How do I check my MBR is OK?

philip · Guru Joined: 10 Jun 2003 Posts: 535 Location: Sweden

How can I check that my Master Boot Record, MBR exists and is OK?

(The disk is new and I intend to let my system boot from the new disk by changing the BIOS boot disk order)
_________________
/Phil

mikegpitt · Advocate Joined: 22 May 2004 Posts: 3224

Well, the MBR is the first 512 bytes of the disk. I suppose you could make a copy of it with dd and then verify that it contains some data... but really the most useful thing in the MBR is the partition table. I'd say that if you can see a partition table with `fdisk -l` there is a good chance your MBR is sane.

Some info here you might want to peruse:
http://en.wikipedia.org/wiki/Master_boot_record

philip · Guru Joined: 10 Jun 2003 Posts: 535 Location: Sweden

#fdisk -l /dev/sda looks good:

# fdisk -l /dev/sda

Disk /dev/sda: 240.1 GB, 240057409536 bytes
255 heads, 63 sectors/track, 29185 cylinders, total 468862128 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x5aa63057

Device Boot Start End Blocks Id System
/dev/sda1 * 2048 206847 102400 83 Linux
/dev/sda2 206848 73607167 36700160 82 Linux swap / Solaris
/dev/sda3 73607168 468862127 197627480 83 Linux

I have the most strange problem of booting a new SSD that I have prepared from my previous HDD, se separate post:
_________________
/Phil

mikegpitt · Advocate Joined: 22 May 2004 Posts: 3224

Nothing really seems strange about your fdisk results. I just commented on your other thread about the issue you are having with GRUB and your new SSD...

BillWho · Veteran Joined: 03 Mar 2012 Posts: 1600 Location: US