Exchange - CBT question

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Exchange - CBT question

Veeam Logoby b.lagace » Thu Aug 27, 2015 12:29 pm

Hi all,

Probably a silly question, but just to be sure.

Say I have a VM running on Hyper-V which hosts an Exchange database.
Change block tracking on the VM is not supported (due to specific hardware).
Doing an application aware backup of that VM will still trigger the VSS inside the vm and be capable of doing an incremental backup of the database, right?
It will use the exchange logs to determine what to backup and not read the full DB to find the changes?

So in my specific case the VM will be fully scanned for it's C-drive(100GB) and changes will be send over to the repository
Exchange logs will be consulted to send over the changes of the database(1TB) without fully scanning it.
So I'll have read 100GB+the changes and not 1,1TB.

Don't ask, just accept CBT is not possible on that system :-).

I can't test it, as I need the answer first before migrating the data.

Thx in advance
Bjorn
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Re: Exchange - CBT question

Veeam Logoby v.Eremin » Thu Aug 27, 2015 1:01 pm

Yep, if VB&R fails to use its proprietary CBT mechanism, then, it will scan full VM image to understand what has been changed since the last run. Thanks.
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Re: Exchange - CBT question

Veeam Logoby b.lagace » Mon Aug 31, 2015 7:36 am

Sorry, but I don't fully understand.
Agree that if the proprietary CBT mechanism fails, it will scan the VM to find the changes.
But will it also scan the EDB files fully from Exchange or will it make use of the LOGS to know the changes there ?
Never done application aware backups before...
thx
Bjorn
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Re: Exchange - CBT question

Veeam Logoby foggy » Mon Aug 31, 2015 11:22 am

Bjorn, Veeam B&R is an image-level backup solution, it does not look into files but rather at virtual disk blocks. The fact the backup is application-aware means that the data that is being copied is transactionally consistent.
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Re: Exchange - CBT question

Veeam Logoby b.lagace » Mon Aug 31, 2015 1:29 pm

Hi Foggy,

Thx, I fully get it (again) :-)

In short terms : no cbt = screwed

Regards,
Bjorn
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Re: Exchange - CBT question

Veeam Logoby foggy » Mon Aug 31, 2015 1:44 pm

No CBT means longer backup due to the need to scan the entire VM for changes, however only changed blocks are transferred.
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Re: Exchange - CBT question

Veeam Logoby b.lagace » Mon Aug 31, 2015 1:55 pm

Agree, but most also forget the impact on your storage system.
Say you have 8TB of vm's....and you need to read everything first before you know what to backup...
I currently tuned my setup and I reach 1GB/s in reading terms :-) (that BYTE and not BIT).
But I can only advice customer that are shopping for new SAN/NAS ...make sure it's capable of handling CBT. (so forget about linux SMB 3.0 share stuff)
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Re: Exchange - CBT question

Veeam Logoby foggy » Mon Aug 31, 2015 3:07 pm

Yep, that's a definitely valuable recommendation.
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