Should I leave an unallocated area of ​​SSD space equal to the amount of SLC cache in the SSD?

Question

Solid State Drives

Setting up LVM cache on SSD. In the article habr.com/ru/post/492834/, the author suggests not to allocate a part of the SSD space equal to the size of his SLC cache.
Is this true today?
Do you do this in your production configurations?
Thank you.

Answer 1

How do you think it will improve performance?
- If the SLC cache is made in the form of a separate chip (hardly) then it is not taken into account in the total volume of the SSD - the reserve is meaningless
- If SLC caching is performed in the form of a special write mode to the same chip, but to the reserve area - then this area is already is never available to the user, it makes no sense to reserve again
- Finally, if SLC caching is really done in a free user area, then this "cache" will take N * 8 volume, because the cells work in SLC mode instead of TLC - it also makes no sense to reserve N volume.
You need to read the specification in detail, do tests and look at them already. For an enterprise-level SSD, IMHO, you shouldn’t bother with this, the manufacturer took care of everything

Answer 2

the disk will decide better for you. even I, with my conceit in this situation, would rely on the manufacturer's engineers)
inappropriately, my personal opinion

Answer 3

Yes, leaving an unallocated area is a good idea.
But what does the size of the SLC cache have to do with it? In addition, in many disks it is dynamic.
The size of the unallocated area is chosen based on the load, and not equated to the cache. How much continuous recording is expected?
The essence of the unallocated area is that there is always a supply of free cells, when recording, you don’t have to deal with garbage collection, so the speed is stable, it doesn’t matter if TRIM is present.