Section 14.11. The File System Flush Daemon

14.11. The File System Flush Daemon

The fsflush process writes modified pages to disk at regular intervals. The fsflush process scans through physical memory looking for dirty pages. When it finds one, it initiates a write (or putpage) operation on that page.

The fsflush process is launched by default every second and looks for pages that have been modified (the modified bit is set in the page structure) more than 30 seconds ago. If a page has been modified, then a page-out is scheduled for that page, but without the free flag so that the page remains in memory. The fsflush daemon flushes both data pages and inodes by default. Table 14.7 describes the parameters that affect the behavior of fsflush.

Table 14.7. Parameters That Affect fsflush

Parameter	Description	Min	Solaris 10 Default
tune_t_fsflushr	This specifies the number of seconds between fsflush scans.	1	1
autoup	Pages older than autoup in seconds are written to disk.	1	30
doiflush	By default, fsflush flushes both inode and data pages. Set to 0 to suppress inode updates.	0	1
dopageflush	This is set to 0 to suppress page flushes.	0	1