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List:       amanda-users
Subject:    Re: Monitor and Manage
From:       Chris Miller <cjm () tryx ! org>
Date:       2018-11-15 18:14:25
Message-ID: 239087515.49973.1542305665673.JavaMail.zimbra () tryx ! org
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Hi Gene,

----- Original Message -----
> From: "Gene Heskett" 
> To: "amanda-users" 
> Sent: Wednesday, November 14, 2018 8:40:36 AM
> Subject: Re: Monitor and Manage

> > 
> > So, let's suppose I fire up all three amdumps at once:
> > 
> Don't do that, instead wrap them in a bash script that will run all of
> them sequentially. And run the script with the backuo users crontab if
> you want it automatic, which IMO it should be.

I am backing up three clients to three separate vtape locations, which I think means \
three different vtape pools. Superficially, there is no problem with this, meaning \
the backups run to completion and collect the expected amount of data. Since each \
separate copy of AMANDA is contacting each independent client and storing the backup \
in independent locations, I don't foresee any cross-contamination or confusion, but I \
confess that I have not analyzed the backups to prove this -- yet. The server is the \
only component that is burdened by the multiple copies of AMANDA, but I don't see \
that demand being reduced by serializing the jobs.

It is true that this is fragile, meaning a future change in configuration could \
change this matrix of independence, but the worst case is concurrent non-zero dumps \
have a race condition, so you're never sure which backup has the most recent copy of \
an overlapping file. The Linux clients run xinet.d, so they are thread-safe, and even \
backingup overlapping DLE will work, but you'll never know which backup has the most \
recent version of a file. On Windows clients, I don't know enough about ZWCService to \
know if it can fork child processes or if it is thread-safe, but assuming it has the \
same functionality as Linux, it suffers from the same problems, of not knowing where \
the most recent copy of an overlapping file might be.

Is there another reason that I don't want to run my backups simultaneously?

Thanks for the help, Gene.
-- 
Chris. 

V:916.974.0424 
F:916.974.0428


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