# Booting from USB on a Macbook pro, erase partitions



## nbari (Aug 11, 2015)

I downloaded FreeBSD-10.1-RELEASE-amd64-uefi-memstick.img, created a bootable USB stick, and booted (keeping pressed Alt/option) on a Macbook pro.

The system booted from the USB (FreeBSD), asked to press any key or wait 10 seconds, after that became IDLE, I pressed the  power button to restart it, and for an unknown reason the Mac file system was gone.  Initially I thought it was only an issue with the EFI partition, but after booting with an Mac OS USB stick and opening a terminal, I notice that the full disk schema was changed.

Instead of having this schema:

```
/dev/disk0

  #:                       TYPE NAME                    SIZE       IDENTIFIER

  0:      GUID_partition_scheme                        *251.0 GB   disk0

  1:                        EFI EFI                     209.7 MB   disk0s1

  2:          Apple_CoreStorage                         250.1 GB   disk0s2

  3:                 Apple_Boot Recovery HD             650.0 MB   disk0s3
```

I had now something like:


```
/dev/disk0
#:                       TYPE NAME                    SIZE       IDENTIFIER

1: FreeBSD UFS                                       *251.0 GB   disk0s1

2. FreeBSD Swap                                           4 GB  disk0s2
```


Any idea of how could this happen? The problem I see, is that anyone wanted just to give a try (without installing) may be ending erasing their own system.


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