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In addition to the standard mount mode, the vxfs filesystem provides the mincache=closesync and blkclear modes of operation for enhanced data integrity. The default installation sets up mincache=closesync in /etc/vfstab.
The mincache=closesync mode is useful in desktop environments where users are likely to shut off the power on the machine without halting it first. In this mode, any unlogged changes to the file are flushed to disk when the file is closed. There are exceptions to this, however, if your computer has a caching SCSI host adaptor, a caching IDE disk, or a caching disk controller. For details, see ``Data integrity and caching disk controllers''.
To improve performance, most filesystems do not synchronously update data and inode changes to disk. If the system crashes, files that have been updated within the past minute are in danger of losing data. With the mincache=closesync mode, if the system crashes or is switched off, only files that are currently being written can lose data. A mincache=closesync mode filesystem will be approximately 10 percent slower than a standard mode vxfs filesystem, depending on the workload.
The blkclear mode is used in increased data security environments. The blkclear mode guarantees that uninitialized storage never appears in files. The increased integrity is provided by clearing extents on disk when they are allocated within a file. Extending writes are not affected by this mode. A blkclear mode filesystem should be approximately 10 percent slower than a standard mode vxfs filesystem, depending on the workload. . .