how can I add SSD as RAID 1 cache?

Question

I have 2x 3TB hard drive setup as software RAID 1. sometimes, it was painfully slow. How can I add an SSD as its cache? is it possible?

Note : the RAID was where the debian linux inside booted from.

Answer 1

There are hardware RAID controllers that offer this functionality with a dedicated connector for a cache drive.

For a software raid, LVM offers this functionality. You can find a howto here [1] or search for LVM and caching together with your operating system to get a more specific tutorial.

I have no experience with running the OS from INSIDE the LVM while doing this. I only keep the data drives in a RAID system and run the OS from an SSD directly.

[1] https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/6/html/logical_volume_manager_administration/lvm_cache_volume_creation