There has been many occasions when I reviewing SharePoint environments when I will see the following “SharePoint Health Analyzer Rule: Drives Running Out of Disk Space” issue:
Calculating Required Disk Space
The description from Microsoft available at also isn’t very helpful. You need to start by calculating the amount of free space on the drives you need. To calculate the amount of free disk space needed use the following equation:
Server RAM Size * 5 = Amount of Free Disk Space Needed + Used Disk Space = Size Needed for Disk Drive
Example: 16 GB * 5 = 80 GB of Free Disk Space Needed + 80 GB Used Disk Space = 160 GB Disk Drive Space
SharePoint Log Disk Space
If the amount of free disk space is lower than the needed free disk space then the helpful (/unhelpful?) SharePoint Health Analyzer Rule will appear.
The part that confused me for the longest time was that my SharePoint installation drive had more than enough room, but I was still receiving the warning. What gives? My SharePoint log files were installed on another drive. Oh yes your log drive must also have the same amount of free disk space as well. I guess the SharePoint Health Analyzer is being overly helpful and trying to save you from disaster.
Calculating SharePoint Log Disk Space
For the SharePoint log drive, take the amount of space wanted for the logs and then add the calculated amount of free disk space needed to it.
(Server RAM Size * 5) + maximum size of log files = Disk Space Needed for SharePoint Log Files
Example: (16 GB * 5) + 50 GB = 130 GB of Disk Space Needed for SharePoint Log files
Restrict SharePoint Log Disk Space
In SharePoint Server, the diagnostics logs can be restricted to a fix size. In Central Administration, click on the “Monitoring” link. On the Monitoring page, click on “Configure diagnostic logging” link. On the Diagnostic Logging, page, scroll to the bottom of the page, click the “Restrict Trace Log disk space usage”, and type in the size of the trace log in GBs. Press the OK button.
In summary, if you want the “SharePoint Health Analyzer Rule: Drives Running Out of Disk Space” message to go away you need 5 times the amount of ram free in disk space. This can include other drives that do not have the SharePoint installation files such as the location of SharePoint log files. As long as your drives have space then you can ignore the warning and rely on other monitoring tools, such as virtual machine monitoring tools or SCOM.