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W_Harrison's avatar
W_Harrison
Level 4
9 months ago

How resilient is the off site copy for System Recovery

Hi All,

We are using the FTP offsite function with System Recovery and am curious as to how resilient this feature is. In so much as keeping the 'local' and off site files in sync and what happens if there is an interruption in the process?

In our case, Interruptions could be down to an internet failure, vpn tunnel or even a server restart. What mechanics, if any does SR use to check that what's been copied is good. (but more importantly, what does it do if things are 'out', files missing etc.)

What I have noticed is that the Offsite copy can sometimes take a while to actually kick in after an incremental job has finished, I've also noticed that on occasion some of the remote files are actually bigger in size than the original. (we have compare scripts that check file names match as well as sizes).

Thanks

Wayne.

8 Replies

  • The offsite copy is to synchronize between the primary location and offsite copy location.
    So if the offsite copy fails with any reason, System Recovery will try synchronizing again after the next backup job finishes. The success of the offsite copy means the recovery point files in the primary location are completely copied to the offsite copy location.

    • W_Harrison's avatar
      W_Harrison
      Level 4

      If I understand this correctly then, SR will check that all files that are on the primary site are copied to the remote site each time a backup is ran, and copy over anything that it sees 'missing' - which is good. Likewise it should also remove any 'extra' files (typically image sets that are removed when they expire when you are only 'keeping' 3 sets).

      Following on from that, how detailed is the check? I've seen files that are larger on the remote copy than on the source, will it check against file size matches also or just the existence of a file called the same name? And following on from that, if a file did get interrupted during a copy, then it is also likely that the remote file could be smaller, will it copy the whole file or attempt to see what is 'missing'?

      Ultimately is there any hash check against each file to make sure that they are indeed the same?

      Thanks again
      Wayne.

      • akihiro1's avatar
        akihiro1
        Moderator

        As far as I know, SR checks the hash values between primary location and offsite copy location when offsite copy starts. If the file size is different from the primary location, the file is copied to the offsite copy location.
        Also, the file is copied to the offsite copy location when the hash value is different even if the file size is complete the same between primary location and offsite copy location.

        Actually I tested this. So the resilience of the offsite copy is strong.