raid - DL380p G8 SSD cache

I have HP DL380p G8 with smart array P421i.

I would like to use SSD cache for my HDDs RAID 10 volume.
I got know I have to buy a SmartCache license for the array and I found some weird info about the posibble configuration of this cache.

I cannot ask for HPE support because of expiration warranty.

Can I use 2 SSDs in RAID 1 and use this as a cache? Somewhere I found in GEN8 I can use only the RAID 0 for the cache.

If not, how does it act if I use only 1 SSD as cache and it fails, does the data fail or what could happen? Or does it use just a read cache so nothing happens to the data?

My information source:
https://www.hpe.com/us/en/product-catalog/detail/pip.5364342.html#

Thank you.

Garen