Support Blog

Mac Troubleshooting with a T2 chip

If disaster ever strikes, and you find you cannot start up your T2 equipped Mac, it helps if you have made a few preparations. The T2 chip that is built into modern Macs provides a number of important features, including security features. By default, this security is very tight, similar to using iOS on an iPhone. This prevents starting up from any external drive or anything other than the current signed OS available from Apple.

cancel mac

Techtool Pro users need more freedom than this security provides, and fortunately, a quick trip to macOS Recovery provides this freedom. After starting up in macOS Recovery, launch the Startup Security Utility, and use it to reduce your Mac's security. More details are available here.

Read more: Mac Troubleshooting with a T2 chip

What to do when Surface Scan finds bad blocks


Whether you have a Solid State or Rotational Drive, Techtool Pro's Surface Scan test may discover bad blocks at some point. A bad block, or bad sector, is a portion of the disk that can no longer be written to. Both types of devices utilize a cache of spare blocks that are used when bad blocks are found in order to ensure that your data does not get corrupted by storing it on a bad block. When the Surface Scan test finds bad blocks, this means that this cache is no longer able to use spare blocks, and your data will be at risk of corruption.

Surface Scan Catalina

In almost all cases, discovering bad blocks means that the drive will need to be replaced. Bad blocks represent physical problems with a disk, and cannot be repaired in software. In rare cases, a rotational drive can get a small lease on life by performing a secure erase on the disk. For rotational drives, this can cause the cache to reset, and may provide a few additional spare blocks. This generally does not work on solid state drives, however.

Read more: What to do when Surface Scan finds bad blocks

Testing Other Components

Recently, we've discussed testing disks and RAM with Techtool Pro. In addition to testing these important areas, Techtool Pro also tests some of the lesser-known components that keep your Mac running smoothly. Your Mac has a number of sensors that monitor the voltages and temperatures going to your Mac's various components. If things get too hot, most Macs utilize fans to keep things cool. And, if your Mac is a laptop, it has an internal battery used to power the device if the power cord is disconnected.

Fan Sensor Batt

Keeping an eye on some of these systems outside of RAM and disks can assist in identifying other areas that may be keeping your Mac from running its best.

Read more: Testing Other Components

Using Techtool Pro with SSDs

Sometimes we're asked if Techtool Pro works with SSDs. Short answer? Yes!

For a longer answer, some of Techtool Pro's features don't really apply to Solid State media. Some of the confusion probably comes from whether it is a good idea to optimize (or defragment) a Solid State Drive (SSD). Techtool Pro does display a warning when attempting to optimize an SSD, because doing so is not recommended.


Defragmentation routines organize the data on rotational hard drive platters so that the data can be read consecutively, without the drive having to move the drive mechanism any more than necessary, which improves read times on rotational disks. SSDs have no mechanical moving parts, and fragmented data can be read just as fast, regardless of the physical location of the data on disk. Furthermore, moving massive amounts of data on an SSD (which occurs during any defragmentation operation) works against SSD-specific features used to keep them running their fastest.

Read more: Using Techtool Pro with SSDs

What about my RAM?

We spend a lot of time talking about drives. And indeed, Techtool Pro includes a number of tests and tools for them. However, perhaps the next most important component when it comes to your data is your Mac's memory (RAM).


Your RAM is temporary storage used to store whatever your Mac is currently working on. Since the operating system can hold on to memory used by other processes that have recently been closed, the Memory Test in Techtool Pro reclaims as much memory as possible before testing. Any memory currently in use by the operating system or reserved by a running application is unavailable for testing. To test the most RAM possible, it is best to quit any running applications. Even better, start up from an eDrive or Protogo device, which have slightly smaller operating system footprints.

Read more: What About RAM?

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