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SSD Caching options? RAID0 _as_ cache?

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  • SSD
  • Cache
  • Storage
Last response: in Storage
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October 14, 2014 5:19:34 AM

Been a while since I've built much, currently running an old socket 1366 i7 from before Intel started using their caching stuff. Anyway, I'm using a separate (128GB) SSD as a system drive in my current system, and runing over my options for a possible 'next build'.. I'm well and truly over having to manually manage installs between physical drives and caching sounds like a great solution.. benchmarks I've seen suggest that serving cached content is "very nearly" as fast as a dedicated SSD, without the headache. However, I'm wondering..

All the documentation I've seen says Intel's in-firmware solution is limited to 64GB. Is that still the case? With growing software install sizes and falling storage prices, I'm thinking that figure is a bit low, and having a larger persistant cache can only be a good thing? Is it possible to dedicate a larger chunk of drive to cache?

Also wondering about the possibility of running multiple drives in a RAID-0 config to serve as the cache (potentially in front of another RAID 1 or 5 array?) I'm thinking that's possibly getting a little beyond what Intel's firmware solution can provide though.. I've seen reference to VeloSSD as a possibility, wondering if there's anything else out there people could recommend?

Also also, wondering about interface bandwidth in such a setup.. At what sort of point would I need to start being concerned of saturating a SATA 6GB bus?

More about : ssd caching options raid0 cache

a b G Storage
October 14, 2014 6:04:45 AM

I guess the better question is, how much of an actual improvement will you experience on your machine with this unique setup over just a large SSD? I mean, if you open firefox faster than you can move your hand from your mouse to your keyboard to type the URL you want then at what point do you just not care if it's faster?

As an example, my Laptop for work has a 16GB partition as a cache to it's spinning disk and usually well over 50% of the reads on the drive are read from cache, depending on the day and what I use it's upwards of 80%.

A caching RAID controller with a large amount of RAM or a huge SSD cache will already cost you about a grand, but a 1TB SSD will be something like 5 or 6 hundred bucks. So how much faster do you really need it?
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October 14, 2014 6:57:27 AM

Fair call.. I keep forgetting that SSDs have that internal parallelism thing going on and bigger tends to equal more faster anyway. I guess the crux of what I'm looking for is... software installs keep getting bigger (This will, amongst other things, be getting used for gaming, where 50GB+ installs seem to be getting more and more standard).. meantime SSD prices are coming down. 64GB just seems quite constrained, when I could for very little extra cost drop a considerably larger drive in there and theoretically have much more content being held in cache. Intel's SRT thing is still limited to that though, isn't it? Has there been any news on them lifting that by any chance?
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a b G Storage
October 14, 2014 7:19:29 AM

Mic_n said:
Fair call.. I keep forgetting that SSDs have that internal parallelism thing going on and bigger tends to equal more faster anyway. I guess the crux of what I'm looking for is... software installs keep getting bigger (This will, amongst other things, be getting used for gaming, where 50GB+ installs seem to be getting more and more standard).. meantime SSD prices are coming down. 64GB just seems quite constrained, when I could for very little extra cost drop a considerably larger drive in there and theoretically have much more content being held in cache. Intel's SRT thing is still limited to that though, isn't it? Has there been any news on them lifting that by any chance?


I'm not sure if there is even a need. If 64GB of your most commonly accessed stuff is at SSD speed then that's a huge portion of your seeks to things like your MFT and windows files, and your most used applications will all be in the cache.

If you think of a Windows 7 directory. If I look at mine currently it's 23.7GB, but how much of that is really read more than 10 times a day? Maybe 2-5% of it... possibly up to 10% of it? 4.8GB of mine is just the installer directory... why would that ever need to be on an SDD? So instead of making a manual link and moving that data to a spinning disk you can run the SSD as a cache disk and only the most accessed things will be fast.

So if you took something like a 256GB SSD, and 4 2TB spinning disks in a RAID5 you could have 64GB of the SSD as a cache to the spinning disk volume, and 190GB for installing anything you really want to always be on the SSD like your browser and 4-5 of your favorite games. You'd end up with a 6TB machine that boots quick and feels snappy, but doesn't cost thousands of dollars. This would be more than sufficient for a huge number of cases and getting much faster might not even be worth it.

If you are doing something like trying to get live uncompressed 4k video or something then sure you might need some fancy special purpose solution, but in the vast majority of cases something simple would work just as well.

Plus, what are you actually using it for? Most online games have a waiting period when you load in to be sure everyone has a chance to load before games start, does it really matter if you load in 1 second and wait for 29 or load in 3 seconds and wait for 27?




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