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Managing File Systems in Oracle® Solaris 11.4

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Updated: November 2020

Supported File Systems

The Oracle Solaris OS supports file systems stored on a locally attached storage media such as, a hard disk and file systems stored on a network. Storing file systems locally or on a network enables the VFS architecture to provide information from kernel.

Disk-Based File Systems

Disk-based file systems enable you to access files stored on a locally attached media such as hard disks, CD-ROMs, or USB devices. Oracle Solaris supports different types of disk-based file systems.


Legacy UNIX file system (based on the BSD Fat Fast File system).


Zettabyte file system (ZFS) is the default disk-based and root file system. The ZFS file system has some features which are not found in any other file system, such as, creating storage pools, snapshots, and using copy-on write semantics. These features are not available in any other file system. For more information about ZFS file system, see Managing ZFS File Systems in Oracle Solaris 11.4.


High Sierra File System (HSFS) is used on CD-ROMs and DVDs. Oracle Solaris supports file systems created according to ECMA-119, ISO 9660:1998 or ISO 9660:1999 with Rock Ridge and Joliet extensions. The extensions provide additional features and attributes to files such as long file names (up to 255 characters), and UNIX permissions and attributes. Due to the nature of the media, a HSFS file system is read only.


PC file system (PCFS), which enables read and write access to data and programs on DOS-formatted disks that are written for DOS-based personal computers.


The Universal Disk Format (UDFS) file system which is the industry-standard format for storing information on the optical media technology called DVD (Digital Versatile Disc or Digital Video Disc).


SAM-QFS is an integrated hierarchical storage manager (HSM) and storage area network (SAN) file system. SAM is a component of HSM storage and archive management. QFS is the SAN scalable high performance file system component. SAM-QFS also has an integrated disk volume management and tape volume management. QFS also has a write once, read many times (WORM) file system capability. QFS can be used independently of SAM when just a file system is needed. SAM requires QFS and cannot be used independently of QFS.

Network-Based File Systems

Network-based file systems can be accessed from a network. Typically, network-based file systems reside on a server, and are accessed by other systems across the network. The different types of network-based file systems are as follows:


Network File System (NFS) is a common resource sharing service in an UNIX environment. With the NFS service, you can provide distributed resources (files or directories) by sharing them from a server and mounting them on multiple clients. Oracle Solaris support versions 2, 3 and 4 of the NFS protocol. For more information, see Managing Network File Systems in Oracle Solaris 11.4.


Server Message Block (SMB) protocol is a resource sharing service used primarily in workgroups or domains of Microsoft Windows systems. With the Oracle SMB service, you can provide distributed resources (files or directories) to Windows and Mac OS systems by sharing them from a server and mounting them on multiple clients. For more information, see Managing SMB File Sharing and Windows Interoperability in Oracle Solaris 11.4.

Virtual File Systems

Virtual file systems are memory-based file systems that provide access to special kernel information and facilities. Most virtual file systems do not use file system disk space. Also, some virtual file systems, such as the temporary file system (TMPFS) use the swap space on a disk. The different types of virtual file system are as follows:


The contract file system (CTFS) is an interface for creating, controlling, and observing contracts. A contract enhances the relationship between a process and a system resource. It provides richer error reporting and means of delaying the removal of a resource.

The service management facility (SMF) uses process contracts (a type of contract) to track the processes, which compose a service. Using process contracts helps SMF to identify service failure even if a part of a multi-process service fails.


The mnttab file system (MNTFS) provides read-only access to the table of mounted file systems for the local system.


The object file system (OBJFS) describes the state of all modules currently loaded by the kernel. This file system is used by debuggers to access information about kernel symbols without accessing the kernel directly.


The sharetab file system (SHAREFS) provides read-only access to the table of shared file systems for the local system.


The process file system (PROCFS) resides in memory and contains a list of active processes, by process number, in the /proc directory. Information in the /proc directory is used by commands such as ps. Debuggers and other development tools can also access the address space of the processes by using the PROCFS calls.


The temporary file system (TMPFS) uses local memory for a file system to read and write. Using TMPFS improves system performance by saving the cost of reading and writing temporary files to a local disk or across the network. For example, temporary files are created when you compile a program. The OS generates disk activity or network activity logs while manipulating these files. Using TMPFS to hold these temporary files significantly increases the speed of create, delete, and data access operations.

Files in TMPFS file systems are not permanent. These files are deleted when the file system is unmounted or when the system is shut down or rebooted.

TMPFS is the default file system type for the /tmp directory in the Oracle Solaris OS. You can copy or move files into or out of the /tmp directory, as you would in a ZFS or UFS file system. The TMPFS file system uses swap space as a temporary backing store.


The loopback file system (LOFS) enables you create a new virtual file system so that you can access files by using an alternative path name. For example, you can create a loopback mount of the root (/) directory on /tmp/newroot. This loopback mount and the entire file system hierarchy appears as if it is duplicated under /tmp/newroot, including any file systems mounted from NFS servers. All files are accessible either with a path name starting from root (/), or with a path name that starts from /tmp/newroot.