RamDisk / SSD question

It's known that a HDD with an SSD cache will have the volume capacity of a HDD with much of the performance at the user-level of an SSD (for most things), per the Seagate 750GB XT drives. I was wondering if the same logic would transfer to a RamCache-based SSD. (ie: an SSD with some RAM for caching commonly used apps). If I were to pursue this, what programs would I need (I'd also most likely upgrade from 16GB to 32GB RAM to have extra space for the cache). And how would I tell the computer how to preserve the programming of "this goes to RAM-cache" after I shut down the computer (since doing so would require rebuilding the RAM-cache each time).

Also, what are the differences between my idea, and having a RAMdisk outright? (Pros and Cons).

Thanks

Jason

 

Windows 7 already does this with a service called SuperFetch. It is intended to use any free RAM to cache the most commonly used programs, so that they load faster after you run them the first time.

This is currently the only implementation that I know of that uses RAM as a read-cache to speed up application load times. I do not believe that you can easily "force" your computer to do this otherwise.

The advantage of relying on SuperFetch (or any caching algorithm) over using a RAMdisk outright is that SuperFetch specifically uses it as a read-cache. A RAMdisk will also be used as a data write target, and will need to be repopulated / refreshed if you shut down your laptop.

If you want to increase read speeds "on the cheap", then just rely on SuperFetch and be done with it. If you want to increase read speeds the "correct" way, then spend the money to get a real SSD. They are inexpensive enough these days to be reasonable purchases ($300 for 240GB)

 

methinks Ken doesn't read sigs too well. (I have SSDs)

SSDs do not play nicely with Superfetch, and I have no paging file, hence why I wanted a RamCache / RamDisk.

 

I saw your signature just fine.

My comments were directed less towards you specifically, and more towards the 100's of other people that might read this thread. In the past 12-18 months, there have been plenty of people who have asked the question of whether their next upgrade for general performance should be 4GB --> 8GB RAM (for better SuperFetch), or HDD --> SSD. And the answer is almost always HDD --> SSD.

For your specific use case, it wouldn't really matter. SSDs are already so fast that your storage system is no longer a bottleneck. Going RAMdisk as a cache would be so far beyond the point of diminishing returns, I'd doubt you'd notice a difference. The only two situations I can think of where a RAMdisk would yield a noticeable practical performance difference over an SSD are for massive numbers of random I/Os (such as in a VM bootup), or with very large sequential write patterns (such as in video editing) where the 375MBps sequential write speed of a modern SSD is actually a bottleneck.

 

Here's a reference to some ramdrive/ssd/hd stuff I've posted in the past. I run heavy I/O first to a Ramdrive, then offload it to an SSD, where it's processed, then archive it finally to HD.

Works very well and is extremely fast.

http://forum.notebookreview.com/sol...ch-fear-writes-ssd-ramdisk-2.html#post7790395

Since SSD is already quite fast, ramdrives really only make sense if you have a LOT of I/O and are tweaking for every bit of performance you can get. Otherwise, probably not worth messing with.

 

The big difference is that HDD/SSD is non-volatile. When using RAMDrive/Cache it has to be repopulated at power up and that initially means read speeds of the SSD.

I'm happy enough with Windows native caching but if you want to experiment you could try a 3rd party tool such as Fancycache.

SSD with Fancycache.


Looks impressive simply because a test file is written before being read so you do not see the slower reads of the SSD. Might be some benefit with deferred writes though.