CITS2002 Systems Programming  
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Organisation of File Systems, continued

Today, nearly all modern operating systems provide relatively simple file systems consisting of byte-addressable, sequential files.

The basic unit of access, the record from Stallings's taxonomy, is the byte, and access to these is simply keyed using the byte's numeric offset from the beginning of each file (the size of the variable holding this offset will clearly limit a file's extent).

The file-systems of modern operating systems, such as Linux's ext2, ext3, and ext4 systems and the Windows-NT File System (NTFS), support volumes with sizes up to 1 exbibyte (EiB) and files with sizes up to 16 tebibytes (TiB).

 

Operating Systems and Databases

More complex arrangements of data and its access modes, such as using search keys to locate individual fixed-length records, have been "relegated" to being supported by run-time libraries and database packages (see Linux's gdbm information).

In commercial systems, such as for a large eCommerce system, a database management system (DBMS) may store and provide access to database information independent of an operating system's representation of files.

The DBMS manages a whole (physical) disk-drive, or a dedicated partition, and effectively assumes much of the operating system's role in managing access, security, and backup facilities.

 

CITS2002 Systems Programming, Lecture 15, p2, 18th September 2023.