System Administration Guide: Devices and File Systems

Commonly Used UFS Mount Options

The following table describes the commonly used options that you can specify with the mount -o option. If you specify multiple options, separate them with commas (no spaces). For example, -o ro,nosuid.

For a complete list of mount options for each file system type, refer to the specific mount man page (for example, mount_ufs(1M)). For information about mounting ZFS file systems, see zfs(1M).

Table 18–2 Commonly Used -o Mount Options

mount Option 

File System 


bg | fg


If the first mount attempt fails, retries another mount in the background (bg) or in the foreground (fg). This option is safe for non critical vfstab entries. The default is fg.

hard | soft


Specifies the procedure if the server does not respond. The soft option indicates that an error is returned. The hard option indicates that the retry request is continued until the server responds. The default is hard.

intr | nointr


Specifies whether keyboard interrupts are delivered to a hung process while waiting for a response on a hard-mounted file system. The default is intr (interrupts allowed).

largefiles | nolargefiles


Enables you to create files larger than 2 GB. The largefiles option means that a file system mounted with this option might contain files larger than 2 GB. If the nolargefiles option is specified, the file system cannot be mounted on a system that is running an older Solaris version. The default is largefiles.

logging | nologging


Enables or disables logging for the file system. UFS logging is the process of storing transactions (changes that comprise a complete UFS operation) into a log before the transactions are applied to the UFS file system. Logging helps prevent UFS file systems from becoming inconsistent, which means fsck can be bypassed. Bypassing fsck reduces the time to reboot a system if it crashes, or after a system is shut down uncleanly.

The log is allocated from free blocks on the file system, and is sized at about 1 MB per 1 GB of file system space, up to 256 MB. The log size might be larger, up to a maximum of 512 MB, if the file system has a large number of cylinder groups. 

atime | noatime


Suppresses access time updates on files, except when they coincide with updates to the time of the last file status change or the time of the last file modification. For more information, see stat(2). This option reduces disk activity on file systems where access times are unimportant (for example, a Usenet news spool). The default is normal access time (atime) recording.



Changes the mount options associated with an already-mounted file system. This option can generally be used with any option except ro. However, what can be changed with this option depends on the file system type.



Retries the mount operation when it fails. n is the number of times to retry.

ro | rw


Specifies read/write (rw) or read-only (ro). If you do not specify this option, the default is rw. The default option for HSFS is ro.

suid | nosuid


Allows or disallows setuid execution. The default is to allow setuid execution.