[Rear-users] Questions on handling

Schlomo Schapiro schlomo at schapiro.org
Fri Apr 25 17:27:21 CEST 2008

Hi Werner,

I will try to sort your questions:

1. Difference between EXTERNAL & REQUESTRESTORE

EXTERNAL requires you to supply scripts for *backup* and *restore* to 
ReaR and ReaR will call them for you

REQUESTRESTORE will not do anything for backup but halt the disaster 
recovery process after formatting and mounting the filesystems and give 
you a chance to restore the data yourself - that is the magic. After you 
restore the data ReaR will then continue to deal with boot loaders etc.

2. Manual restore not significantly slower than automated

The purpose of ReaR is to
1) assist Linux-unskilled admins to recover Linux systems (your vacation 
replacement, for example)
2) to assist in restoring *lots* of systems, e.g. if your data center is 
gone and you need to restore all systems into a new data center.

For all other purposes a skilled Linux admin does not really need ReaR 
to restore a system from backup.

3. RSYNC_SSH outside script

This is a question about bash and variable scope. Bottom line is that 
something you set in a bash script stays local to that script as a local 
variable. If you want to set this globally, use /root/.bashrc (for root 
only) or /etc/profile (or /etc/profile.d/rsync.sh or something like 
that). BTW, this is not a ReaR related question ...

4. I am looking for customers to sponsor more backup software 
integration, so maybe your place might be interested in having NetBackup 
implemented ?


PS: I do not follow you about a VM not beeing accessible ... ?

PPS: I have a feeling that you are trying to do something very complex 
for a very simple problem.

Werner Flamme wrote:
> Schlomo Schapiro   [23.04.2008 20:55]:
>> Hi Werner,
>> well, the documentation is somewhat lacking still, though I hoped that the 
>> general part would be sufficient to cover your question (feel free to submit 
>> better documentation :-))
> Hi Schlomo,
> I'd like to, given the case that I understand what I do :-)
>> Implementing support for another backup solution is fairly simple, took me 2-3 
>> days each time.
> The only client installed on the hosts is a Java client, and I do not
> want to automate the restore here ;-) The time I need for restoring
> manually compared to automated restore is - nearly the same...
>> The backup methods REQUESTRESTORE and EXTERNAL are special because they don't 
>> take anything into the rescue system but expect some "magic" to restore the data 
>> when requested or allow specifying your own custom scripts. But it is always 
>> better to write a support module for your backup software because that would 
>> allow you to fully utilize the power of rear and also contribute your effort 
>> back to the project.
> For EXTERNAL, I saw this from /etc/rbme.conf, but what kind of magic
> does REQUESTRESTORE expect? EXTERNAL allows to include user-written
> scripts doing the work, initiated by rear (that is really great!), and
> REQUESTRESTORE just says "Restore now!" and it's work is done, right? ;-)
>> One popular example for REQUESTRESTORE is having the backup done with rsync 
>> (e.g. RBME) and then obviously the backup server has to push the data back to 
>> the system (using rsync over ssh). If you are looking for a simple backup 
>> solution besides NetBackup, do take a look at RBME as it simplifies the rsync 
>> backup.
> At the moment, I do not know why my parameters vanish...
> In /etc/rbme.conf I have (amongst others)
> RSYNC_SSH="ssh -i /root/.ssh/rbme-rz36-key"
> In /usr/bin/rbme, I changed (~ line 110):
> test -s "/etc/$ME.conf" && . "/etc/$ME.conf" && echo "/etc/$ME.conf
> gelesen" > /root/rbme.log
> env | grep -i rsync >> /root/rbme.log
> In /root/rbme.log I see:
> /etc/rbme.conf gelesen
> Outside the script, RSYNC_RSH is unset.
>> Regards,
>> Schlomo
>> PS: If you want to quickly test the workings of rear, simply use
>> NETFS_URL=nfs://host/share/path
>> and make sure your system can NFS mount that url. The SLAC demo was just the 
>> same, the demo film on the website also shows this in detail.
> Hm... At present, I do not have a system that is small enough to fit
> into any of the NFS shares avalable to me :-( And virtual machines are
> hardly accessible either, but with the EXTERNAL option I may gain a lot
> - just a script that creates tarballs for the relevant directory trees,
> puts them to a certain place and copies them away via rsync. To get them
> back, same thing, other direction ;-)
> I'm just feeling depressed because the SLAC demo was so nice, and my
> tries aren't... ReaR can do it, but I can't :-(
> Regards,
> Werner

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