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Combining mount command options

Although mount options can be combined arbitrarily, some combinations do not make sense. The following examples provide some common and reasonable mount option combinations.

This is an example for a desktop file system:

# mount -F vxfs -o log,mincache=closesync /dev/dsk/c1t3d0s1 /mnt

This guarantees that when a file is closed, its data is synchronized to disk and cannot be lost. Thus, once an application is exited and its files are closed, no data will be lost even if the system is immediately turned off.

This example is for a temporary file system or restoring from backup:

# mount -F vxfs -o tmplog,convosync=delay,mincache=tmpcache \

/dev/dsk/c1t3d0s1 /mnt

This combination might be used for a temporary file system where performance is more important than absolute data integrity. Any O_SYNC writes are performed as delayed writes and delayed extending writes are not handled specially (which could result in a file that contains garbage if the system crashes at the wrong time). Any file written 30 seconds or so before a crash may contain garbage or be missing if this mount combination is in effect. However, such a file system will do significantly less disk writes than a log file system, and should have significantly better performance, depending on the application.

This example is for data synchronous writes:

# mount -F vxfs -o log,convosync=dsync /dev/dsk/c1t3d0s1 /mnt

This combination can be used to improve the performance of applications that perform O_SYNC writes, but only require data synchronous write semantics. Performance can be significantly improved if the file system is mounted using convosync=dsync without any loss of data integrity.