The performance of any file system is heavily dependent on DASD I/O performance. If any channels or DASD volumes are overloaded, then it is possible for excessive I/O waits to occur on that DASD. Performance products such as RMF™ show DASD performance.

zFS modify zfs,query,all operator commands also provide reports that show I/O rates per aggregate, and file system request rates per aggregate and per file system. This information, along with DASD performance information from RMF or performance products similar to RMF can be used to balance I/O among your DASD. For example, you can use the query command output to show the file systems that can be moved to different DASD to achieve a better balance among disks.