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Domain Controller in Azure - Best practice - Extra disc with host cache turned off for AD Database, SYSVOL & Logs?

Leakim79 41 Reputation points
2020-10-08T17:10:58.437+00:00

Hello,

I would like an answer to what is the best practice for creating domain controllers in Azure regarding write cache.
After searching the internet I have found many guides that instructs you to create an extra disc with host cache set to OFF.
According to these guides this is where you should place the AD Database, SYSVOL & Logfiles when you create you domain.
On the other hand many guides do not mention this at all and after speaking to my senior colleague about this he was like "Meh" and do not bother with details like this.

So to my question:
What is best practice in this case? What are the risks of leaving the above on the standard disc with write cache enabled?

Azure Virtual Machines
Azure Virtual Machines
An Azure service that is used to provision Windows and Linux virtual machines.
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  1. Andreas Baumgarten 123.6K Reputation points MVP Volunteer Moderator
    2020-10-08T18:28:54.397+00:00

    It is best practice to use an extra disc with host cache disabled for the NTDS.dit and SYSVOL for DCs.

    With host cache on it could last, if i remember right, up to 15 minutes until the cache is written back to the disk.
    If the host has any trouble you might loose up to 15 minutes of AD related changes.
    After the VM is running again you might get trouble with different update sequence numbers on the domain controllers in AD in an AD replication scenario.

    So i would recommend the best practice for DCs with the second disk and disabled host cache. Depending on the size of the NTDS.dit and SYSVOL the additional costs of a 8 or 16 GB disk should not be a problem.

    Maybe this is helpful.

    Regards
    Andreas Baumgarten

    (Please don't forget to Accept as answer if the reply is helpful)

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