Clarifications on BMR and System State in DPM 2010 RRS feed

  • Question

  • Hello,

    I was wondering if someone could answer a couple of questions that I have about Bare Metal Recovery in Data Protection Manager 2010:

    1) How many data sources does a BMR count as? For example, if I perform a BMR backup on a 2008 R2 box with two "critical volumes", am I using two data sources? Or does BMR consolidate both critical volumes into a single "data source"?

    2) In comparing the DPM 2007 storage calculations (http://technet.microsoft.com/en-us/library/bb795684.aspx) to the DPM 2010 storage calculations (http://technet.microsoft.com/en-us/library/ff399599.aspx), I see a discrepancy in the amount of space required for a recovery volume of Server 2008 System State backup in going from DPM 2007 -> DPM 2010. So, I wanted to confirm that the information in the DPM 2010 calculations is correct. And if so, why the drastic reduction? What changed technically in DPM 2010 with respect to system state backups for Server 2008?

    3) I saw that BMR and System State must be protected within the same Protection Group (i.e. one cannot protect System State and Bare Metal Recovery for the same server in different Protection Groups). But my question is -- can I protect Bare Metal Recovery, which includes "critical system volumes" in Protection Group A, and data on one of those critical system volumes in another protection group (Protection Group B)? For example, let's say I want to perform a BMR and System State backup once per week. BMR includes C: and D:. But D: contains some critical application data that I need to backup once per hour. Can I create a separate protection group for D:\Critcal_App? Or does DPM see this scenario as me trying to protect the same data source in different Protection Groups, and therefore block me?

    4) Am I correct in thinking that BMR isn't really useful for a Hyper-V VM? Wouldn't it be better to just backup the VM via the Hyper-V host? Or am I missing something?

    5) Are Bare Metal Recovery backups always a "full" backup, similar to the way that DPM treats System State? Or does DPM take incremental BMR backups?

    Thanks in advance!

    Tuesday, December 14, 2010 9:02 AM


All replies

  • Hi Frank!

    Here's some answers for your questions.

    1. BMR protection gives you the ability to restore your server operatingsystem to another hardware if your hardware fails. BMR will include your system drive and System state, if you choose the BMR from an avalible member when you create a protection group the System state will be choosen also. You can't make a protection group that just holds the BMR for the servers in your domain, the system state and BMR files must be included in the same protection group (answers question 3)
    2. Regarding the disk allocation made by DPM in 2007 versus DPM2010 Microsoft made some good new features like shrink and co-location of the DPM diskpool. Microsoft probably also mabe optimizations for the disk management of different workloads, including system states. The information in the storage calucator is correct.
    3. Answerd in question 1
    4. BMR isn't useful in a Hyper-V guest since your backing up the VHD file and can use that to restore a system in a disaster recovery situation.
    5. All backups made in DPM uses just block level changes. DPM just triggering the backup of a system state, the technology used if the WSB feature that make the backup locally on the server.

    hopefully I managed to answer your questions.



    Robert Hedblom

    Check out my DPM blog @ http://robertanddpm.blogspot.com

    Tuesday, December 14, 2010 12:56 PM
  • Robert,

    I appreciate your response, but I don't think that you answered question #1 or #3.

    To clarify, in question number 1, I am wondering how many data sources a BMR backup will "consume". I am planning a very large DPM deployment, and will most certainly run into the 300 data source limit per DPM server server, so I need to understand the impact of running many BMR backups. I am wondering how DPM will store the backup -- whether its stored as a single data source, or as multiple data sources (one per "critical volume").

    To clarify question #3, I'm really looking to understand how protection groups can be managed in a very specific scenario. For example, consider a domain controller with its boot/system volume on C: and its Active Directory database/logs/SYSVOL on D:. In this scenario, both C: and D: would be included in the BMR. Let's also say that a critical application is installed on the domain controller, with its data in D:\Application_Data. In this scenario, I might want to do a BMR once per week. But the application data in D:\Applicaton_Data may have a different SLA, needing to be backed up once per hour. Depending on the answer to question #1, I'm envisioning two separate possibilities:

    1) If BMR treats each "critical volume" as a separate data source, then I'm concerned that I can't protect D:\Application_Data in a separate protection group from the BMR protection group. My understanding is that DPM won't let you protect the same volume in two separate protection groups.

    2) If BMR is considered a single data source, regardless of the number of "critical volumes" involved, then I think I'd be OK to protect D:\Application_Data in a separate protection group. Thus, BMR could have the once per week SLA, and D:\Application_Data could have my once per hour SLA.

    Finally, regarding your response to question #5... WSB generates a "full" system state backup locally on the server each time DPM performs a system state backup. DPM then copies this full system state backup (perhaps grabbing only block level differences) to the DPM server's replica volume. My question is: does WSB generate a "full" BMR backup with each run? Or does WSB have the concept of an incremental BMR backup with respect to DPM? I understand that DPM is grabbing only the changed bits, but nonetheless I feel that storage would be more efficient if WSB were incremental-aware.


    Tuesday, December 14, 2010 3:32 PM
  • Hi Frank,

    1. 300 data sources limit is based on Logical Disk Manager database limitations. In case of BMR DPM uses 2 volumes - one for the replica and one for the recovery point - for all "critical volumes" on protected server. So the answer is - its stored as a single data source.

    3. You can protect BMR, which includes "critical volume" in Protection Group A, and data on that critical volume in Protection Group B.

    About WSB - check out this thread http://social.technet.microsoft.com/Forums/en-US/dpmssandbmrbackup/thread/d26735ba-1309-4feb-8ae3-7a31e6c80d0a

    My DPM blog ystartsev.wordpress.com
    Tuesday, December 14, 2010 9:49 PM
  • Thank you, sir! I believe that answers my questions :)

    Wednesday, December 15, 2010 12:29 AM