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The mincache mode

The mincache mode has the following suboptions:

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 changes to the file are flushed to disk when the file is closed.

To improve performance, most file systems 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 open can lose data. A mincache=closesync mode file system could be approximately 15 percent slower than a standard mode VxFS file system, depending on the workload.

The following describes where to use the mincache modes:

Because the mincache=direct, mincache=unbuffered, and mincache=dsync modes change non-synchronous I/O to synchronous I/O, there can be a substantial degradation in throughput for small to medium size files for most applications. Since the VX_DIRECT and VX_UNBUFFERED advisories do not allow any caching of data, applications that would normally benefit from caching for reads will usually experience less degradation with the mincache=dsync mode. mincache=direct and mincache=unbuffered require significantly less CPU time than buffered I/O.

If performance is more important than data integrity, you can use the mincache=tmpcache mode. The mincache=tmpcache mode disables special delayed extending write handling, trading off less integrity for better performance. Unlike the other mincache modes, tmpcache does not flush the file to disk when it is closed. When the mincache=tmpcache option is used, bad data can appear in a file that was being extended when a crash occurred.