Solaris Advanced Mount Options

The Solaris UFS implementation provides a few special features differentiating it from the previously documented Linux advanced mount options, specifically, Repair Delay, Update access times?, Force direct IO?, Allow large files?, and Enabled logging? are available, while Allow execution of binaries?, Allow device files?, Allow users to mount this filesystem?, File inherit parent GID? and the reserved space options that were available in Linux are not.

Allow user interrupt?

This option configures whether a user will be permitted to interrupt a process that is blocked waiting for a disk operation on this filesystem. This option corresponds to intr and nointr, and defaults to yes (intr).

Repair Delay

Because it is possible for the server to reboot on a failed mount attempt, the system needs a protective mechanism to prevent it from going into a repair/reboot cycle, which might do more harm to an already damaged filesystem. This option specifies the minimum amount of time between repair attempts. If the system reboots within this time frame and attempts to repair the disk a second time within the time specified, it will simply halt. This option correlates to the toosoon mount directive, and is only available in Solaris versions older then 7. It is unnecessary and ignored on later Solaris revisions.

Update access times?

This option specifies whether the access time, or atime, value of a file will be updated when accessed. Immediately means that a files access time will be updated immediately every time the file is accessed. Deferred means the access time will be updated, but only during the course of other filesystem activity. Finally, No means that access time will never be updated on a file. On ordinary filesystems, it is desirable to leave atime enabled. Alternatively, when using a filesystem exclusively for an application that does not require access time updates, like an NNTP news spool or a web cache, disabling atime updates can provide a small performance boost as the number of disk transactions required is reduced. This option correlates to the noatime, and dfratime and nodfratime switches.

Force direct IO?

This option is functionally the same as the Buffer writes to filesystem? described previously. In its simplest terms it disables buffering between processes and the filesystem. For programs that use very large contiguous files without frequent random access, forcing direct I/O can improve overall throughput. This option correlates to the forcedirectio and noforcedirectio. By default, direct I/O is not enabled, and all disk I/O will be buffered.

Allow large files?

Maximum file size on Solaris, as on most operating systems, has throughout its history gone through changes. In simple terms, this option dictates whether a filesystem will permit files over the size of 2GB (currently). Because there are a number of programs, operating systems, and other filesystems that cannot support files larger than 2GB this limit can be imposed to maintain reliable operation between those differing parts. For example, if a filesystem is to be exported via NFS to operating systems that cannot handle large files, it is wise to enforce this limit on the exporting machine as well. This option corresponds to the largefiles and nolargefiles mount switches.

Enabled logging?

Logging, when enabled, stores filesystem transactions in a log before applying the transaction to the filesystem. In other words, before making an I/O transaction permanent, it must successfully complete. The result of this is that in the event of a unclean shutdown of the system, the filesystem will remain in a consistent state, eliminating the necessity of running fsck on the filesystem. This option correlates to the logging and nologging mount switches.

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