Hi. Firstly thanks in advance for any replies.

For some reason, like many others, I am not understanding the Synchronization function of DPM 2012.

I have a recovery point scheduled for 10PM each day on a folder. I synchronize every hour which updates the replica.

My question is when I go to recovery I only see recovery points for 10PM. None for each hour. It is also the same if I look at all possible recovery points for individual files.

When I look at the file in recovery I see a last maintained date that is 6 hours less than the actual last maintained date even though in those 6 hours 6 synchronization jobs ran and completed.

Hi,

For protected volumes or shares, including systemstate and client protection, the time of the recovery point is the time you will see under the recovery tab.  Synchronizations for file data are not recovery points.  However, with that said, if you needed to recover a file between the last recovery point, and before the next recovery pointy is created, you can manually create a recovery point and recover files from that intermediate recovery point assuming one or more synchronizations were successful in between.   

So, if you are doing synchs every 15 minutes, and the last RP was at 12:00 noon, and at 3:25pm the protected server power supply goes belly up, the last synch was at 3:15pm, so you could manually make a recovery point without synchronization, and that restore point would include file changes up to and including 3:15PM, so in essence you only lost 10 minutes worth of changes before the server became inaccessible.  The longer time between synchronizations, the more changes you miss bringing over to the DPM server and potentially lose should the protected server croak.

For file  protection Windows support 64 snapshots per volume, so based on your retention period, you could take more recovery points per day and have more recovery point times to choose from each day.   IE: 1 RP / day = 64 days max protection.   6 RP / day = ~ 10.5 days max protection.

Thanks for the reply. Could you please clarify a couple of things if possible. 

Is it possible to create a recovery point from any synchronization job?  For example if a I have a RP job that runs at 10PM and 5PM and have sync jobs every hour between. Can I create a RP from 1PM. If not then I am not understanding the point of the Sync jobs. If you can create a RP job from a sync job then why have sync jobs? Why are they all not just RP jobs? 

Also can you see what data was backed up in the sync job?  I guess not as this is not a RP job.

Sorry but still a little bit confused :-)

Hi,

It's really quite simple. A traditional backup is obsolete the second it completes. Why ?  Because files are constantly being changed, created, deleted. DPM provides the mechanism to bring those changes over to the DPM server and applied to the replica volume at specified intervals so you have additional protection in case of a failure of the protected data.   You can do the synchronization right before a recovery point, which would be equivalent to a traditional backup and your changed data is vulnerable until the next recovery point time, or you can configure DPM to perform incremental synchronizations ( as often as 15 minutes) so the replica volume on the dpm server is in sync with the protected data at more frequent intervals.   The less time between synchronizations, the better protected you are against data loss of changed or new files on the protected server.

Another way to look at incremental synchronizations is do you want to drink from a fire hose and bring the changed data over all at once a couple times a day, or drink from a straw and let it trickle over every 15 or 30 minutes.

Regardless of your synchronization frequency, you can "freeze" the replica volume at anytime by making a manual recovery point without synchronization and that most recent data becomes available as a recovery point under the recovery tab that you can restore.

hope this helps.

Hi. Thanks for the reply. The whole process is still confusing but maybe its a short vs long term backup.

I have a backup 9PM each night.

Sync jobs every hour.

At 2PM the next day a user reports that a file was deleted. How do I restore this file?  The backup from the night before has already been updated with all the sync jobs so the file has already been deleted from the replica. How can I restore the file from one of the earlier sync jobs?

Also does a constancy job update the replica with the protected file at that point in time? 

Thanks again.

Hi,

Your recovery point time was at 9:00PM the night before the file was deleted, so you simply restore the file from the 9:00PM backup.  Synchronization update the replica between recovery point times, and do not effect older recovery points.

Yes, all Synchronization and Consistency check jobs update the replica to it is in sync with the protected v

Hi Mike,

Although the post is more than one year old, I would like to reply on one point about synchronization under DPM2012 R2.

If I have the following scenario for a protected file server

I synchronize data every hour, but only take recovery points at 8am, 12pm, and 6pm. 

A user creates a file  at 8:15 am but deletes it by mistake at 10:10 am.

Let's consider 2 situations:

1. User come to see me at 10:30am  to know if I can restore the file

Although the last RP was at 8:00am, I can manually create a RP at 10:30 am. DPM will use the sync from   10am (as the file was added first to the replica during the sync of 9:00) and it will restore the file in the state in which it was at 10:00. Restore is then possible, right? The copy will be on the one at 10:0 am

2. User come to see me at 11:10am  to know if I can restore the file

In that case, on the last synch at 11:00am, DPM deleted the file from the replica as the file itself was deleted from the file server at 10:30am. Even I create manually a RP, I cannot restore the file as the file is no longer present on the replica 

Restore of the file is impossible then, right?

Last question:

As a DPM best pratice for protecting MS Clustered File Server, would you recommend to run synchronization every hour ( or every 15min)

Does it affect however network performance, disk I/O performance or system process on the protected source server and DPM server?

Regards,

Evan

Hi,

Scenarios 1 - Yes you can restore the file if you make a manual recovery point without synchronization.

Scenario 2 - correct, the file will be deleted from replica at 11:00 sync, so you can only restore the file from the 8:00AM recovery point.

As a DPM best practice for protecting MS Clustered File Server, would you recommend to run synchronization every hour ( or every 15min)

Q) Does it affect however network performance, disk I/O performance or system process on the protected source server and DPM server?

A) It really depends on how much data changes between synchronizations.  The more the data changes the more data that needs sent to the DPM Server and the longer it will take.  While a synchronization is in progress a VSS shadow copy has to be maintained on the clustered volume.  VSS copy-on-write (COW) will effect file server performance, but it all dependents on how fast the hardware is - if it's fast, then users will probably not notice it.