CentOS - Apr 2015 - how can I tell what's on the MBR of /dev/sda?

Subject says it.

I would like to find out if I have anything written on the MBR of a disk 
in my system /dev/sda, or any other device.
If there is something there, is it readable, or recognizable to humans?

thanks,
-chuck

> I would like to find out if I have anything written on the MBR of a disk 
> in my system /dev/sda, or any other device.
> If there is something there, is it readable, or recognizable to humans?
sudo dd if=/dev/sda bs=512c count=1 | hexdump -C

-- 

rgds
Stephen

On 4/9/2015 5:22 PM, Chuck Campbell wrote:
> Subject says it.
>
> I would like to find out if I have anything written on the MBR of a 
> disk in my system /dev/sda, or any other device.
> If there is something there, is it readable, or recognizable to humans?
the MBR contains both binary boot code, which is not human readable, and 
the master partiion table for the device. you can display the latter like...

$ sudo parted /dev/sda print
Model: ATA Crucial_CT512M55 (scsi)
Disk /dev/sda: 512GB
Sector size (logical/physical): 512B/4096B
Partition Table: msdos

Number  Start   End    Size   Type     File system  Flags
  1      1049kB  525MB  524MB  primary  ext4         boot
  2      525MB   512GB  512GB  primary               lvm


note tho, that if "Partition Table" instead says gpt, then the disk is
formatted GPT and doesn't use the MBR.

$ sudo parted /dev/sdb print
Model: ATA ST32000644NS (scsi)
Disk /dev/sdb: 2000GB
Sector size (logical/physical): 512B/512B
Partition Table: gpt

Number  Start   End     Size    File system  Name  Flags
  1      65.5kB  2000GB  2000GB               pri   raid


-- 
john r pierce, recycling bits in santa cruz

On 04/09/2015 07:22 PM, Chuck Campbell wrote:
> Subject says it.
>
> I would like to find out if I have anything written on the MBR of a disk
> in my system /dev/sda, or any other device.
> If there is something there, is it readable, or recognizable to humans?
Running "file -s /dev/sda" will tell you quite a bit about what's
there.

-- 
Bob Nichols     "NOSPAM" is really part of my email address.
                 Do NOT delete it.

On 4/9/2015 8:34 PM, John R Pierce wrote:
> On 4/9/2015 5:22 PM, Chuck Campbell wrote:
>> Subject says it.
>>
>> I would like to find out if I have anything written on the MBR of a 
>> disk in my system /dev/sda, or any other device.
>> If there is something there, is it readable, or recognizable to humans?
> the MBR contains both binary boot code, which is not human readable, and 
> the master partiion table for the device. you can display the latter
like...
>
> $ sudo parted /dev/sda print
> Model: ATA Crucial_CT512M55 (scsi)
> Disk /dev/sda: 512GB
> Sector size (logical/physical): 512B/4096B
> Partition Table: msdos
>
> Number  Start   End    Size   Type     File system  Flags
>   1      1049kB  525MB  524MB  primary  ext4         boot
>   2      525MB   512GB  512GB  primary               lvm
>
>
>
Mine looks similar to the above. Partition table is msdos, I have different
partitions, but the number 1 is my /boot, where grub is installed, and it shows
as type ext2.

However, when I try to boot it grub says
Filesystem type unknown, partition type 0xee

and won't load /vmlinuz

Googling this says it is a GUID partition table (gpt), in spite of what parted
said???

-chuck


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