To secure erase when that option isn't available in Disk Utility. For example, for SSDs. Boot from another disk or recovery mode. Erase the disk encrypted, with a complex key. Fill the disk with zeros. Erase it again, without encryption or with a different key.
Options to fill with zeros
If it is available, use mkfile, otherwise use dd...
mkfile SIZE FILE Example: mkfile 200G File1 dd if=/dev/zero of=FILE bs=BLOCKSIZE count=BLOCKS Example: dd if=/dev/zero of=File1 bs=1024 count=1000000 Warning: don't make bs too small or the process will be very slow.
Warning: mysqli_connect(): MySQL server has gone away in /Library/WebServer/Documents/Owen2/Inc/Log.inc.php on line 8
Warning: mysqli_connect(): Error while reading greeting packet. PID=83149 in /Library/WebServer/Documents/Owen2/Inc/Log.inc.php on line 8
Warning: mysqli_connect(): (HY000/2006): MySQL server has gone away in /Library/WebServer/Documents/Owen2/Inc/Log.inc.php on line 8
Could not connect to MySQL: MySQL server has gone away