We would like to use NVMes (SAMSUNG MZ1LB1T9HALS-00007) as a cache-tier in a Ceph System (17.2.0). The problem is that the stored data has a lot of small files and if hot-tiering is set to ~70% on the NVMes many slow-ops show up. Therefore, we thought of increasing ​​nr_requests​​ on the NVMes, i.e., the maximum number of read and write requests that can be queued at one time. However, the limit seems to be 1023:
echo "2046" > /sys/block/nvme0n1/queue/nr_requests
bash: echo: write error: Invalid argument
Used System: Kernel 5.15.0-60-generic, Ubuntu 22.04.1 LTS.
Is there a way to avoid this limitation or is the setup per se not a good idea?
