Home / server / Questions / 1057753
In Process
Swivel
Asked: 2021-03-21 23:16:40 +0800 CST

Using two SSDs for Hot-Warm-Cold Caching a HDD on Linux

  • 772

I currently have a debian-based Linux system that I'd like to optimize heavily. This machine has three different drives: An SLC SSD, a QLC SSD, and a 4TB HDD. I wanted to know if it was possible to create a multi-tier caching solution that leverages both of the SSDs for caching at different levels.

My utopian structure is this:

  • SLC SSD (fastest, good-reliability): Hot Cache for files that are written to and read often
  • QLC SSD (fast, OK-reliability): Warm Cache for (potentially larger) files that are written to and read from less often
  • HDD (slow, high-reliability): Cold Storage for files that aren't written to or read often

Unfortunately, I haven't found much in terms of capabilities for multi-tier caching that allows for this type of configuration in the most common linux utilities I've found for this: lvmcache or bcache.

My question is whether or not it is possible to configure lvmcache or bcache to be leverage these drives in such a way? And, if not, are there solutions out there that enable such a configuration?

lvm cache ssd hdd

1 Answers

  1. No, it is not possible unless you want to experiment with multiple, nested lvmcache/dm-cache devices, which is a complex setup difficult to maintain and debug.

    Do yourself a favour and use the SLC SSD to cache your HDD, while keeping the QLC drive for mostly read only data (ie: root and home volumes)

    • 1