Most likely you need to create your own custom check for this.
On the fileserver whenever this is a *nix based system you might would like to check iostat output, specially the %util column (last one), on my test system nothing is going on here.
iostat -dx
Linux 3.10.0-1062.4.3.el7.x86_64 (arrakis) 12/19/2019 _x86_64_ (4 CPU)
Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s avgrq-sz avgqu-sz await r_await w_await svctm %util
vda 0.00 0.00 0.01 0.06 0.38 0.67 27.09 0.00 4.19 2.95 4.46 0.43 0.00
scd0 0.00 0.00 0.00 0.00 0.00 0.00 114.22 0.00 0.89 0.89 0.00 0.67 0.00
dm-0 0.00 0.00 0.01 0.06 0.37 0.64 27.10 0.00 4.81 2.98 5.22 0.50 0.00
dm-1 0.00 0.00 0.00 0.00 0.00 0.00 50.96 0.00 1.06 1.06 0.00 0.95 0.00