BackupPC-users

Re: [BackupPC-users] Unnecessary reads with rsync?

2016-08-05 03:41:53
Subject: Re: [BackupPC-users] Unnecessary reads with rsync?
From: martin f krafft <madduck AT madduck DOT net>
To: backuppc-users AT lists.sourceforge DOT net
Date: Fri, 5 Aug 2016 09:41:22 +0200
Thanks Adam for your patience and insights! And everyone else for
putting up with me! ;)

also sprach Adam Goryachev <mailinglists AT websitemanagers.com DOT au> 
[2016-08-05 01:12 +0200]:
> > But instead of (what seems to be) chunk-wise checksum transmission,
> > why don't we (also) store the whole-file checksum on the server (can
> > be computed in the same pass) and at least give people the option to
> > risk reading every file once to compute this checksum, if it means
> > being able to skip files without further ado or large data
> > transfers?
> A couple of possibilities:
> a) you haven't enabled checksum caching (--checksum-seed=32761)

I have…

> b) you haven't completed at least 2 full backups including this file

I have…

> c) you haven't configured backuppc the way you want it
>    (RsyncCsumCacheVerifyProb)

$Conf{RsyncCsumCacheVerifyProb} = '0.01';

So yeah, there is the (1%?) chance that BackupPC chose to revalidate
the file in question, but I kinda consider that unlikely.

Is this recorded somewhere? I can't find anything in the logs. What
LogLevel would be required for this to show up?

> PS, backuppc v4 does store full file checksums, but you probably
> still want to verify the block checksums of the file from time to
> time on the slim chance that the full file checksum matches but
> the content is different.

I might have to look into that ;)

Has anyone managed to make BackupPC run from source?

-- 
@martinkrafft | http://madduck.net/ | http://two.sentenc.es/
 
"die ideen, für die wir bereit wären, durchs feuer zu gehen,
 sind oft nur der grund, das feuer zu legen."
                                                  -- jeannine luczak
 
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