Sync Pin Reads/sec is the frequency of reading data into the file system cache preparatory to writing the data back to disk. ...

Sync Pin Reads/sec is the frequency of reading data into the file system cache preparatory to writing the data back to disk.  Pages read in this fashion are pinned in memory at the completion of the read.  The file system will not regain control until the page is pinned in the file system cache, in particular if the disk must be accessed to retrieve the page.  While pinned, a page's physical address in the file system cache will not be altered.