Large VIB file on a small static server

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Large VIB file on a small static server

Veeam Logoby stevil » Fri Dec 10, 2010 9:14 am

Last night I tested backup across a measly 2Mbps MPLS WAN link. The server I tested wasa a windows print server. I used best compresssion and WAN Target. The initial VBK file size was only 3.3GB. 12 hours later (at 5am) I reran the job, it took 3.5 hrs to backup, the VIB file was 1.5GB in size, nearly half the original server. I don't understand why the VIB file is so enormous when the print server is very static AND the test was done after hours, i.e. 5PM to 8AM.

Any ideas what's going on here?

Cheers
Steve
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Re: Large VIB file on a small static server

Veeam Logoby Alexey D. » Fri Dec 10, 2010 9:42 am

Hello Steve,

Did you perform any activity such as antivirus scan, defragmentation, etc. in between job runs? B&R queries the number of changed blocks from VMware, so it looks like that VM was actively doing something..
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Re: Large VIB file on a small static server

Veeam Logoby stevil » Fri Dec 10, 2010 10:32 am

It would have had another B&R job run on it locally at that time (the normal job, not the test job). I wouldn't have thought that would have changed any blocks though. Antivirus is installed on the server but scans are only done on a Sunday. No defrag jobs are ever run.
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Re: Large VIB file on a small static server

Veeam Logoby Alexey D. » Fri Dec 10, 2010 10:42 am

Do I understand properly - are you having B&R installation inside your 'small static server'? If so, what are you backing up with it?
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Re: Large VIB file on a small static server

Veeam Logoby stevil » Fri Dec 10, 2010 12:47 pm

No, what I mean is that we have another Veeam backup job which back's up this print server on a nightly basis. I setup another test job to do the WAN test using this printserver as a test. So basically it got backed up twice last night.
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Re: Large VIB file on a small static server

Veeam Logoby Gostev » Fri Dec 10, 2010 12:49 pm

stevil wrote:Any ideas what's going on here?

Something changed 1.5GB of blocks on that server... there cannot be any miracles with this - if some block does not change, ESX changed block tracking never picks it up, so the block never gets copied to VIB.
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Re: Large VIB file on a small static server

Veeam Logoby stevil » Fri Dec 10, 2010 2:11 pm

OK, I'll check the VM and see what's going on on it, or chose something else to test :)
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Re: Large VIB file on a small static server

Veeam Logoby tfleener » Thu May 19, 2011 8:10 pm

In this post you asked if an anti-virus scan had been ran recently.

I too have noticed sometimes a VIB file is very large, relative to the amount of actual data changes, but I am wondering why an antivirus scan would cause this behavior.

We use Symantec Endpoint, and perform weekly scans, and I am thinking this could be a possibly cause for the large VIB file creation on some days.

Can you please elaborate on why AntiVirus Scans could possibly cause this, and if you know if the Symantec Endpoint could be the catalyst for this behavior.
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Re: Large VIB file on a small static server

Veeam Logoby Vitaliy S. » Thu May 19, 2011 9:25 pm

Tom,

When you run defragmentation, move/copy/delete files, perform antivirus checks virtual disk blocks are relocated, thus meaning that all these blocks will be treated as changed ones during next incremental job run.

Thanks.
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Re: Large VIB file on a small static server

Veeam Logoby tfleener » Thu May 26, 2011 4:00 pm

I understand the defrag/move/copy... but I do not understand the antivirus checks (did not know it relocated blocks). I was thinking virus scans a basically a read-only option in most cases.

What brings up my question is specifically regarding antivirus checks. I am trying to verify if Symantec Endpoint updates any blocks during its manual scanning process.

What I have seen is very large incremental backups(VIBS) following our weekend virus scan jobs. I have seen references to Symantec updating the USN journal for NTFS, but that is a single file in NTFS, and it seems it should be be unrelated to CBT in Vsphere.

The only other thought I have is the anti-virus software is using a lot of temporary space for the scan process.
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Re: Large VIB file on a small static server

Veeam Logoby tsightler » Thu May 26, 2011 6:07 pm 1 person likes this post

Well, simply scanning through all your files will generate a lot of changes on the filesystem since the "access time" attribute has to be updated for every file entry. That can create a lot of changes. Of course the changes themselves are quite small, only a few bytes, but Veeam uses 1MB blocks, so for 1.5GB of "changes" you only need to have a single byte changed in 1500 blocks spread across the entire disk. Updating the "access time" could easily generate this much changes, and potentially much, much more.
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Re: Large VIB file on a small static server

Veeam Logoby Gostev » Thu May 26, 2011 7:43 pm

Hint, you can disable last access time updates to prevent this from happening.
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Large Incremental size

Veeam Logoby Daveyd » Tue Feb 07, 2012 2:30 pm

[merged]

I just upgraded to v6 but this was going on with v5 as well. I have several jobs that have large vibs with very little change rate occuirring on the VM.

For example:

1 job
1 VM running Windows 2008 x64 and MYSQL DB.
VM has 3 vmdks, 1 for OS (0:0), 1 for Database (0:1) and 1 for MYSQL Database backup dumps (0:2)
Veeam job is using forward incrementals with weekly, CBT, Page File Exclusion, use inline Dedupe, NO compression (backing up to Exagrid), LAN target and is set to only backup 0:1 and 0:2
The job kicks off at 2:15am every day.

On 2/6 at 2:00am adding the Used MB for both my OS and Database drives, it came to 108,357MB (C: 26,962MB/D: 81,395MB). On 2/7 at 2:00am the total Used MB for both drives was 108,577MB (C: 26,966MB/D: 81,611MB). According to my math, in a 24 hour period, the server grew 220MB.

The incremental ran last night on that server. The size of the .vib was 18.2GB!!

Something does not seem right. Am I missing something here??
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Re: Large Incremental size

Veeam Logoby foggy » Tue Feb 07, 2012 3:16 pm

Dave, what about disks fragmentation? I would recommend that you try to defragment your VM disks plus running sdelete on them and see whether this helps.
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Re: Large Incremental size

Veeam Logoby Daveyd » Tue Feb 07, 2012 3:49 pm

I have not defragged or run sdelete on any of the VMs yet and they have been running for quite some time. I assume running defrag/sdelete would be best done right before a full backup? It seems like defragging a vmdk would change an awful lot of blocks if it were heavily fragmented and would result in a pretty big vib.

Also, is there a reason why the v6 Veeam Enterprise Manger, in the Reports section when I go into a job, the "Data Transferred" column does not give the actual amount data transferred like it does in the email report I get in the "Transferred" column for each VM?
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