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Joined: Oct 06, 2011 4:09 am
Full Name: Rowan Page

Replica Differential Size

Post by Pagey »

Hi Guys,

Just a general question, I took a copy of our backups to our DR site yesterday for seeding replicas.

All going pretty well so far have created 2 VM replicas of about 20 so far =)

Just a little concerned about the amount of data being moved, I am in no way blaming the Veeam software, I am assuming this data is being marked by CBT and therefore Veeam is transferring it to the replica.

But as an example, I started a replica job of an idle windows 2003 server 5 minutes after it last ran and it transferred 240Mb. I am trying to determine if I have something going on in my environment that is unusual, or if this is consistent with other peoples experience. I wouldn't have though 240Mb of "real" data changes would have occurred on this VM in 5 mins.

I am hoping to replicate at least 4 or 5 of these VM's overnight, we are looking at a Midband Ethernet Connection, but at this stage it is over an ADSL2+ AnnexM connection (I throttle the VPN Link the backups go over to 1600kbps, leaving around 150kbps of room during backups), obviously you would need alot more information regarding my site before you could tell me if this is viable (what the VM's do etc), but that isn't really my question, I am just seeking information on others experience with the Replicas, and amount of data "transferred" over WAN's per VM's

30 Staff Site
2 x Active Dir VM's = 2Gb
1 x Exchange 2007 VM = 3Gb
1 x SQL Server VM = 5Gb

I will report back when I have more data, I obviously need to finish creating my jobs first, I am just trying so get a feel for if my implementation is "normal", what I could expect in other sites, both bigger and smaller for other clients etc.

Cheers - Pagey
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Full Name: Luca Dell'Oca
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Re: Replica Differential Size

Post by dellock6 »

Only a powered-off server does not change anything. Even an "idle" server has paging activities, log writings... 240 Mb is a really low value, and is a good value for an idle server anyway.
Luca Dell'Oca
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Re: Replica Differential Size

Post by Gostev »

Keep in mind that application-level quiescence adds some changed blocks. No matter how ofter you run the job, each freeze is a lot of writes because of apps dumping their data to disk. Besides, launch Microsoft Process Monitor and see how many writes totally idle Windows system produces. Hundreds of those every second (not just file system, but also registry). And it all goes to disk.
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