While doing a test migration of a rather sizeable database I started by dumping the database out of MySQL into a file using mysqldump. For me it was a pretty simple issue.
It turns out that if mysqldump has any trouble writing the output stream it will generate error 28, so when I ran:
mysqldump -uroot -p dbname > output.sql
It was generating a 3 TB file and the partition I was on didn't have 3 TB of space. So, after filling that hard drive partition to 100% with a partial data dump, it generated the following error:
mysqldump: Got errno 28 on write
Apparently other write errors can cause this such as a lack of write permissions within the destination directory.