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Date:      Fri, 15 Nov 2002 18:01:02 +0100
From:      hymette@wanadoo.fr
To:        Jerry McAllister <jerrymc@clunix.cl.msu.edu>
Cc:        freebsd-questions <freebsd-questions@FreeBSD.ORG>
Subject:   Re: How to backup a disk ?
Message-ID:  <3DD5284E.3080708@wanadoo.fr>
References:  <200211151558.gAFFwE325204@clunix.cl.msu.edu>

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Thank you for this note. Actually as I had a previous version of FreeBSD 
on the small disk but not the same partitions I thought that I could use:

# cd big-disk-partition
# pax -rwX . /mnt/small-disk-folder

to copy each of my partitions, and then edit the fstab on the small disk 
properly. This would avoid me the disklabel steps. But would it work ?

My intention is not to backup the whole system on a regular basis, 
instead I 'd like to have the small disk to serve as repair tool in case 
of crash with one partiton dedicated to backup  documents.

What do you think ?

Jerry McAllister wrote:

>First, I am presuming there is nothing you want to save on the small disk
>(or you have already preserved it somewhere).
>
>While booted to FreeBSD
>Used fdisk(8) to create one large FreeBSD slice on the small disk.
>  fdisk -IB da1  (or ad1 or whatever device the disk is)
>will slice the disk and put a standard boot sector on it.
>Then use disklabel(8) to initialize the slice and add boot blocks 
>  disklabel -w -r -B da1s1  (or ad1s1 or whaever)
>Then use disklabel to edit the partition table on the slice
>Look at what you already have to figure out appropriate sizes.
>  disklabel -e -r da1s1   (ad1s1 or watever)
>    add the partitions as needed.   Note the size is in 512 byte blocks
>    Put '*' in for offset for all but partition a: and c: so disklabel
>    will calculate offset for you.  For a: and c: put in '0'.
>    Take the defaults for fsize (1024) bsize (8192) and bps/cg unless you 
>    really want to play with that.  
>    Omit the comments at the end of the line after #.
>    Partition c: is the whole slice and is type 'unused'
>    partition b: will probably be swap and is type 'swap'
>    The remaining partitions will be files systems and type '4.2BSD'
>Finally, run newfs on the newly created partitions, something like:
>  newfs -b 8192 -f 1024 /dev/rda1s1a   (or Rad1s1a or whatever)
>   ""       ""      ""   ""    ""  e
>    etc
>  Don't newfs the swap partition or the c: partition
>
>Make mount points for the new partitions
>  cd /
>  mkdir newpa
>  mkdir newpe
>   etc
>
>Edit fstab to add entries for the new partitions and mount them
>/dev/da1s1a    /newpa    ufs    rw    2     2
>/dev/da1s1e    /newpe    ufs    rw    2     2
>   etc
>
>mount -a
>
>or just manually mount them
>
>mount /dev/da1s1a /newpa
>mount /dev/da1s1e /newpe
>   etc
>
>Now you can dump restore
>  cd /newpa
>  dump 0af - / | restore rf -
>  cd /newpe
>  dump 0af - /prev_e_mount_pt | restore rf -
>   etc
>
>Now, shutdown your system, swap the drives and reboot.
>If you made the partitions identical (in name eg a,b,e,f,etc, not size) 
>and edited /etc/fstab before dumping root then it should all come up
>with running on the new smaller disk and with the old large disk
>mounted on the /newpa, /newpe, etc mount points.  
>
>Note that everything but the dump /restore can be done ahead of time.
>If you are really worried about losing some thing, you will want to
>do the dump/restore part in single user mode.
>So, after getting all the partitions made and editing /etc/fstab.
>Shutdown/reboot, come up in single user mode.
>Then do 
>  fsck -p
>  mount -u /
>  mount -a   or maybe mount -a -t ufs,nonfs if you have nfs mounts in fstab
>  swapon -a
>Then do the dump/restore operations as indicated above.
>Then, shut down, sap drives and reboot.
>
>////jerry
>
>  
>
>>Thank you in advance.
>>
>>    
>>
>
>  
>




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