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Chrome OS: Powerwash v. System Recovery and When to Use Them

The two most common suggestions on Chrome OS support forums seem to be "run a powerwash" and "perform a system recovery". All in all, both are usually good advice as a last resort. This quick guide will cover what each is and the differences between them.

Some Background

Chrome OS uses an advanced partitioning design which consists of three total partitions: a stateful partition (where your data is stored) and two root filesystem partitions. In English, your physical hard drive is basically divided into three separate pieces. One piece contains your user data (Downloads, Settings) and the others contain the files needed to boot Chrome OS.

The advantage of this design is so that only one of those filesystem partitions is loaded at any given time. That allows a failed update or other corruption issue to occur without stopping your computer from booting. Magic!

Introduction to Powerwash

Powerwash is a relatively new feature. From a technical standpoint, it really just wipes the stateful partition. Back to English, it only wipes user data. The filesystems remain intact, which means if you've upgraded to the beta or dev channel a powerwash will not put you back to stable.

Powerwash is primarily useful for clearing corrupted user data. That doesn't happen often by any means, but it isn't unheard of either. The primary usage for non-savvy folks is to wipe the device before selling it.

Introduction to System Recovery

Chrome OS's system recovery feature dates back years. It's a critical part of the Chrome OS ideology, and at the core it introduces the ability to erase everything your computer knows and reinstall from a flash drive. In English, this will erase everything, even core files, and restore you back to a "known good" copy of Chrome OS.

Unlike a Powerwash which simply resets the stateful partition, a system recovery really does delete everything. This is the only quick way to revert to the stable channel, and at the moment the process requires a 4GB flash drive.

Wrapping Up

If you only want to delete your profile, do a powerwash. If you want to delete everything, a system recovery is required.

A few quick usage examples:
- I need to wipe a device before selling it. Powerwash
- I need to revert to the stable channel. Recovery.
- I'm troubleshooting and willing to try everything. Powerwash, then Recovery if your issue isn't fixed.

Still have Questions?

There are multiple resources available for the times when we want to know more:

- Official Support Forum:
- Unofficial G+ Community:
- Contact a Chrome Ninja:


In an ideal world, you'll never need this post. With that said, it is 2013 and my printer still jams on a fairly regular basis so I think this is worth sharing on the off chance your technology isn't as perfect as you are. Good luck out there.

For those interested in an even more technical overview, I highly recommend checking out the design docs:
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Ken Yeh
So what happens when you do a recovery without the USB flash drive? That is, you use the key combinations to enter developer mode, and the system takes a few minutes to seemingly wipe the file system. I've always thought that this wiped one of the two root file systems and recovered from the second partition, but I've never gotten any confirmation that this was the case.
+Ken Yeh My understanding is that when invoking recovery mode, the wipe is a Powerwash. When disabling developer mode, a recovery device is required, since it wipes everything and re-installs the OS. I haven't been able to get this confirmed either, however, so it's just a guess.
Ken Yeh
+Craig Tumblison It isn't just a powerwash because it reverts the system back to stable channel. Also, I can confirm that it does not need a USB recovery when disabling developer mode.

This was our wipe and recovery procedure for all our school Chromebooks last year, and we never used a USB image.
+Ken Yeh Hmm, that's interesting, thanks for clarifying. I was required to use a USB image when recovering my Samsung Series 550 a week or so ago, so maybe the new behavior is device specific? I haven't recovered any of my newer devices recently, so I'm not able to verify that.

It's also worth noting that a Powerwash is now used to downgrade channels as well. That behavior wasn't allowed back when this post was written (it's more than a year old). I expect there were a lot of under the hood changes that made that functionality possible.

I don't have the time to do much research on this right now, but I would be very interested in knowing what has changed since last year in terms of how everything works.
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