each drive should link at the rated speed.
lots of ways to check (probably more than I've listed):
camcontrol (probably most detailed if you have it available):
camcontrol inquiry (SAS)
root@freenas41[~]# camcontrol inquiry /dev/da0
pass0: <HGST HBTAC2DH2SUN3.2T B170> Fixed Direct Access SPC-4 SCSI device
pass0: Serial Number <redacted>
pass0: 1200.000MB/s transfers, Command Queueing Enabled
camcontrol identify (SATA)
root@freenas41[~]# camcontrol identify /dev/ada0
pass21: <INTEL SSDSC2BB080G4 D2010370> ACS-2 ATA SATA 3.x device
pass21: 600.000MB/s transfers (SATA 3.x, UDMA6, PIO 512bytes)
protocol ACS-2 ATA SATA 3.x
device model INTEL SSDSC2BB080G4
firmware revision D2010370
serial number <redacted>
boot log should tell you what's going on (to a degree):
dmesg -a | grep -i Gbps
for example:
mpr1: Found device <c01<SspTarg,Direct>,End Device> <12.0Gbps> handle<0x0017> enclosureHandle<0x0001> slot 8
SATA drives on Linux and FreeBSD/TNC
smartctl -a /dev/<mydrive>
should show the SATA speed negotiated.
root@freenas41[~]# smartctl -a /dev/ada0
smartctl 7.1 2019-12-30 r5022 [FreeBSD 12.2-RELEASE-p3 amd64] (local build)
Copyright (C) 2002-19, Bruce Allen, Christian Franke,
www.smartmontools.org
=== START OF INFORMATION SECTION ===
Model Family: Intel 730 and DC S35x0/3610/3700 Series SSDs
Device Model: INTEL SSDSC2BB080G4
Serial Number: <redacted>
LU WWN Device Id: 5 5cd2e4 04c45272b
Firmware Version: D2010370
User Capacity: 80,026,361,856 bytes [80.0 GB]
Sector Sizes: 512 bytes logical, 4096 bytes physical
Rotation Rate: Solid State Device
Form Factor: 2.5 inches
Device is: In smartctl database [for details use: -P show]
ATA Version is: ACS-2 T13/2015-D revision 3
SATA Version is: SATA 2.6, 6.0 Gb/s (current: 6.0 Gb/s)
Local Time is: Mon Mar 8 14:17:53 2021 MST
SMART support is: Available - device has SMART capability.
SMART support is: Enabled
sg_info should (sorry no system handy to check) may also tell you some things.