BackupPC-users

Re: [BackupPC-users] extremely long backup time

2013-05-30 06:58:19
Subject: Re: [BackupPC-users] extremely long backup time
From: Adam Goryachev <mailinglists AT websitemanagers.com DOT au>
To: "General list for user discussion, questions and support" <backuppc-users AT lists.sourceforge DOT net>
Date: Thu, 30 May 2013 20:56:21 +1000
On 30/05/13 18:13, Nicola Scattolin wrote:
> Il 30/05/2013 10:04, Adam Goryachev ha scritto:
>> On 30/05/13 16:57, Nicola Scattolin wrote:
>>> hi,
>>> i have a problem in full backups of a 2TB disk.
>>> when backuppc do fullbackup it takes on average 1866.0 minutes while the
>>> incremental backup takes around 20 minutes.
>>> do you think there is something wrong or it's just for the amount of
>>> data to be backupd?
>> Most likely this is a limitation of bandwidth, CPU, or memory on either
>> the backuppc server, or the machine being backed up.
>>
>> Have you enabled checksum-seed in your config?
>> Are you even using rsync?
>>
>> Remember a full backup will read the full content of every file (talking
>> about rsync because I will assume that is what you are using) on both
>> the client and backuppc server. A incremental only looks at file
>> attributes such as size and timestamp.
>>
>> Can you be more detailed about your configuration, and during a full
>> backup look at memory utilisation on both backuppc server and the client.
>>
>> PS, this question is asked regularly, so you should also look at the
>> archives to see the previous discussions (which have been very detailed,
>> and sometimes heated).
>>
>> Regards,
>> Adam
>>
> i use smb to transfer file, and there are not be cpu or bandwidth 
> limitation, it's a local server.
> where is the checksum-seed option? i can't find it

OK, so this is even more obvious.

An incremental will only look at the timestamp, and transfer all files
newer than the timestamp of the previous backup.
A full will transfer ALL files, therefore this is disk I/O + network
bandwidth limited.

2TB of data will take 335 minutes at 1Gbps (assuming you can read from
the source disk at least 1Gbps, and write to the destination disk at
1Gbps, and utilise 100% of source/destination disk bandwidth as well as
100% of network bandwidth, and there was nil overhead for handling each
individual filename/etc...

You are getting just under 20MB/sec, which is probably not unreasonable.

As mentioned, if you want it faster, you will need to determine where
the bottleneck is, which means looking at disk IO (most likely), network
bandwidth, CPU (especially if you use compression on the backuppc
server), etc...

Regards,
Adam


-- 
Adam Goryachev
Website Managers
www.websitemanagers.com.au


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