Disadvantages of File system over DBMS Most explicit and major disadvantages of file system when compared to database management systems are as follows:
Data Redundancy- The files are created in the file system as and when required by an enterprise over its growth path. So in that case the repetition of information about an entity cannot be avoided. Eg. The addresses of customers will be present in the file maintaining information about customers holding savings account and also the address of the customers will be present in file maintaining the current account. Even when same customers have a saving account and current account his address will be present at two places.
Data Inconsistency: Data redundancy leads to greater problem than just wasting the storage i.e. it may lead to inconsistent data. Same data which has been repeated at several places may not match after it has been updated at some places. For example: Suppose the customer requests to change the address for his account in the Bank and the Program is executed to update the saving bank account file only but his current bank account file is not updated. Afterwards the addresses of the same customer present in saving bank account file and current bank account file will not match. Moreover there will be no way to find out which address is latest out of these two.
Difficulty in Accessing Data: For generating ad hoc reports the programs will not already be present and only options present will to write a new program to generate requested report or to work manually. This is going to take impractical time and will be more expensive. For example: Suppose all of sudden the administrator gets a request to generate a list of all the customers holding the saving banks account who lives in particular locality of the city. Administrator will not have any program already written to generate that list but say he has a program which can generate a list of all the customers holding the savings account. Then he can either provide the information by going thru the list manually to select the customers living in the particular locality or he can write a new program to generate the new list. Both of these ways will take large time which would generally be impractical.
Data Isolation: Since the data files are created at different times and supposedly by different people the structures of different files generally will not match. The data will be scattered in different files for a particular entity. So it will be difficult to obtain appropriate data. For example: Suppose the Address in Saving Account file have fields: Add line1, Add line2,
City, State, Pin while the fields in address of Current account are: House No., Street No.,

Locality, City, State, Pin. Administrator is asked to provide the list of customers living in a particular locality. Providing consolidated list of all the customers will require looking in both files. But they both have different way of storing the address. Writing a program to generate such a list will be difficult.
Integrity Problems: All the consistency constraints have to be applied to database through appropriate checks in the coded programs. This is very difficult when number such constraint is very large. For example: An account should not have balance less than Rs. 500. To enforce this constraint appropriate check should be added in the program which add a record and the program which withdraw from an account. Suppose later on this amount limit is increased then all those check should be updated to avoid inconsistency. These time to time changes in the programs will be great headache for the administrator.
Security and access control: Database should be protected from unauthorized users. Every user should not be allowed to access every data. Since application programs are added to the system For example: The Payroll Personnel in a bank should not be allowed to access accounts information of the customers.
Concurrency Problems: When more than one users are allowed to process the database. If in that environment two or more users try to update a shared data element at about the same time then it may result into inconsistent data. For example: Suppose Balance of an account is Rs. 500. And User A and B try to withdraw Rs 100 and Rs 50 respectively at almost the same time using the Update process. Update: 1. Read the balance amount. 2. Subtract the withdrawn amount from balance. 3. Write updated Balance value. Suppose A performs Step 1 and 2 on the balance amount i.e it reads 500 and subtract 100 from it. But at the same time B withdraws Rs 50 and he performs the Update process and he also reads the balance as 500 subtract 50 and writes back 450. User A will also write his updated Balance amount as 400. They may update the Balance value in any order depending on various reasons concerning to system being used by both of the users. So finally the balance will be either equal to 400 or 450. Both of these values are wrong for the updated balance and so now the balance amount is having inconsistent value forever.