Advantage of Random Access Files
In comparison to sequential access files, you may significantly save on the amount of disk space required by the file by using random access. 
With random access, files can be opened for both read/write at the same time. This is a great advantage over using sequential access.

Disadvantage of Random Access Files
You can have wasted space if many fields in the records are left blank or if most of the strings stored in the record are significantly shorter than the length dimensioned for the string.