This is currently in prototype status.
Requires Python and the sg_ses utility, provided by the sg3_utils package.
Debian-based systems might use:
# apt-get install sg3-utils
On RHEL/CentOS systems:
# yum install sg3_utils
FreeNAS 9.10 includes sg_ses as part of the standard image.
Find the SCSI Enclosure Services device corresponding to your SA120. On Linux, this is likely one of the /dev/sg* devices. (Try lsscsi?) On FreeBSD, this is likely /dev/ses* instead.
You can use sg_ses to identify SES devices, e.g.:
# sg_ses /dev/ses0
LSI CORP SAS2X28 0717
…
# sg_ses /dev/ses1
LENOVO ThinkServerSA120 1007
…
Once you've found your SA120, use fancontrol.py to set the fan speed:
# python fancontrol.py /dev/sg0 2
Fan 0 speed: 0
Fan 1 speed: 947
Fan 2 speed: 932
Fan 3 speed: 812
Fan 4 speed: 932
Fan 5 speed: 947
Reading current configuration...
Setting fan 0 to 2
Setting fan 1 to 2
Setting fan 2 to 2
Setting fan 3 to 2
Setting fan 4 to 2
Setting fan 5 to 2
LENOVO ThinkServerSA120 1007
Sending Enclosure Control [0x2] page, with page length=296 bytes
Fan 0 speed: 0
Fan 1 speed: 945
Fan 2 speed: 932
Fan 3 speed: 812
Fan 4 speed: 926
Fan 5 speed: 945