1. get value of max_pages_per_rpc

1. lctl get_param osc.*.max_pages_per_rpc
   osc.server-OST0000-osc-ffff8800901b9800.max_pages_per_rpc=256

2. set it permanently with the value 1024

1. lctl set_param -P osc.*.max_pages_per_rpc=1024
2. lctl get_param osc.*.max_pages_per_rpc
   osc.server-OST0000-osc-ffff8800901b9800.max_pages_per_rpc=1024

3. remount OSTs and lustre client

4. get the value of max_pages_per_rpc again

1. lctl get_param osc.*.max_pages_per_rpc
   osc.server-OST0000-osc-ffff88062e2a2800.max_pages_per_rpc=256

The value not changed.