Thanks for the detailed reply. I will follow these steps this weekend and see how far I get.
On Tue, May 5, 2026, at 12:09 PM, G.W. Haywood wrote: > Hi there, > > On Mon, 4 May 2026, [email protected] wrote: > > > The host running backuppc on my network had its root drive fail. > > :( > > > The actual backup storage was on an external drive which I had > > mounted on /var/lib/backuppc. That external drive is still healthy. > > :) > > > I remember spending a lot of time getting backuppc to work just > > right and dread starting over. > > My early recollections are similar but I wrote it all in my notebook. > It's a habit I developed in my first job - at an explosives research > laboratory in 1971. It's a habit I've kept up ever since, and over > the years it's sometimes been incredibly useful. > > > Since the external drive includes the backup for localhost (the > > former box running backuppc), it should include a backup for > > /etc/backuppc and the config.pl file (I forget which directories I > > set for backup for localhost; hopefully I included /etc). > > Hopefully. Hmmm. > > > It seems there should be a way I can extract my now-lost > > /etc/backuppc/config.pl and other files in that directory. I am > > hoping I can install backuppc fresh, then grab the /etc/backuppc > > files from the external drive, and swap them in. Is this possible? > > Hopefully. If you didn't back up the files, they're probably gone. > > You didn't say what version of BackupPC you're using, so I assume V4. > > First I suggest that you make a copy of your backup drive on another > medium of some sort. Put that copy somewhere safe. Next install a > new version of BackupPC the same way that you installed it originally, > for example if you used a distro package use the same distro package. > At this stage don't try to connect the old backup drive (nor the copy) > but simply get the BackupPC system working. You can use any old host > on the network as a dummy to start making backups. To get you started > set up the configuration to back up one file on it, say every hour or > something like that. > > Once you have the new BackupPC working, shut it down - so that now the > BackupPC script isn't running. Now edit the BackupPC 'hosts' file so > that it contains the hosts that you had on the original system (if you > can't remember them, the hostnames are the names of directories in the > directory .../pc/ of the BackupPC backup data store). > > At this point, if you started BackupPC, it could try to start backing > up your hosts. Presumably you won't want it to do that because you'll > have individual configurations (for example in /etc/backuppc/pc/ [*]) > for each of your hosts, and before starting the backups you'll want to > get those configuratons from a backup. You can do that as follows: > > Replace the 'new' backup store with your 'old' backup store. I'll let > you work out how to do that, from what you've written you're obviously > capable of doing it. When you've done it, you *could* start BackupPC, > but you still don't want to start backups - you still don't have your > old configurations. However, you *can* now use the tools provided by > BackupPC to get files and directories from the backup data store... > > 'BackupPC_ls' lets you list the files in any directory from any backup > of any share of any host. It gives you an md5sum for each file listed. > Here's an example, where I'm logged in as root on the backup server: > > 8<---------------------------------------------------------------------- > > # su -c "/usr/local/BackupPC/bin/BackupPC_ls -h alpha -n 2235 -s Config /" > backuppc > /: > -rw-r--r-- 0/0 290 2019-09-26 01:24:33 /.fstab > (0416cfcbe01474d6f0526ffa5d890813) > drwxr-xr-x 0/0 0 2020-05-07 15:45:30 /.java/ > -rw------- 0/0 0 2019-09-26 01:05:24 /.pwd.lock > (d41d8cd98f00b204e9800998ecf8427e) > drwxr-x--- 0/1002 0 2026-03-26 13:55:12 /BackupPC/ > drwxr-xr-x 0/0 0 2025-02-01 16:36:24 /ImageMagick-6/ > ... > ... > > 8<---------------------------------------------------------------------- > > As you can see, BackupPC_ls (normally) has to be run under the ID of > the backup user, usually 'backuppc' but of course that's configurable. > You give it the host name, in this case 'alpha', the backup number, in > this case 2235, the share name, in this case 'Config', and the name of > the directory that you want to list, in this case '/'. The output is > a bit like that from 'ls -l' but you get md5sums for the files (not > for directories). In my example above I've given the full path to the > BackupPC_ls utility, it will likely be different in your installation. > If you can't remember the share names, they're in the numbered backup > directories under the host name directory with 'f' prefixed to them. > The file 'backups' in the top level of the host's directory shows you > which backup numbers are full and which are incremental. > > 'BackupPC_zcat' then lets you write the content of any file to stdout. > You just give it the md5sum which BackupPC_ls provided for your file. > Below I've recovered the file '.fstab' which has the md5sum '0416cf...': > > 8<---------------------------------------------------------------------- > > # su -c '/usr/local/BackupPC/bin/BackupPC_zcat > 0416cfcbe01474d6f0526ffa5d890813' backuppc > proc /proc proc defaults 0 0 > PARTUUID=6c586e13-01 /boot vfat defaults 0 2 > PARTUUID=6c586e13-02 / ext4 defaults,noatime 0 1 > PARTUUID=6c586e13-03 /var ext4 defaults,noatime 0 1 > # > > 8<---------------------------------------------------------------------- > > You can redirect stdout to a file of course. That's all there is to it. > > > The names on the files on the external drive are all user-unfriendly. > > A consequence of BackupPC's way of de-duplicating things is that the > files in the backup data store don't have the names that they have on > the backed-up storage devices. The name of a file is the md5sum of > the files's content, with the added wrinkle that the file in the data > store will probably be compressed. The pseudo-filesystems under the > BackupPC host name directories index into the data store using md5sums > as pointers. The pool files are split into 128 subdirectories, each > of which is further split into 128 subdirectories, so that for example > my file '.fstab' 0416cfcbe01474d6f0526ffa5d890813 is stored in > > .../cpool/04/16/0416cfcbe01474d6f0526ffa5d890813 as you can see: > > 8<---------------------------------------------------------------------- > > # ls -l /var/lib/BackupPC/cpool/04/16/0416cfcbe01474d6f0526ffa5d890813 > -r--r--r--. 1 backuppc backuppc 117 Apr 21 14:09 > /var/lib/BackupPC/cpool/04/16/0416cfcbe01474d6f0526ffa5d890813 > # > > 8<---------------------------------------------------------------------- > > The file size in the store is only 117 bytes because it's compressed, > if I extract it using BackupPC_zcat I can see the actual file size on > the real storage medium (it was given by the BackupPC_ls output above): > > 8<---------------------------------------------------------------------- > > # su -c '/usr/local/BackupPC/bin/BackupPC_zcat > 0416cfcbe01474d6f0526ffa5d890813' backuppc | wc -c > 290 > > 8<---------------------------------------------------------------------- > > HTH - and I hope the longer lines didn't wrap on your mail client. > > [*] This would be /etc/BackupPC/pc if you installed from source, so > I'm guessing that you used a distro package e.g. Debian to install. > In my view, their almost universal insistence on e.g. changing the > names and locations of files and directories tends to make things a > lot more difficult for everybody. > > -- > > 73, > Ged. > > > _______________________________________________ > BackupPC-users mailing list > [email protected] > List: https://lists.sourceforge.net/lists/listinfo/backuppc-users > Wiki: https://github.com/backuppc/backuppc/wiki > Project: https://backuppc.github.io/backuppc/ >
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