Hi,

I think it would be great to add this in the beginning of the USB Howto



this explain how to start from scratch with an usb stick ...

I will be glad to improve the documentation. But these commands are a bit strange:

You format /dev/sdb1 first, and then you overwrite the partition table...

Since sdb1 depends on the partition table, maybe we should use dd first ?

Doyou know if the kernel is refreshing its partitions after you run dd ?

I can assure you this works great,

It's the only way i could get sysrec usb working

You need to put the mbr in /dev/sdb and the partition table stay


Well try it and then tell me

Maybe yoiu should use this before the other command

dd if=/dev/zero of=/dev/sdb

Yes, it may work for you, but I just want to be sure that the instructions will be okay for all the users.

Ok so give it a try with your usb key and told me your results, those commands won't hurt your system or your stick.

In fact :

As root

This will erase all in the stick, and bring us a brand new clear stick

As root

This will create *ONLY* the partition table with one LBA FAT32 bootable primary partition

As root

This will create the FileSystem FAT32 in the first partirtion

As root

This will add the mbr to the top of your stick

As root

Synchronize the drive

Please explain me where you find I'm wrong ...

Regards,

It just looks strange to format the partition first and then to replace the MBR (which contains the partition table). In case your MBR has a different partition table, then the /dev/sda1 you have formatted may be at another location on the disk, so it will be invalid. Of course it may work when the partition table does not change. But I have not investigated further, that's just my opinion.

I'm not sure the partition table is in the mbr...

Ok i got it

if you go to this page
http://en.wikipedia.org/wiki/Master_boot_record

You will see that Code area take the 440 first bit, and the table partition begin at the 446th or 447th bytes,

So if i do


I didn't touch the partition table ( I tried )

If you make :

You will see that mbr.bin is just 404 bytes long so it won't touch the partition table...


I agree you to put this explication in the Howto :)

Ok, It's better now. I will put that on the handbook immediately. Thanks a lot for that contrib.

You're welcome!

I thank you so much for your questions and your doubt, i learn a lot with that!!!

If you'd like an addition to the "known to work" USB drive list:

I have a 2GB ( 4013710 512-byte hardware sectors) Cruzer Titanium (SanDisk U3 Titanium 3.27 PQ: 0 ANSI: 2) that works great following the manual's guide here:

http://www.sysresccd.org/Sysresccd-manu ... _USB-stick

(on Dec 1st, 08)

Page updated thx

First of all, thanks for your guide, it helped me making my USB-stick boot. Secondly, I could'nt find /usr/lib/syslinux/mbr.bin. when I booted Sysrscd but I found it in /usr/share/syslinux/mbr.bin. Maybe it's because I am using a newer version of Sysrscd.

Dolmio

So the new file must be the right one, I will update the manual. Thanks

Yes you are right we also do it manual.