Can I use Microsoft DFS-R function as an incremental backup ?

Posted on 2011-10-21
Last Modified: 2012-05-12
Can DFS-R backup incremental or differencial data on a block or bit based level ? That means that if a certain part of files changes, only the incremental changes are replicated and not the entire file.
I want to use this function for big one file backup.

Is it possible for DFS-R?
Question by:shouichi
    LVL 12

    Expert Comment

    DFS-R does keep track of changes that the block level, but not disk block-level (

    The file must be larger than 64KB for this to take effect and you must have a non-Standard edition of Server to benefit by this on at least one of your DFS members.

    Depending on how you configure DFS, it is possible to have one of the member shares not accessable by any user and you can do one-way replication, but this won't serve as a 'backup' because legal deletes and overwritting saves will be replicated to your 'backup'.
    LVL 4

    Expert Comment

    Hi Shouichi,

    I would not suggest using DFS as a backup method. As sommerblink mentioned above DFS will replicate unwanted changes as well. Instead I would suggest that you configure VSS Shadow copy on your data server as use this as your during the day backup method with an incrimental backup at night using an actual backup application.
    LVL 12

    Expert Comment

    Actually just realized that a bit of my copied text didn't make it in on my first post... and that is to think of DFS as RAID for your network shares.

    You would never consider RAID to be a backup. It just provides fault tolerance and redundancy to your storage.

    But let me know if I've misunderstood what your intentions are. Perhaps a little more elaboration would be helpful.

    Author Comment

    Thank you for information.

    What I want to do is to backup pst file.
    1.  I will backup all employee's microsoft outlook pst  files on the file server
    2.  and then,  backup these files to strage server. ( disk to disk backup)
    3.  finally, Tape AutoLoader will be connected to Storage server , tape backup will also be taken.

    These outlook pst files would become up to 5 Tera Byte totally in the future, therefore I consider it is better to backup only incremental by using DFS-R for daily backup.

    Raid must be configured on File server and storage server.

    In these senario, what kind of backup solution would best for me ?
    I don't want to take much time to backup full data, that is why I am considering DFS-R , VSS or what kind of solution would be useful for incremental or differencial backup of pst files ?

    LVL 12

    Accepted Solution

    DFS doesn't do 'incremental' backups. It can do 'incremental' replications, only moving over the changes across the wire, versus the entire file. Also, it is only available on Windows Servers. Desktop operating systems do not support DFS in this sense.

    What you probably need to get is a solid backup program. I am partial for Symantec Backup Exec. Since you're already talking about a robotic tape drive, do you already have backup software?

    I’m assuming that these files are local to the computer? I would use a batch file that would run on a schedule (or whatever makes sense based on your power policies) to drop the PST to a fileserver. This should happen at some point prior to your PST backup job (next step).

    Once the files are moved over to a fileserver, with for example Backup Exec, I would then set a job that will take the PSTs that were copied over and then back them up to the tape drive.

    But I understand that you’re concerned about total backup size, all the backup programs that I am familiar with do not understand the ‘pst’ file format. They will simply identify that the file has updated since the last backup and will back up the full pst file again.

    A matter of personal opinion here: But if you plan on having 5TB of PSTs, there is a far better solution to your email problem and related backup problem: Microsoft Exchange. It sounds like you have plenty of users (or at least plenty of email) and something like this will not scale well, since once per day you’re going to have 5TB of PSTs come from your desktop/laptop users to a file server, which will saturate your network during that time.

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