Data Lifeguard Diagnostic is not available for Mac but there are plenty of alternatives that runs on macOS with similar functionality. The best Mac alternative is GSmartControl, which is both free and Open Source. If that doesn't suit you, our users have ranked more than 25 alternatives to Data Lifeguard Diagnostic and 17 are available for Mac so hopefully you can find a suitable replacement. Other interesting Mac alternatives to Data Lifeguard Diagnostic are smartmontools (Free, Open Source), Stats (Free, Open Source), iStat Menus (Paid) and Disk Drill (Freemium).
The smartmontools package contains two utility programs (smartctl and smartd) to control and monitor storage systems using the Self-Monitoring, Analysis and Reporting Technology System (SMART) built into most modern ATA and SCSI harddisks.
iStat is a series of system monitor apps. It's available in different versions: iStat Menus, iStat for iOS and iStat Server as a companion application to the iStat for iOS app that lets you remotely monitor your computers (free for Windows and Mac).
Disk Drill is a data recovery software that easily protects your files from accidental deletion with Recovery Vault and recovers lost data from disks. Disk Drill supports most of storage drives, file types and file systems.