[Help] Is it possible to split SSDs between cache and a storage pool?

[rorschach]

When I create a cache on my SSDs, even though I allocate just 512GB of 1847 available (two 1TB drives installed), when I go to create a storage pool for rest of the space on the SSDs, the drives aren't available. Is it possible to split the SSDs between cache and a storage pool? Hate to think of 2TB of SSD storage just allocated to cache.

[Gremlin]

You cannot have cache and storage on the same ssd. You could use one ssd for cache and one for storage if you wish.
Some users use a single ssd for system disk and apps (Volume 1, default). Sometimes this will depend on type of nas and storage options you wish to use

[rorschach]

@Gremlin - thanks for clearing that up. If I'd have known that SSDs have to be either cache or storage but not both, I would have installed a smaller SSD, but at least I can do as you suggest - allocate one for cache and one for storage.

Followup - do you happen to know if there is any advantage/disadvantage to allocating a portion of the SSD (like 512GB) for cache versus just allocating the entire 1TB?

Thanks for the help

[Gremlin]

I don't use cache, but I believe the system will only let you allocate a portion depending on size of volume being cached, RAM available and, of course, actual cache capacity.

[TMzethar]

Unlike HDDs, even if you only utilize part of the SSD capacity, SSDs actually write data evenly across all blocks on the drive, so at least the SSD's lifespan generally remains unaffected.
If you wish to cache more data simultaneously, having more available RAM will allow you to use a larger SSD Hyper Cache capacity. For more details on RAM capacity related to SSD cache availability, please refer to:
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