Hard drive errors but SMART is passing I have a 2012 Mac mini Server running OSx El Capitan. Our server provider has been sending reports about my hard drive failing, telling us we need to replace it as soon as possible before we have data loss. I've run a smartctl scan on my system and have noticed a lot of errors:

ATA Error Count: 3139 (device log contains only the most recent five errors)
    CR = Command Register [HEX]
    FR = Features Register [HEX]
    SC = Sector Count Register [HEX]
    SN = Sector Number Register [HEX]
    CL = Cylinder Low Register [HEX]
    CH = Cylinder High Register [HEX]
    DH = Device/Head Register [HEX]
    DC = Device Command Register [HEX]
    ER = Error register [HEX]
    ST = Status register [HEX]


However I've also noticed that my overall SMART health scan passes:

=== START OF READ SMART DATA SECTION ===
SMART overall-health self-assessment test result: PASSED


Would now be a good time to go ahead and replace my hard drive or am I good to wait for a little while?
Would now be a good time to go ahead and replace my hard drive or am I
  good to wait for a little while?


The answer comes down to your answer to the question "What's your data and time worth?"

The bottom line is that the rotational (mechanical) drive that services your data is at it's end of its useful life. It could go on for another 6 months or last just another 6 hours.  It's impossible to know for sure.  What we do know is that it is starting to fail.

The best course of action (in order of priority) would be the following:


Make a (Time Machine) backup
Upgrade to an SSD or new HDD
Migrate your data from your old drive


I go into detail about the above steps in a similar post. 

It's best to do it when you can schedule your down time as opposed to dealing with a forced down time because the drive invariably failed (and usually at the most inopportune moment).