|Dell Poweredge 2800 audible alerts|
If you have a "dodgy" drive (predictive failure), AND have it on a H/W RAID controller,The power-on/fault indicator slowly blinks green, amber, and off.
The green light above the power LED is disk activity.
If you have the integerated version of the PERC 4, you will not get audible alerts, for the 4/SC, 4/DC, and 4e/DC, the PERC audible alerts will be different from what you describe, they only change the duty cycle of the tones to indicate different conditions, example: Adegradedarray is one second on, one second off. Failed arraythree seconds on, one second off.
Therefore I suguest that the error is not in your storage subsystem.
The server itself will issue a beep code if it's detecting a problem during POST please review the T/S manual here.
Other things you can do is to review the system event logs in the O/S and look for errors, or use some of the open manage tools like server administrator to view the ESM logs. Look at the bezel and see if it's system status indicator is blinking amber, and the LCD display will be amber and should have an error message.