[Discuss] How do you backup "/" with rsync?

[John Blomfield]

Alan W. Irwin wrote:
> On 2007-12-10 19:40-0800 John Blomfield wrote:
>
>> I have just thought of another option, instead of changing the BIOS 
>> to boot the correct HD. Create a Linux boot CD and copy /boot 
>> directory to the CD, with grub configured to show a menu that boots 
>> from the internal or external HD.
>
> This is somewhat similar to using the grub menu on the internal drive to
> select the external drive for booting which is a method I have already 
> shown
> works fine if you add a stanza to the grub menu and swap disk 
> identities in
> /etc/fstab. Both methods will give you an everyday choice of which 
> drive to
> boot from without fiddling with the BIOS.
>
> However, note I actually don't need that everyday choice since except for
> emergencies and tests, I will always be booting from the internal 
> drive. All I really want to do is to make sure the external drive can 
> be booted
> from in an emergency. Once such obvious emergency is if the internal 
> drive
> fails, and I am waiting for a replacement.  In that case, I am going 
> to be
> fiddling with the BIOS in any case, and both the CD grub method will fail
> because the first drive will now be the external drive rather than the
> (presumed defunct) internal one, and the grub menu on the CD will 
> point to
> the wrong drive.
>
Yes, you are quite right, if your internal HD fails your BIOS will 
probably hang and you will need to go into BIOS setup to delete the bad 
drive from the list. You can switch the BIOS boot sequence at that time.

 From an academic point of view I am not sure where Linux gets its sda, 
sdb, etc information from.  I suspect it may be from the BIOS, "Primary 
Master == sda", "Primary Slave == sdb", etc, in which case even if 
"Primary Master" is dead, skipped or entirely absent, it will still 
identify "Primary Slave" as sdb i.e. it will not rename it sda???

John
> I guess I could fiddle with the BIOS to make the external drive the first
> drive, then adjust the CD grub menu accordingly for that change in drive
> identity, but I might as well use the MBR of the external drive and 
> the grub
> menu on that drive (appropriately adjusted for the BIOS change in disk
> identity) to do the same thing without the CD complication.
>
> Alan
> __________________________
> Alan W. Irwin
>
> Astronomical research affiliation with Department of Physics and 
> Astronomy,
> University of Victoria (astrowww.phys.uvic.ca).
>
> Programming affiliations with the FreeEOS equation-of-state 
> implementation
> for stellar interiors (freeeos.sf.net); PLplot scientific plotting 
> software
> package (plplot.org); the libLASi project (unifont.org/lasi); the 
> Loads of
> Linux Links project (loll.sf.net); and the Linux Brochure Project
> (lbproject.sf.net).
> __________________________
>
> Linux-powered Science
> __________________________
>