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Exchange 2016 - Lagged copy and backup + Circular Logging RRS feed

  • Question

  • Hello,

    We are deploying a new Exchange 2016 infrastructure, with:

    • 6 servers
    • 3 copy of databases: one active, one passive, one lagged
    • Weekly backup the passive copies with Veeam

    Our initial target was to follow the Preferred Architecture, but we don't respect the minimal recommendation of 2 datacenters and 4 copies of data.

    We still went for one lagged copy, as from what we understood could protect against bad database corruption that would spread on active + passive. For safety, we kept a cold backup (Veeam) as all our servers/storage in on same datacenter.

    On Internet we read that circular logging are bad, because you cannot restore data between your backup AND current time of issue on an Active/Passive copy. 

    > Indeed this makes sense, but as soon as you have lagged copies, does it still makes sense?

    For us the benefit of Circular Logging is constant "freeing" of logs space on Active and Passive DB, plus sometimes a backup can fail and not do the rotation for more than a week.

    Looking forward for your opinions/advice!

    Thanks,

    Thursday, April 26, 2018 1:10 PM

All replies

  • Hi,

    Please note that:
    1. Lagged copy is a passive copy in a DAG.
    2. Circular logging applies to the database, not whether its active or passive. If you enable it, it applies to all the copies of that database.

    Also, the circular logging is not recommended in a product environment because we cannot recover any data more recent than the last full backup without a complete set of transaction log files. Instead, we can use backup plan to take care of log truncation.
    Ps: Yes, you enable circular logging on database base on your requirement.

    More information about it, refer to: Circular Logging and Mailbox Database Copies

    Best Regards,
    Allen Wang


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    Friday, April 27, 2018 8:48 AM
    Moderator
  • Hello Allen,

    Thanks for your reply.

    I'm aware that the circular logging applies to all the copies.

    Nonetheless, when you have a Lagged copy, the logs stays for the delay you specified.

    So in our case:

    • Weekly backup
    • 7 days delay for the lagged copy
    • Circular logging: the logs replays on the Active and Passive copy, but we can still see logs up to 24/04/2018 (as of today) in the DB folder of the lagged copy.

    If we have an issue in the Active copy / Passive Copy, we still have 7 days of log files on the lagged copy, so we can use those ones to make more granular / close to now recovery?

    Regards,


    • Edited by JLRouzies Wednesday, May 2, 2018 11:28 AM typo
    Wednesday, May 2, 2018 9:14 AM
  • Yes, it seems fine.

    Best Regards,
    Allen Wang


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    Tuesday, May 8, 2018 3:23 AM
    Moderator
  • Yes, It will be fine. You no need backup also. as a lagged copy will have 7 days logs.

    Shyam

    Monday, October 29, 2018 2:18 AM