BackupExec (vRay) + Dell vRanger @VMWare consistency backups

Posted on 2016-07-26
Medium Priority
Last Modified: 2016-11-22
We backup a lot of Windows VMWare VMs with BackupExec 15 (vRay). Symantec BackupExec 15 take a VMWare snapshot mount the vmdk and put a full backup on a deduplication storage.

Later Dell vRanger makes a backup of the same VMs. It takes a VMware snapshot, mount the vmdk and make a incremental backup of this vm. Sometimes vRanger uses CBT (VMWare change block tranking).

Now we are concerned about the consistency of the backups.
Is it okay to make incremental backup form the same VMs with these softwares ?

Thank you,
Question by:tutschi69
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LVL 126
ID: 41729497
Yes, BUT you should ALWAYS ALWAYS ALWAYS ALWAYS test test test and test, Recovery by making a test restore, at least once a week!

There is no point backing up your VMs, if you never TEST a RESTORE!

If you have never tested a VM restore, when you need to you may be surprised by the lack of results!

So, TEST! and check if it matches your expectations!
LVL 12

Expert Comment

by:Mr Tortur
ID: 41729553
Is it okay to make incremental backup form the same VMs with these softwares ?
Well, I don't know why you use 2 softwares instead of one.
Each one of them should be enough, unless there is a requirements somewhere that force you to use both but I don't see how.

I am pretty sure that your vRanger is taking a full backup at some point, because it does not have a forever incremental option AFAIK, as Veeam for example.
So you tell vRanger backup job to use incremental policy, ok, and under this option, you have what they call a "treshold count" to tell vRanger how much incremental backup to run on this job before doing a full backup.

Sometimes vRanger uses CBT
Why only sometimes? :-)
It could and should be ALWAYS, IMHO.

Now we are concerned about the consistency of the backups.
As told by Andrew, there is nothing better than test your own backup by doing a restore, and then at least start the restored VM off-LAN if you see what I mean, checking at least that it is booting and every data and software are there.
LVL 12

Expert Comment

by:Mr Tortur
ID: 41729557
I really don't see why you use both softwares, and it could be interesting for you to tell us !
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Author Comment

ID: 41732517
Hello Mrtortur,

that is grown historically. Before virtualization every customer uses backup exec with backup agents on the physical machines.
After virtualization these customers bought vRanger for VMWare “Image” backups and disaster recovery’s.

So BE was used for GRT and file restores and vRanger for a disaster reovery.
A few years ago it was difficult to restore files with vRanger.
Furthermore you sleep better with two backup technologies on different b2d devices.

Now Backup Exec support VMWare: vRay edition. Same backup technologies like vRanger.
And both uses CBT (change block tracking).

So I’m concerned about two products with uses CBT.

Both programs read the …-ctk.vmdk file. Every changed block  will be recorded in this map file.

I think if you make incremental backup vranger request transmission of only the blocks that changed since the last backup.
After that backup exec will do that.

How can both backups be consistent ???

Thank you,
LVL 126

Accepted Solution

Andrew Hancock (VMware vExpert / EE MVE^2) earned 1200 total points
ID: 41732810
Have a read of this...

from Anton Gostev from Veeam on CBT:

In essence, CBT is all about CTK files, these are the files which contain change tracking information of the corresponding VMDK file.

The concept is pretty simple, and if you are familiar with AD DirSync control, or Exchange ICS (public folders change tracking) – it is essentially the same: global USN (Update Sequence Number) for each object. CTK file describes the state of each block for tracking purposes, and contain USN for each block in the corresponding VMDK. After any block is updated, it is assigned the new global USN (which is previous USN value that was used on previously processed block plus 1). This way, any application can ask VMware API “tell me if this block was changed since THIS moment”, and the API will easily tell that by simply comparing the provided sequence number with the actual USN on each block. If provided USN is smaller than actual for particular block, it means that the block was changed (and needs to be backed up, replicated or otherwise processed). So multiple processes cannot conflict with each other anyhow. Each process just memorizes the USN corresponding to the snapshot that the application created during processing, and next time it will use the memorized USN to query for changed blocks.

There should be one CTK file per VMDK file, and CTK file cannot grow out of proportion with number of blocks in VMDK (as it stores only 1 record per VMDK block). CTK file is also thousands time smaller than actual VMDK, because it stores only a few bytes of information (USN) for each corresponding 256KB VMDK block (I am 90% sure it is 256KB, used to calculate it once using CTK debug/stats data, just don’t remember for sure – unimportant info escapes my head automatically to prevent overload with useless facts ;) . For the same reasons, I/O overhead is barely noticeable with CBT: change few extra bytes to write for each 256000 bytes of data.

The CTK files are permanent, and should not be deleted after backup/replication.

Your backups will be consistent....but the incrementals will be different!

Because the CTK files will be different after each backup!

TEST IT and CHECK for yourself!
LVL 12

Assisted Solution

by:Mr Tortur
Mr Tortur earned 800 total points
ID: 41732811
Hi Tom,
Well, I really don't know everything about everything, but here I already know all what you said in your last comment.
But I don't know a customer with 2 backup tools doing exactly the same thing.

And I disagree with this point :
Furthermore you sleep better with two backup technologies on different b2d devices
Not particulary. I sleep better if I have several backups, 2 or 3 including one offsite, depending of possibilities and money.
But with the same backup tool, once it is tested.
Best thing to do IMHO is to do regular testing to check if your restore work, with only one software.

Having 2 softwares brings issues and is time consuming, by the way :
- 2 competencies to maintain in the IT team
- 2 softwares to maintain, too (updates, upgrades)
- licenses to maintain (contract support)
- and most off all, issues with CBT, which is what you have!

I would compare both software and get rid of one of them.

So IMO your issue is an conceptual / architectural one.
Technically, CBT is not made to be used by several backup softwares for same VMs.
Technically again, if you want to resolve this, one of the 2 products should never use CBT.
I think you cannot do that in vRanger (and still don't understand when you say "sometimes vranger uses CBT"). Maybe in BE v-ray.
LVL 12

Expert Comment

by:Mr Tortur
ID: 41732813
Yes, as said by Andrew, this is not about backup consistency, but incremental chain, which will be broken.
LVL 126
ID: 41732818
If you have any issues with your backup product, and cannot sleep at night change it!

I was only having a conversation with UNITRENDS  yesterday stating HOW IMPRESSED with all were, with their latest appliance, we set it up in JANUARY, and for 6 months now, it's run FLAWLESSEY with fail, we now have complete trust, and we don't even have to check every day.

we checked yesterday, when discussing with UNITRENDS, and again 100% PERFECT, and this backup 1TB every evening or Production VMs, SQL, Exchange, vCenter Server, Active Directory!

Far better, than ANY OTHER application, and we also use Appsure, Veeam, Naviko, Commvault, BE, vRanger ....... and many others, and don't get me started on VMware VDR/VDP or EMC Avamar!


Author Comment

ID: 41732863
Thank you Andrew and mrtortur !

The articel form Anton Gostev is great. That is what I searched.

Have nice day !

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