Why don't you store everything in the database, that's what it is made for.
A 'text' field can hold really large amounts of text. And if that isn't enough you can make it a 'longtext'
PS
A 'text' field can hold 65,535 Bytes of text (64 Kš
A 'mediumtext' field can hold 16,777,215 Bytes of text (16 Mš
A 'longtext' field can hold 4,294,967,295 Bytes of text (4 GB !)