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Express full backup vs Synchronization RRS feed

  • Question

  • I'm using DPM2010 to backup various items.  Curerntly, I'm backing up a few file servers, some hyper-v vm's and my exchange 2007 server.  I will be adding sql databases shortly to this.  I am trying to figure out a good schedule for my business needs.  I'm researching the difference between Express full backup and syncrhonization.

    http://technet.microsoft.com/en-us/library/ff399500.aspx

    This link describes an express full backup as:

    An express full backup is a type of synchronization in which the protection agent transfers a snapshot of all blocks that have changed since the previous express full backup (also since the most recent consistency check performed or the initial replica creation for the first express full backup) and updates the replica to include the changed blocks

    Syncrhonization is described as:

    Synchronization is the process by which Data Protection Manager (DPM) transfers data changes from a protected computer to a DPM server and then applies the changes to the replica of the protected data. DPM relies on synchronization to keep replicas synchronized with the data on the protected computers.

    Both transfer changes and apply to the replica.  Why would I want to use one over the other.  If I have a 7 day backup of a file server and run Sync's every 4 hours vs express full backups every 4 hours, what is the difference?  Sync's take less time to complete.  If I have a sync run at 12 noon and delete a file at 1pm - then another sync runs at 4pm and another sync runs at 8pm - could i restore the file after the 4pm sync and could I restore the file after the 8pm sync?  I'll pose the same question, but running express fulls at noon, 4pm and 8pm.  If I can restore the file in all scenarios, then why wouldn't i just do an initial replica and sycn's after that since sync's don't take as long as EFB?  I must be missing something here.

    Thanks for any help

    Zach


    Zach Smith
    Friday, June 18, 2010 1:55 PM

Answers

  • Hi Zach,

     

    For file data, Windows VSS Infrastructure only support 64 snapshots, that is the reason why we cannot protect disk based file data backups more than 30 days if you take two recovery points a day.  So even though we can synch as often as every 15 minutes, we cannot make RP's for them due to the VSS Infrastructure limitation for protected file data.

     

    Cheers


    Regards, Mike J [MSFT] This posting is provided "AS IS" with no warranties, and confers no rights.
    Friday, June 18, 2010 9:18 PM

All replies

  • Hello Zack,

     

    Express full backups are only conducive to data sources containing databases like Exchange, SQL and Sharepoint.   Express full backups apply block level changes to the DB files themselves, whereas synchronizations between express full backups only bring over the log files.  For DB protection, both express full and synchronization backups are recoverable from the recovery tab.  Protection of file data does not have an express full backup type, they are solely synchronizations and recovery points.  For File Data protection, only recovery points are recoverable from the recovery tab. 

     

    Hope that helps your understanding of Express Full backups.


    Regards, Mike J [MSFT] This posting is provided "AS IS" with no warranties, and confers no rights.
    Friday, June 18, 2010 4:11 PM
  • That is very helpful.  Thank you.  I do have a question regarding your last statement about File data protection recovery only uses recovery points.  If that is the case, then why, or to what benefit, is there to run sychronizations when backing up a file server?  Right now I am backing up approx 1.2 TB of files and am running a synch every 4 hours and a recovery point every 8 hours.  Why am I doing that :).  I mean, why would I want to run a sync for a file backup if I can only recover from my recovery points?

    Thanks for the help.

    Zach


    Zach Smith
    • Edited by ZachSmith Friday, June 18, 2010 6:38 PM grammar fix
    Friday, June 18, 2010 6:37 PM
  • Hi Zack,

    You get a few benefits of doing frequent synchronizations versus one right before a recovry point.

     

    1)  It''s like sipping through a straw versus drinking from a fire hose, the changes trickle in throughout the day versus one huge transfer at the end right before making a RP is created.

    2) Even though the data brought over during synchronizations is not recoverable immediatly, it can be by making a manual recovery point.  So the amount of data lost at most should a total melt down occur on the protected server would be only the data that changed between synchronizations.   So if you Synch every 15 minutes, you only have a data loss window of 15 minutes.  If you sync every 8 hours, you have a data loss window of 8 hours. 

    Hope this helps.


    Regards, Mike J [MSFT] This posting is provided "AS IS" with no warranties, and confers no rights.
    • Marked as answer by ZachSmith Friday, June 18, 2010 7:10 PM
    • Unmarked as answer by ZachSmith Friday, June 18, 2010 7:15 PM
    Friday, June 18, 2010 7:04 PM
  • Mike,

    you are worth your weight in gold my friend.  Thanks for the help.

    Zach


    Zach Smith
    Friday, June 18, 2010 7:09 PM
  • One more question Mike, then we'll remark as answered.  It makes sense what you say about doing sync's every x minutes and create a RP at the end of the day.  So why wouldnt I just create a recovery point every time I sync?  a RP and sync both only do block level changes since last backup/sync correct?  Wouln't it take the same amount of time to just create a RP every 30 minuts as compared to running a sync every 30 minutes and a RP at the end of the day?

    Thanks man!

    Zach


    Zach Smith
    Friday, June 18, 2010 7:17 PM
  • Hi Zach,

     

    For file data, Windows VSS Infrastructure only support 64 snapshots, that is the reason why we cannot protect disk based file data backups more than 30 days if you take two recovery points a day.  So even though we can synch as often as every 15 minutes, we cannot make RP's for them due to the VSS Infrastructure limitation for protected file data.

     

    Cheers


    Regards, Mike J [MSFT] This posting is provided "AS IS" with no warranties, and confers no rights.
    Friday, June 18, 2010 9:18 PM
  • Hi,

    I agree with Zach completely, the description on the Technet site is nearly identical for synchronizations and Express Full Backups.

    However thanks for the clarification.

    In the Technet section entitled "The Application Data Synchronization Process," (http://technet.microsoft.com/en-us/library/bb808837.aspx) more light is shed, which appears to contradict the link Zach posted:

    "How changes are transferred to the DPM server depends on the application and the type of synchronization. The operation that is labeled synchronization in DPM Administrator Console is analogous to an incremental backup, and it creates an accurate reflection of the application data when combined with the replica.

    During the type of synchronization that is labeled express full backup in DPM Administrator Console, a full Volume Shadow Copy Service (VSS) snapshot is created but only changed blocks are transferred to the DPM server." Therefore, a synchronization doesn't apply the changes to the replicy, it puts them alonside the replica.

    What would be great would be a webcast with DPM fundamentals - including the above points, plus short-term and long-term backup implications within the same protection group,) and another specifically for Exchange protection - disk space planning - is it really not advisable to reduce recovery point space (for example I have a 900Gb database for which I am retaining data for 7 days, with syncs every 4 hrs and a full express once a week and I requiere 2.7Tb??? - seems extraordinary) there are webcasts only for Sharepoint and SQL at this time.

    Thanks!

    • Edited by johnny mango Wednesday, July 21, 2010 10:00 PM Addition of more information
    Wednesday, July 21, 2010 5:22 AM