Kibbles & Bytes Blog

PRAM and SMC Resets: What are they? Both are sets of chips that live on a Mac’s main logic board. They hold information that can become corrupted under certain circumstances which can then cause performance issues. Before resetting the PRAM or SMC for troubleshooting, you should be sure to disconnect any peripherals to ensure that nothing interferes.

But, before explaining how to reset them, I’ll discuss what each does.

PRAM stands for parameter random-access memory. Today, the actual chips used in Intel-based Macs are really NVRAM (non-volatile RAM), a newer technology (think flash drive) that doesn’t require power to maintain information. The old name ‘PRAM’ carried over in general use from the PowerPC days.

PRAM chips hold information between boots on previous computer settings such as speaker volume, screen resolution, some RAM configuration information and current startup disk selection, among a few other odd settings. If your computer won’t boot while connected to a known-good MagSafe adapter and the power light is on on the charger where it connects to the machine, or if you’re experiencing problems that may be related to any of the settings that PRAM controls, then a reset may be needed.

To reset PRAM:

# Shut down your Mac.
# Locate the following keys on the keyboard: *Command (⌘)*, *Option*, *P*, and *R.*
??You will need to hold these keys down simultaneously in step 4.??
# Turn on the computer.
# Press and hold the *Command-Option-P-R* keys before the gray screen appears.
# Hold the keys down until the computer restarts and you hear the startup sound for the second time.
# Release the keys.

More information on PRAM and resets can be found on “*Apple’s support page.*”:http://support.apple.com/kb/HT1379

SMC stands for system management controller and like PRAM is comprised of chips on the Main Logic Board that control several critical systems on a Mac. These include power (including aspects of sleep), fan speed, and communication with peripherals and internal devices such as the AirPort/Bluetooth and I/O cards, the battery and on laptops the topcase (the keyboard, trackpad and power button), among other functions.

If you are having problems with any of these areas of your computer, an SMC reset may be recommended. However, Apple recommends that the SMC be reset only after all other “*troubleshooting steps*”:http://support.apple.com/kb/HT3964. If those steps fail to correct the problem you’re having, or if your computer simply isn’t powering on while connected to a known-good charger (plugged into a known-good outlet) — even after a PRAM reset — then an SMC reset would be next.

On portables there are two possible ways to reset the SMC. If the battery is removable as on some MacBooks and some older MacBook Pros, just disconnect the power supply, remove the battery, turn the machine over, hold down the power button for ten seconds, replace the battery, plug it back in, and try to turn it on. For machines with non-removable batteries try a keyboard reset by powering the machine off (if it’s functioning), leave the MagSafe adapter plugged in, press at the same time the shift-option-control keys on the left side of the keyboard, and the power button, after a second or so let go. Then try to power it back up if it didn’t do so on it’s own.

On iMacs, Mac minis and Mac Pros, reset the SMC as follows:

# Shut down the computer.
# Unplug the computer’s power cord.
# Wait fifteen seconds.
# Attach the computer’s power cord.
# Wait five seconds, then press the power button to turn on the computer.

??More information on SMC resets can be found at the link above, including a list of troubleshooting steps to take beforehand, as long as your machine is functional.??

“*DiskWarrior*”:http://www.alsoft.com/diskwarrior/ is a software tool that focuses entirely on rebuilding corrupted or destroyed directories on solid state hard drives that have experienced failure. This could mean power failure, RAM failure, OS corruption from failed updates, or anything that could harm the directory structure of data.

Recently, DiskWarrior’s ability to temporarily create a virtual directory that identifies data on a corrupted drive has allowed us to access and rescue more data. In combination with the programs Data Rescue and DDRescue, DiskWarrior has recovered a lot of data over the past couple of months — and thus, has improved our success rate (and customer satisfaction!).

We refer to DiskWarrior as ‘Black Magic’ because it’s hard to understand its methods. I have looked for an explanation of exactly what it does, and if I am to understand it correctly, DiskWarrior will access a drive looking for key directories to begin building a temporary listing of all the data on the corrupted disk. When more data is recognized, the directory structure DiskWarrior creates gets more complex to the point of it looking like an actual hard drive created by the apple install image.

When it’s done scanning the drive, it allows you to replace the corrupted or non-existent directory of the drive and also allows you to preview the new directory structure. If you choose Preview, a new icon will show up on your desktop that looks, feels, and acts like an actual hard drive plugged into the machine you are working on. It’s not though; it’s just a directory that points you to the corrupted drive but makes it look as though the drive itself is fine. You don’t even realize that you are inside the corrupted drive at all, but you can copy and or manipulate the information.

Commonly, we will copy the information from the virtual directory to a storage device, then attempt to replace the corrupted directory to try and rescue the disk so it doesn’t have to be reformatted.

When used with another program like DDRescue, DiskWarrior tends to make things easier rather than use Terminal’s commands to try and repair the .dmg file created by DDRescue. DDRescue will essentially copy block-by-block all the information and file structure from a dying hard drive that isn’t able to be read by normal methods and place all the information gathered this way into whatever file type you wish.

When servicing Apple Computers, most commonly it’s a .dmg file. You can attempt to open the .dmg when DDRescue is done, but most of the time, the corrupted file structure will prevent it from opening because the contents aren’t arranged like a normal hard drive. Using DiskWarrior to work its black magic, the .dmg can often have the directory information replaced in the image taken with DDRescue allowing you to mount and later migrate the data back to the machine once the failed hard drive is either reformatted or replaced and the OS reloaded onto it.

If you are one of the unfortunate souls who boots up your Apple computer and produces a blank blue screen or a flashing folder with a question mark staring back at you, DiskWarrior may be the tool that gets you back in touch with your data.

When it comes to Apple Boot disks, DiskWarrior has rescued many worldwide and the reviews online have definitely given the powerful program a good reputation. The only thing that DiskWarrior is unable to repair is a physical failure in a hard drive; that still falls under the expertise and capability of “*DriveSavers,*”:http://www.drivesaversdatarecovery.com the forensics data recovery specialists.

For years, the U.S. Federal Aviation Administration (FAA) has prevented passengers from using electronics on airplanes, largely during the takeoff and landing procedures. Particularly frustrating have been instances such as Kindle use, where the E-Ink device isn’t using any power or doing anything when a page is loaded, and uses technology comparable to a digital watch to turn the page once a minute. Being told to put devices like this away for ten minutes due to what often appears to be overcautious superstition can be demeaning and incites anger toward airlines.

Consider this change in policy, taken from a fact sheet released this past Halloween:

bq. “Last year, Federal Aviation Administrator (FAA) Michael Huerta recognized the increasing consumer interest in the expanded use of personal electronic devices on airplanes and decided to reconsider when passengers can use the latest technologies safely during a flight.” __(FAA.gov)__

Also on Halloween, the FAA wrote a “*press release*”:http://www.faa.gov/news/press_releases/news_story.cfm?newsId=15254 that announced new guidelines for airlines regarding what devices passengers can use use during flight.

bq. “Passengers will eventually be able to read e-books, play games, and watch videos on their devices during all phases of flight, with very limited exceptions. Electronic items, books and magazines, must be held or put in the seat back pocket during the actual takeoff and landing roll. Cell phones should be in airplane mode or with cellular service disabled — i.e., no signal bars displayed — and cannot be used for voice communications based on FCC regulations that prohibit any airborne calls using cell phones. If your air carrier provides Wi-Fi service during flight, you may use those services. You can also continue to use short-range Bluetooth accessories, like wireless keyboards.” (FAA.gov)

Implementation of these policies will be a great boon in coming months to anyone who travels by air. iPhone and iPad users will soon be permitted to continue reading email or watching films during taxiing and after takeoff. The ‘no cellular usage’ is not a big issue, as not many people get signal at 32,000 feet anyway. However, if the airline offers Wi-Fi, some may soon be able to make internet phone calls during takeoff and landing.

__(Editor’s Note: Now that’s a treat…no trickery! -KH)__

There’s something to be said for positivity. It’s oh so easy to grow angry out of frustration with product failure that we forget how far computing has come in the last few years. Yes, the last few years…not the last five or even the last decade.

Most of you have no doubt encountered Moore’s Law, a postulation of exponential computing capability as opposed to linear progress. Often times, I find myself cursing at diagnostic tools in my office taking “so long” to load or data transfers taking “forever,” that I completely disregard the reality that a few years ago, working on these systems would have been an inspiration.

And so, in the weeks since I’ve returned from New York City, I’ve made a concerted effort to change the attitude with which I enter my work. You may find it twisted, but I hope to encounter problems so that I’ll discover new ways of overcoming them. When taking tech support calls, I push myself to be extra positive with my tone of voice and my confidence that a solution can be met. Oddly, my mind seems to process things far quicker this way and I come up with options/ideas that wouldn’t have presented themselves in a negative, frustrated state.

This week, more than ever, I encourage all of us who run into problems with technology to take it as a learning opportunity as opposed to an opportunity to complain about first world problems. Also, as ever, backing up your files will help you keep a smile on your face in the midst of technological adversity. 🙂

Chris
“*christopherb@smalldog.com*”:mailto:christopherb@smalldog.com