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Re: Somthing toward a "sticky:" Suggestiion for a configuration discussion for various PC usage patterns

Posted: Tue Apr 14, 2020 3:22 am
by alphamayo
What would generally reduce game loads better - an L1+L2 cache and a large block size, or foregoing the L1 cache to use a smaller block size (which requires much more overhead)? In my case going from 64KB to 4KB block size would be 6.5GB of overhead.
And is L1 cache FIFO based? For example, let's say I use an 8GB L1 cache (I have 32GB RAM) and play one large game. Then I switch to a different large game - does the cache from first game get pushed out immediately or is the caching 'smart' like the L2 cache where it tries to keep 'commonly used' blocks?

Re: Somthing toward a "sticky:" Suggestiion for a configuration discussion for various PC usage patterns

Posted: Tue Apr 14, 2020 9:41 am
by Jaga
Split the difference - use a 16kb block size, and use a L2 to support the L1.

The caches are frequency based, meaning the most heavily used blocks will stay in the cache while those rarely used will get pushed out in favor of more desired/requested blocks. That's why you won't see good hitrate right away, but after several launches and game sessions the hitrate will climb.

New Setup Guidance

Posted: Mon May 18, 2020 1:59 am
by vfreeze31
Hi, I am looking at purchasing some new drives for my Gaming System and wanted some recommendations on hardware and configuration that will give me the best bang for my bucks.

I was thinking about a base of a large HDD (possible Toshiba X300 or WD Black) with capacity around 10TB with potentially 2 NVME drives as L2-Cache (possible 1TB each but undecided on drives but would it be good to have them in RAID or is there some other way to optimize it in the software?) and then have RamDisk as L1-Cache (possibly 4GB to 10 GB as I have 32 GB available).

With regards to the L2-Cache drives, would it be best to go with something like high speed Samsung 970EVO Plus or would it work better with something like the new Optane drives that have a much better random read/write IOP performance?

I know that is a bit of a ramble but hopefully you get the idea of what I am thinking.

And secondly, I wanted to confirm if this can work in a tiered model where I can utilise the total storage capacity and not just the storage capacity of the base device.

Nothing is purchased yet, so nothing set in stone.

For reference, the base of my system is an I9-9900K with 32GB of 3200Mhz RAM so I do not think there would be any issue with CPU or Memory overhead, and the system is primarly used for the purpose of gaming.

Please let me know your thoughts at your convenience, I look forward to understanding how to get the most out of this product.

Re: Somthing toward a "sticky:" Suggestiion for a configuration discussion for various PC usage patterns

Posted: Mon May 18, 2020 7:15 am
by support
vfreeze31 wrote:
Mon May 18, 2020 1:59 am
then have RamDisk as L1-Cache (possibly 4GB to 10 GB as I have 32 GB available).
Why do you use a RAMdisk as L1 cache? Do you just mean RAM?
vfreeze31 wrote:
Mon May 18, 2020 1:59 am
With regards to the L2-Cache drives, would it be best to go with something like high speed Samsung 970EVO Plus or would it work better with something like the new Optane drives that have a much better random read/write IOP performance?
L2 cache performance follows the L2 device. If your budget is enough, then just choose the better device as L2 cache.
vfreeze31 wrote:
Mon May 18, 2020 1:59 am
And secondly, I wanted to confirm if this can work in a tiered model where I can utilise the total storage capacity and not just the storage capacity of the base device.
No, I don't think so. Cache is designed for accelerating target storage devices by storing a copy of data from source disks. It is not designed to extend the storage capacity.

Re: Somthing toward a "sticky:" Suggestiion for a configuration discussion for various PC usage patterns

Posted: Mon May 18, 2020 7:27 am
by vfreeze31
Hi, thank you for your prompt reply.
support wrote:
Mon May 18, 2020 7:15 am
Why do you use a RAMdisk as L1 cache? Do you just mean RAM?
Yes, I was just referring to RAM being used for the L1-Cache.
support wrote:
Mon May 18, 2020 7:15 am
L2 cache performance follows the L2 device. If your budget is enough, then just choose the better device as L2 cache.
My budget is flexible enough for either but I was trying to get your opinion on which one would work better. The Optane has higher IOPS and lower latency but the Samsung has faster sustained read/write speeds. Which would be better for a cache scenario?

Also, the second part of that question did not get an answer. Would there be any benefit in using 2 drives for L2-Cache and what would the recommended config be?
support wrote:
Mon May 18, 2020 7:15 am
No, I don't think so. Cache is designed for accelerating target storage devices by storing a copy of data from source disks. It is not designed to extend the storage capacity.
That's fine, I can accept the L1 and L2 cache being purely that and not adding to the capacity of the base drive.

If anyone else has some thoughts on this, I would be interested in hearing them. I still have a bit of time before I commit and purchase the hardware.

Re: Somthing toward a "sticky:" Suggestiion for a configuration discussion for various PC usage patterns

Posted: Mon May 18, 2020 7:52 am
by support
vfreeze31 wrote:
Mon May 18, 2020 7:27 am
The Optane has higher IOPS and lower latency but the Samsung has faster sustained read/write speeds. Which would be better for a cache scenario?
For L2 storage device, generally speaking, IOPS and latency are a little bit more important. This is because generally sustained sequential reads/writes occur less than non-continuous reads/writes in L2 cache.
vfreeze31 wrote:
Mon May 18, 2020 7:27 am
Would there be any benefit in using 2 drives for L2-Cache and what would the recommended config be?
PrimoCache only allows one volume for L2 cache. So if you have multiple SSD drives, you can use hard or soft raid to make them into one volume and thus increasing L2 cache size.

Re: Somthing toward a "sticky:" Suggestiion for a configuration discussion for various PC usage patterns

Posted: Tue May 19, 2020 11:25 pm
by vfreeze31
Thank you for your responses. I will probably look at some form of Optane cache drive. Just strange that most of the M.2 form factor Optane drives only use PCIe 3.0 x2 instead of x4.