BackupPC

Thomas Temp  writes:

> I've been working on Windows ACL support for BackupPC.
> Here's my approach :

Thanks for looking into this.  One problem is that I have found
rsync/ssh/cygwin to be generally unreliable, so I use only
rsyncd/cygwin.  I wasn't aware of setacl on SF.

My long-term hope would be to modify rsync to fetch the ACLs
and send them.  Some people have posted some patches to rsync
to make this possible.

The idea is that BackupPC would not translate the ACLs - the ACL
data would be kept in opaque form in the attrib file (just like
the other file modes).  On a restore, BackupPC would send the
exact raw data back to the remote rsync.

>  - it is not well integrated in the BackupCP code. I inserted code in
>  BackupPC_dump and BackupPC_restore, but a new module could be more
>  appropriate. I am not satisfied with my choice of config parameters.
>  Variable expansion in config parameters is ad-hoc, and
>  there could be some issues if the values interfere with regexp
>  syntax --I believe there is alread expansion code hidden somewhere in
>  BackupPC. Also, my Perl looks like I was writing Python code;)
> 
>  - its output is not logged. I watch it from the command-line. So, no
>  error reporting from the user's point-of-view.

If you look at the end of BackupPC_dump you will see a function
UserCommandRun().  This shows an example of using $bpc->cmdVarSubstitute
to do variable substitution and shell escaping, and $bpc->cmdSystemOrEval
to actually run the command writing the output to the log file.

> I would also like comments by people who are familiar with Windows ACLs.

Yes, I would too.  I really don't understand Windows ACLs and the
security model very well.

> The Free Software offering for backup is strong and rich, but Windows
> ACL backup is still mostly missing. Not for long, I hope.

I agree.

Craig

"Kenn Humborg" writes:

> This patch adds the 'condrestart' option to the redhat init
> script.

Thanks.
Craig

Hello,

I've been working on Windows ACL support for BackupPC.
Here's my approach :

I first let the normal backup process run, using ssh+rsync. Then I
call setacl.exe (http://setacl.sourceforge.net) through ssh to dump
the ACLs of the saved files. I put it in
$TopDir/pc/$hostName/$shareName/acls.


Upon restore, I modify this list to only contain the selected files,
and to reflect the new location they are being saved to, and then I
call setacl.exe again on the target host to restore the ACLs.

I believe that the approach of using a second channel to save ACLs
separately from the files is good, because regular file transfer tools
that support ACLs tend to also do all kinds of semantic mappings, and
we might as well loose information in the round-trip --especially
regarding the richer w2k/xp semantics. Cross-platform ACL support also
implies that you have included your BackupPC server in your Windows
or ActiveDirectory domain --a pain to set up.

Here are some of the shortcomings of the current implementation:

 - it relies on sshd. We could do something with samba's smbcacls, but
 I feel it is much too primitive for serious ACL backup. Maybe it
 should be patched to support SDDL (MS's textual ACL description
 language) first. Then we could get a 100% Samba solution.

 - it only works if ssh+rsync are used to back up each Windows
 client. Nothing one can't do, but a little bothersome to setup. I
 believe it should be possible to use setacl's network support to use
 a single Windows "pivot" server (with sshd) to manipulate ACLs on all
 the other computers of a domain.

 - it is not well integrated in the BackupCP code. I inserted code in
 BackupPC_dump and BackupPC_restore, but a new module could be more
 appropriate. I am not satisfied with my choice of config parameters.
 Variable expansion in config parameters is ad-hoc, and
 there could be some issues if the values interfere with regexp
 syntax --I believe there is alread expansion code hidden somewhere in
 BackupPC. Also, my Perl looks like I was writing Python code;)

 - its output is not logged. I watch it from the command-line. So, no
 error reporting from the user's point-of-view.

 - it is not well tested. The ssh command's special character
 expansion is still magic to me, so I may have missed some gotchas. I
 got it to work on my Wife's single w2k NTFS disk. I haven't tried
 file or owner names with special or non-ascii characters yet.=20

 - I'm still struggling with Windows permissions (how do I know if I
   have enough of them to backup and restore files and their
   permissions?) and setacl.exe. Right now I'm getting the
   dreaded "The data area passed to a system call is too small" error,
   but I feel it's not my fault so I'm posting this code anyway.

 - I haven't documented it (yet). You need to install SSHD (plus rsync
 and setacl.exe) to get it working. I'll write down my procedure someday.

The two files I've modified, as well as my client config file are
available here :

http://alysse.dyndns.org/tom/misc/bpc_acl/
(search "ACL").

I would greatly appreciate comments on the code by someone familiar
with the BackupPC internals. I will at least try to clean it up and
follow your suggestions before it gets published any further.

I would also like comments by people who are familiar with Windows ACLs.

The Free Software offering for backup is strong and rich, but Windows
ACL backup is still mostly missing. Not for long, I hope.

Have fun,
=2D-=20
Thomas Temp=E9=20
http://alysse.dyndns.org/tom

Big trouble ahead:
http://www.lifeaftertheoilcrash.net/
http://maritimes.buffaloimc.org:8080/news/2004/01/7305.php

Hello,

My backup "suddenly" died a week ago.

Familiar story for developers, and emails starting like that make that
funny chilly feeling of "poor bastard, he didn't realise that
unexplained random errors are close to impossible to fix". Good news,
I got lucky, I believe at least I know the problem, and avoided it. :)

I reconfigured the whole mess and (among other uninteresting
changes) included "--compress" in my rsyncd process' param list.
The results were catastrophic: backups that took 200 minutes usually
died in 200-400 minutes by "received signal=ALRM" or "Child exited  
prematurely"
with no other visible reason (it would be neat to have a bit explanation
about these errors in logfile for the inexperienced or clueless,  
translating
it to "timeout on server/on client/local rsync probably died/remote rsync
probably died/etc"). Zero backups were done on several machines.

I tried various voodoo tricks and finally removed --compress, and
things became shiny happy again.

"Is this the way it has always been?
  Could it ever have been different?"
                              -- Pink Floyd

Thanks,
Peter

This patch adds the 'condrestart' option to the redhat init
script.

Applies to 2.1.0pl1

Later,
Kenn


--- BackupPC-2.1.0/init.d/src/linux-backuppc.condrestart	2004-11-04 =
12:53:41.000000000 +0000
+++ BackupPC-2.1.0/init.d/src/linux-backuppc	2004-11-04 =
12:51:43.000000000 +0000
@@ -77,6 +77,12 @@
   restart)
   	restart
 	;;
+  condrestart)
+        if [ -f /var/lib/BackupPC/log/BackupPC.pid ] ; then
+                stop
+                start
+        fi
+        ;;
   reload)
   	reload
 	;;
@@ -84,7 +90,7 @@
   	rhstatus
 	;;
   *)
-	echo "Usage: $0 {start|stop|restart|reload|status}"
+	echo "Usage: $0 {start|stop|restart|condrestart|reload|status}"
 	exit 1
 esac
=20

"Chad Albert" writes:

> I did not see a startup script for FreeBSD, so I thought I would submit
> mine in case anyone needed it, or wanted to include it in the future
> releases.  This is written for 5.0 and up. 

Just to clarify, what should this file be called?  BackupPC?

Craig

> ------8<---------8<-----
> 
> #!/bin/sh
> #
> #
> # PROVIDE: BackupPC
> # REQUIRE: NETWORKING SERVERS LOGIN
> # BEFORE:
> # KEYWORD: FreeBSD
> #
> # Copy this script to /usr/local/etc/rc.d, then
> # change any paths you have that are different
> # from those below. Finally, add the following
> # to your /etc/rc.conf...
> #
> # BackupPC_enable="YES"
> # BackupPC_flags="-d"
> #
> 
> . /etc/rc.subr
> 
> name="BackupPC"
> BackupPC_user="backuppc"
> command_interpreter="/usr/bin/perl"
> procname="/usr/local/backuppc/bin/BackupPC"
> rcvar=`set_rcvar`
> command="/usr/local/backuppc/bin/BackupPC"
> load_rc_config $name
> run_rc_command "$1"