prefetch data...mostly texture data as these data packets are fairly large) & this is also where a SSD's speed can help out as the unnecessary texture data has to be paged out of system mem to storage to make room for the new texture data requested to prevent system mem from becoming saturated (fully addressed) causing the game to momentarily "hang" when the OS will then intervene & make room by dong further paging out of deemed unnecessary data to storage to prevent the system from this situation to "protect itself" to ensure there is sufficient memory addressing for the OS (& AH) to operate. This is what I believe Skuzzy is referring to when he says that AH calls for a lot of small writes to storage hence his reluctance to support the usage of an SSD w/ AH in this forum due to the wear induced to the SSD's NAND & subsequently inviting a SSD failure.....not saying that you can't use 1 w/ AH. The advent of TRIM & improving SSD quality & performance is making the risks of using SSD's w/ AH less of a concern--my own testing & usage can attest to this--but should still be taken into account when making decisions on their use......& I get that as well.
Since my setup is all about the performance & storage isn't a concern (I use mem sticks & DVD's to store any media that I deem important to keep....my storage needs are very small & infrequent), so I went the full SSD route to address the total performance realm of computing........& to satisfy the geek that stirs within me........
Since the advent of MS starting w/ Vista having the OS to also perform prefetching on a larger scale, called SuperFetch (which the OS will try to load the system mem fully to address the paging issues as well.....all due to address the slower access time & read\write speeds of a typical HDD using the page file located on it) there will still be instances where a SSD can help an app--& even some games--to run better\smoother (note I didn't say FASTER, this is misunderstood too frequently) as opposed to a HDD in the general sense of operation. Now the gains may be incremental in nature for the costs necessary to gain them, but the gains are there to be had & I have noticed this in my experience. As hardware & software improve, the gains will become less as the issues will be rectified up front & so will cease to be an issue.
What I take from your work here is you have come across & posted a method that can provide the same similar type benefits as using an SSD exclusively, especially a PCI-E SSD, w/ much less exposure to the higher costs per GB & volativity of using SSD's exclusively & IMO that's good stuff to know................. BTW I have shut down the Plextor TurboCache SSD caching software on my PCI-E SSD as I have deemed it to be more overkill for the already noted performance that I'm currently getting out of this SSD w/ the games\apps that I currently use but I know its there to implement if & when the situation changes.............
In the end all this is essentially geek speak & is good reading & discussion & has some practical usage now but to most all this is irrelevant due to the current development cycle time but in time all will be going down these paths at some point, just like all else concerning computer usage.