10.8 Clean install question.

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10.8 Clean install question.

i have lion installed on my macbook and i am about to install mountain lion. im going to do a clean install, i have made a bootable usb and am ready to go. my question is this. if i use disk utility (ran from the USB drive) erase the HD will it remove all the partitions that lion made (the main system partitions and the recovery partition). i want all the data and partitions gone and for the HD to be a "true" blank slate before i install mountain lion (im ocd that way lol)

any info would help, thanks

Mac OS X (10.7.5)

Posted on Nov 19, 2012 4:33 PM

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Answer 1

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Munas

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Nov 19, 2012 4:49 PM in response to 12oz Mouse

Disk Utility will not display “Recovery HD” on it’s own because it’s a hidden partition, meaning you can’t just go into the app and delete it. What you can do though is format the entire drive though. This is sort of the nuclear approach but it works to delete the recovery partition too.

Boot the Mac from a recovery DVD, USB key, or an attached drive

Launch Disk Utility

Right-click on the Disk (not the partitions) and select “Erase”

Select the default Mac OS Extended (Journaled) as the file system, and give the drive a name

Click on “Erase” to completely format the drive – you will lose all data on the drive and all partitions.This formats the drive giving you a clean slate to start from.

to make sure you may use terminal command before and after format

diskutil list

this will display all the partitions on your disk

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Answer 2

12oz Mouse Author

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Nov 19, 2012 4:51 PM in response to Munas

Thanks for the help Munas, i knew that you could not see the hidden partitions from disk utility, what i wanted to know was what was the best way to wipe all those partitions out (hidden or not) and you helped with that.

Thanks

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Answer 3

12oz Mouse Author

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Nov 19, 2012 5:08 PM in response to Munas

follow up question, after i do an erase per instructions diskutil list is showing i have 10 "identifier" partitions, is that normal.

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Answer 4

Munas

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Nov 19, 2012 5:12 PM in response to 12oz Mouse

10 ??? !!!

just checked my macbook pro runing ML

it has 5 (I have two patitions) if you use single partition your results should contain 4 after the installation

GUID_partition_scheme

EFI

Apple_HFS whatever you call it

Apple_boot Recovery HD

so since you have nothing on that disk I think it should be 1 or two at most...

what are the sizes of these partitions and are you sure you are looking to the computer disk partitions and not USB or what you have booted from...?

How many /dev/diskX you have ?

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Answer 5

12oz Mouse Author

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Nov 19, 2012 5:23 PM in response to Munas

ok so

(Hard drive 250GB)

/dev/disk0

GUID_partition_scheme

EFI

Apple_HFS Mac

(USB Drive 8.1GB)

/dev/disk1

GUID_partition_scheme

EFI

Apple_HFS Mac OS X install ESD

(Dont Know 1.3GB)

/dev/disk2

Apple_partition_scheme

Apple_partition_map

Apple_HFS Mac OS X Base System

now from this point on

/dev/disk3 - /dev/disk13 are all untitled partitons rangeing from 524K to 6.3MB

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Answer 6

Munas

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Nov 19, 2012 5:24 PM in response to 12oz Mouse

I think that /dev/disk0 is the disk on your Mac

all the rest is on your boot device, USB probably...

check the size of GUID_partition_scheme on /dev/disk0 it should be the size of your Mac disk

if yes, than your are fine and it is time to start installation 🙂

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Answer 7

12oz Mouse Author

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Nov 19, 2012 5:24 PM in response to Munas

i editied the info post with the sizes

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Answer 8

12oz Mouse Author

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Nov 19, 2012 5:25 PM in response to Munas

i just dont know if those untitled partitions are on that USB drive or on my HD

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Answer 9

Munas

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Nov 19, 2012 5:25 PM in response to 12oz Mouse

is your hard drive size 250GB ?

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Answer 10

12oz Mouse Author

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Nov 19, 2012 5:27 PM in response to Munas

i have my orginal snow leopard DVD i guess i could boot from it do an erase and then do a diskutl list and see if those partitions are still there

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Answer 11

12oz Mouse Author

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Nov 19, 2012 5:27 PM in response to Munas

yes my HD in my macbook is 250GB

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Answer 12

Munas

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Nov 19, 2012 5:29 PM in response to 12oz Mouse

you may do it as well, however if your mac disk size is 250GB you are good to start installation.

or you may run disk utility once again and check the sizes and partitions

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Answer 13

12oz Mouse Author

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Nov 19, 2012 5:28 PM in response to Munas

ok, thanks for your time Munas i should have it sorted now

have a good one

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Answer 14

Munas

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Nov 19, 2012 5:29 PM in response to 12oz Mouse

good luck 🙂

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Answer 15

12oz Mouse Author

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Nov 19, 2012 6:06 PM in response to Munas

Just a lil update, these 6 partions are still there i have no idea what they are for or if they are supposed to be there. im gonna make a new post with just this info and see if i can get some some info

/dev/disk2

0: untitled *524.3 KB disk2

/dev/disk3

0: untitled *524.3 KB disk3

/dev/disk4

0: untitled *524.3 KB disk4

/dev/disk5

0: untitled *524.3 KB disk5

/dev/disk6

0: untitled *524.3 KB disk6

/dev/disk7

0: untitled *1.0 MB disk7

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