RollingCache.ccc performance debugging … under SU3

[nenenui]

To not mix too much stuff together I will try to answer your questions in individual posts.

@mjchernis

What’s the optimal cache size? I have lots of space but still have my cache set to 256GB.

In short …

• I would keep the size you are already using.

@BearsAreCool510 had a dedicated thread to the question of an “optimal size” for the RC … and my answer is over here:

Maximum rolling cache size that doesn't have adverse effects?

I fully agree that the actual impact of a large cache is “hard to say”. Since the question of this thread was about not having “adverse effects” it makes an answer hard, as it is very hard from the outside to truly understand … which wall the sim is running into … at what point … and why. However, one upper limit is very easy to calculate with high certainty. You can find the details of my argument in this post: The core observation was this: The index area of the RC has a fixed size (51…

However, in most cases “highest FPS” is the primary goal.

In your case … @mjchernis … your tradeoff priority seems to be more about: SSD write stress

I did a deep dive about data volumes over here:

RollingCache.ccc performance debugging and tuning … How?

2024.12.31 - v1.2.8.0 - Rolling Cache data volumes during a normal slow sightseeing flight I wanted to start into the new year with a more constructive test in order to investigate those questions: How much data is actually written to the RollingCache.ccc file during a normal 4.5 hour flight? How much impact does the altitude have? How much difference comes from regions with TIN landscape? I should repeat some info about my FS2024 settings, because they do have a significant impact on this Te…

Approx data demand at “Ultra everything” for looks something like this:

• 1 to 2 GB for the active aircraft
• 5 GB for a major international airport … with lots of static “Ultra” aircraft
• 1 GB per 10 minutes … “low and slow” over a TIN area (e.g. LA)
• 0.5 GB per 10 minutes … 70 ktas and low above ground over normal flat landscape (e.g. in Illinois)
• 0.25 GB per 10 minutes … 70 ktas and 2,500 ft above ground over normal flat landscape (e.g. in Illinois)

If I fly faster (e.g. 200 ktas = factor 3) then the volumes naturally do go up. So in the extreme “worst case” I would calculate with 20 GB/h of data downloads.

Today even cheap QLC-NAND SSDs have a write endurance of around 250 TB per TB capacity.

So for a very small 1 TB SSD it means you could fly for 12,500 hours in TIN heavy regions in “all ultra” before you reach the SSD write endurance “warranty”.

Now if you have “lots of space” and do fly over “normal” (and more interesting) landscape than I would guess that you can multiply the hours by 10 to 100 before you hit a SSD write endurance risk area.