Disk Imperfection Detection
If you’ve been using and supporting computers as long as I have, you know that just as computers have gotten faster and cheaper, so too have hard drives gotten bigger and cheaper. But drives have also gotten more reliable—even the inexpensive ones. Nowadays you can get a 250GB hard drive for not much more than $100, and it’s expected to last at least five years. Sure, there are lemons, but if you look at the number of hard drives out there and then consider how many people have actually had a drive fail mechanically , these things are pretty dependable.
Still, this overall reliability is little consolation if you happen to be one of the unlucky few who falls victim to a “bad” drive. So most hard drives these days also include a system of sensors that monitors various parameters of the drive’s performance and can provide the results to the host computer. This system, called SMART (for Self-Monitoring Analysis and Reporting Technology ) can’t detect every problem; for example, it’s better suited to identifying gradual performance degradation and increases in the number of read/write errors than it is at predicting instantaneous, catastrophic failure, and it won’t detect software issues such as a corrupt disk directory. But it’s a useful tool that can significantly decrease your chances of falling victim to data loss: If the SMART system indicates problems, you should back up your important data and then consider replacing the drive. (If the drive is still under warranty, many drive/computer manufacturers will replace the drive based solely on a “failed” SMART test.)
There’s just one problem with SMART—it’s useless on its own. It requires software on the host computer that actively communicates with the drive’s SMART system and reports its status to you. So most computers provide some sort of SMART-monitoring feature. Unfortunately, Mac OS X is a bit lacking in this respect. Granted, if you launch Disk Utility (in /Applications/Utilities) and select a drive in the volume list on the left, you’ll see, at the bottom of the window, the drive’s SMART status—"Verified” if everything is OK. But this means that you have to manually check your drives. And who’s really going to do this on a regular basis?
(You could also use Terminal to check, but the same limitation applies—you still have to do it manually or, if you’re skilled at Unix, set up a script that does it periodically... I think you get my point.)
Luckily, there are a few third–party utilities that automate this process for you by periodically checking the SMART status of your drive(s) and alerting you if a problem is detected. Some, such as Alsoft’s DiskWarrior and Micromat’s TechTool Pro, are commercial, multi-function disk utilities that include SMART-monitoring functionality. However, a more economical—but just as effective—option is one that my colleague Rob Griffiths mentioned earlier this year in an article about preventing disasters: Julian Mayer’s free SMARTReporter 2.0.1 ( ; donations accepted).
Operating as either a menu-bar indicator or background-only process, SMARTReporter monitors the status of all supported drives connected to your Mac. In menu-bar mode, a small hard drive icon appears in the menu bar indicating the current SMART status of your drive(s): green or + for “verified,” gray for “unknown,” or red or - for “failing.” (If your menu bar is getting crowded, you can instead choose a small dot as the indicator or choose to deactivate the menu-bar display altogether; in the latter case, SMARTReporter runs in the background until it detects a problem.)
If SMARTReporter observes a failure of a SMART-monitored drive, it can alert you in a number of ways. In addition to the menu-bar icon, you can choose (in SMARTReporter’s preferences dialog) to be notified via a pop-up alert; by an application or script being launched; or by email. The latter option is especially useful for servers and other remote computers.
You can also choose how often SMARTReporter should check each drive’s status—the default is every 60 minutes—or disable monitoring of a particular drive completely.
Because it uses the built-in SMART-reporting functionality of your hard drives, SMARTReporter can’t warn you of every possible disk problem you might have. And there are a few enhancements I’d like to see—the developer himself notes in the ReadMe that he’s hoping to add better RAID support; support for secure email sending; the ability to send warnings to multiple email addresses; more options for when to send warnings (only on the first error, every error, etc.); drive temperature monitoring; and better multi-user support. But considering the price (free), unless you’re already using a disk utility that provides SMART-monitoring functionality, there’s no excuse not to use SMARTReporter.
(As a side note, I mentioned above that there’s “just one” problem with SMART. There are actually a few other limitations, the most significant one being that SMART is currently supported only for IDE/ATA and SATA drives—in other words, internal drives in recent computers. Due to hardware and software limitations, FireWire, USB, and SCSI drives aren’t able to “report” their SMART status. So you can’t use a utility such as SMARTReporter to monitor the status of external hard drives or internal SCSI drives.)
SMARTReporter is compatible with Mac OS X 10.3 (Panther) and 10.4 (Tiger).
12/15/2005: Article edited for clarification on the lack of SMART support for SCSI/USB/FireWire drives.