It won’t show the actual IO operations, but you can also use the fuser utility to identify process(es) using the filesystem in any way, even those that don’t cause actual IO, or do IO in ways that can’t be traced back to a particular process (mmap() of files is one, where a file can be mmap()‘d by multiple processes):
Synopsis
/usr/sbin/fuser [-c | -d | -f] [-nu] [-k | -s sig] files
[ [- ] [-c | -d | -f] [-nu] [-k | -s sig] files] ...
Description
The fuser utility displays the process IDs of the processes that are using the files specified as arguments.
Each process ID is followed by a letter code. These letter codes are interpreted as follows. If the process is using the file as
c Indicates that the process is using the file as its current directory.
m Indicates that the process is using a file mapped with mmap(2). See mmap(2) for details.
n Indicates that the process is holding a non-blocking mandatory lock on the file.
o Indicates that the process is using the file as an open file.
r Indicates that the process is using the file as its root directory.
t Indicates that the process is using the file as its text file.
y Indicates that the process is using the file as its controlling terminal.
Example:
Assuming your home directory is on a separate filesystem mounted at /export/home, this will show all processes using files in any manner on that file system, including those processes that aren’t doing any IO but have a current working directory in that filesystem along with processes that have files memory mapped from that file system:
fuser -c /export/home