I currently have a 500 GB SSD that I use as cache. I also have an older 128 GB SSD which was used as cache in the past, but currently is collecting dust.

Now, there's this exciting new internal storage. Let's assume a boot partition of 8 GB. I was wondering if it's possible to do the following:

1. Use the 500 GB SSD for internal boot + cache

2. Use the 128 GB SSD for internal boot + cache, mirroring the 500 GB's boot partition (not mirror the entire drive - only mirror the boot partition)

3. Use the leftover 492+120 GB of data for a total of 612 GB of cache (roughly)

4. Specify that 500 GB SSD is used as cache first, and the 128 GB SSD is only written to when the primary cache is full or the 500 GB SSD fails

5. Specify that the OS boots of the 128 GB SSD and falls back to the 500 GB SSD when the primary boot drive fails

What of the above is possible? Thanks!

27 minutes ago, n0stalghia said:

Use the leftover 492+120 GB of data for a total of 612 GB of cache (roughly)

You can create a btrfs single profile pool or zfs stripe to use the space from both devices combined as the data partition for the pool. It's not possible to create two independ data partions for a boot pool.

1 hour ago, JorgeB said:

You can create a btrfs single profile pool or zfs stripe to use the space from both devices combined as the data partition for the pool. It's not possible to create two independ data partions for a boot pool.

I see, so I would have a redundant internal boot drive and a combined 612 GB that would fail if any of the drives fails, correct? Hm, seems almost worth doing, as my cache currently has no redundancy anyway. Thank you for the insight!

2 minutes ago, n0stalghia said:

so I would have a redundant internal boot drive and a combined 612 GB that would fail if any of the drives fails, correct?

Correct, you could also mirror the data partition, but in that case you would only have 120 GB usable.