# BSDInstall and "Entire Disk" option



## RichardM (Feb 6, 2013)

Hello,

When installing "Entire Disk" using BSDInstall, will BSDInstall detect and use any existing partition system on the disk? I was thinking I should dd(1) from /dev/zero before installing, to wipe the partition table, but is this necessary when using "Entire Disk"?


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## wblock@ (Feb 6, 2013)

bsdinstall(8) should handle it correctly.  Also, dd(1) won't erase a backup GPT unless you erase both the beginning and end of the disk.


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## Michael-Sanders (Feb 6, 2013)

How many bytes (or kb etc...) must one dd at the end of the disk?


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## wblock@ (Feb 6, 2013)

GPT is not fixed size, but the standard FreeBSD version is 34 512-byte blocks, allowing for 128 partitions.


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## RichardM (Feb 7, 2013)

Thanks, I didn't know about the backup GPT at the end of a disk. I think what may have happened is this: I installed on a machine with 4GB ram, and bsdinstall set up swap of 4GB. I then added another 4GB ram, and reinstalled. Has bsdinstall just read the previous GPT and kept the 4GB swap? I was expecting 8GB swap, ie, same as physical. But maybe bsdinstall has a limit of 4GB swap anyway.


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