Article ID: 10819 
Products
SecureStack C3, C2, B3, B2, A2; firmware all 
Goals 
Meaning of the "Fan 0 has failed." or "Fan 1 has failed." reference within syslog, logging buffer, and serial console messages generated upon failure of a fan; for example:<162> OCT 06 10:13:51 10.156.133.245-2 SIM[221852416]: bootos.c(1588) 1173 %%
Fan 0 has failed.
Meaning of the "Fan 1 has failed." or "Fan 2 has failed." reference within current.log messages (
5743) generated upon failure of a fan; for example:<162> MAY 18 17:31:00 10.17.99.21-1 SIM[147737568]: bootos.c(867) 40731958 %%
Fan 2 has failed.
Meaning of the "Fan1-status" and "Fan2-status" references seen in the output of a 'show system' query; for example:Fan1-Status                        Fan2-Status
-----------                        -----------
Installed and Not Operating        Ok
Solution
With C3/C2/B3/B2 firmware x.02.01.0006 and lower, and all A2 firmware:
Syslog 'Fan 0' (current.log 'Fan 1', system 'Fan1') is any of the fans located on the rear of the SecureStack unit near the stacking cables.Syslog 'Fan 1' (current.log 'Fan 2', system 'Fan2') is any of the fans located  on the sides of the unit.
With C3/C2/B3/B2 firmware x.02.02.0009 and higher:
Syslog 'Fan 1' (current.log 'Fan 1', system 'Fan1') is any of the fans located on the rear of the SecureStack unit near the stacking cables.Syslog 'Fan 2' (current.log 'Fan 2', system 'Fan2') is any of the fans located on the sides of the unit.