Incremental backups are big

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Incremental backups are big

Veeam Logoby robbys » Fri Dec 12, 2014 8:31 am

Hello,

I have a backup job of about 3.5Tb. I'm seeing a vib file each day of around 300Gb's. Is this normal?
ex. The job of yesterday had 302,7Gb read and 268,9Gb Transferred. Job's are almost not compresses (dedup friendly) and not dedupped by Veeam, so I get that I lose a lot on that side, but I'm actually not worried about the 268,9Gb number, but more of the 302,7Gb. Is it normal that there is 300Gb's of changes in 24 hours??? (the answer is no, because I do not see this behaviour with our other clients). But how can I troubleshoot this? how can I easely see what is changed in a day?

The disk that has the most data changed is the file server. This is a Windows 2012 R2 machine and it has Windows Deduplication enabled on it's 1Tb hard disk. Can deduplication inside a VM be held responsible for these large changes each day, or do I need to look at files/automatic backup processes of software,...
robbys
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Re: Incremental backups are big

Veeam Logoby Shestakov » Fri Dec 12, 2014 9:14 am 1 person likes this post

Hello Robby,

Could you tell more about those VMs in the backup job, are there Exchange, SQL servers?
For instance, Exchange servers create large amount of transaction logs every day, thus creating a lot of changes in the virtual disk that we need to process on the image level, putting all those changed blocks into the incremental backup file.

Antivirus scanning and defragmentation process between backup job`s runs also can cause this behavior. Since Veeam B&R is an image-based backup solution, it works with blocks, so a change of a file`s timestamp causes copying of the whole block.

Thanks.
Shestakov
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Re: Incremental backups are big

Veeam Logoby robbys » Fri Dec 12, 2014 9:43 am

Hello Shestakov,

it are 50 machines, but only our fileserver looks suspicious for me. 110Gb changed, and this day after day.
As I read your reaction right, this can be caused bij Windows 2012 R2 Datadeduplication inside a VM machine?
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Re: Incremental backups are big

Veeam Logoby Shestakov » Fri Dec 12, 2014 10:01 am

Correct, Windows data deduplication is probably the main root of the issue.
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[MERGED] Very big size of Increment files

Veeam Logoby centneroff » Wed Apr 01, 2015 3:06 pm

Hi, All!

We have: Two VMs with guest OS Windows Server 2012 R2. The VMs are on the different ESXi hosts, ESXi version is 5.5 U2. Each VM has 1,5 TB thin provision virtual hard disk. Data Deduplication is enabled on each volume. This servers are in the DFS namespace and are in the DFS replication group. Also we use Shadow Copies on each partition with 100 GB limit. We use VEEAM B&R for each VM. Backup mode for Backup Jobs - Incremental.

Problem: Two weeks ago the size of increment files became very big. On the average the size is about 200 GB. Before it the size was about 50 GB.

Question: What happened :) We have open case about this problem, but we don't have solution. May be here we will find a member with the same problem?
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Re: Incremental backups are big

Veeam Logoby Shestakov » Wed Apr 01, 2015 3:28 pm

Hi Dmitriy,
Data Deduplication is most likely the reason of incremental backups size growth.
Please review the post about best practices of dealing with MS Server 2012 deduplication. Ask additional questions if you have any.
Another possible reasons, as you can see above are: antivirus scanning, defragmentation process, work of Exchange, SQL servers inside the VMs.
Thanks.
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Re: Incremental backups are big

Veeam Logoby centneroff » Thu Apr 02, 2015 10:41 am

After increment files had become very big, we changed deduplication schedule. Now deduplication perform it's operations only on sunday and saturday.
We have no Exchange or SQL servers inside this VMs.
So, only one reason - antivirus. We removed antivirus(ESET Endpoint Antivirus) yesterday evening. Wating for tomorrows results...
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Re: Incremental backups are big

Veeam Logoby Shestakov » Thu Apr 02, 2015 10:45 am

Sounds good! Let`s wait for several days to see how significantly it will help.
Thanks!
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Re: Incremental backups are big

Veeam Logoby centneroff » Fri Apr 03, 2015 6:29 am

The Increment file of the first VM is 72,3 GB today, But the increment file of the second VM is 256 GB.

But We thanged compression to none on the second backup job...

Is it possible that the difference between increment files of the identical servers is so big in our configuration?
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Re: Incremental backups are big

Veeam Logoby Shestakov » Fri Apr 03, 2015 10:09 am

It`s possible to get the provided difference, especially for the first run after the configuration changes are done. Try to wait for 1-2 more runs and see how it works.
In general it`s recommended to set None (zero) compression level only if you use storage devices with hardware compression and deduplication tools for created backups. But since you switch it off, I would recommend to enable compression and deduplication options in the backup job. Thanks.
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Re: Incremental backups are big

Veeam Logoby centneroff » Tue Apr 07, 2015 7:38 am

It is unreal...

The Increment file of the first VM is 92,9 GB today, But the increment file of the second VM is 533 GB!!!

Is it possible? We,ve returned back the compression on the second backup job to hight.

Configurations of the VMs are absolutly Identical.
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Re: Incremental backups are big

Veeam Logoby Shestakov » Tue Apr 07, 2015 10:48 am

Once it happened, it is possible.
Again, to get smaller incremental backup files, I would suggest to turn deduplication on for your backup jobs(if it`s off now).
Then try to make active full and see what results you will have for further incremental jobs.
What is the size of full backups for those vms and what backup method do you use by the way?
Thanks.
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Re: Incremental backups are big

Veeam Logoby centneroff » Tue Apr 07, 2015 11:03 am

Deduplication for our backup jobs is turned on.
The size of full backup is 1,49 TB, backup method is incremental
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Re: Incremental backups are big

Veeam Logoby Shestakov » Tue Apr 07, 2015 12:57 pm

Dmitiy,
Make a Full backup and new increments should be smaller, since after job configuration changes, increments of the same chain can have different sizes.
As to the fact that same VMs have different incremental sizes, it means that one vm`s data blocks change more often. Despite above-mentioned reasons can be just a greater activity.
centneroff wrote:The size of full backup is 1,49 TB, backup method is incremental
Is it the same for both VMs?
Thanks
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Re: Incremental backups are big

Veeam Logoby centneroff » Tue Apr 07, 2015 1:21 pm

Yes, the settings is the same for both VMs.
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