Tag: dfs

On Monday I had the privilege of participating in an unplanned recovery drill after maintenance on our site UPS and generator tripped over itself (four times). Needless to say, a lot of our infrastructure doesn’t take too kindly to unexpected darkness, and its lack of choreography means that things come up out of order. But that’s not the focus here, just the context. Most everything was restored in relatively short order thanks to good documentation of this nature:

  1. Confirm power is reliable and not likely to fail again in the immediate future
  2. Power on network switches (core, rack, etc)
  3. Power on storage array(s) (HP, EMC, etc)
  4. Power on virtualization hosts (ESXi, Hyper-V)
  5. Connect to each virtualization host directly (vSphere Client to hostname / RDP to Hyper-V Console)
  6. Confirm presence of all storage (LUNs, datastores, CSVs)
  7. Confirm recognition/identities of hosted virtual machines (out-of-order boot may see VMs as “unknown”)
  8. If any storage is missing or VMs “unknown”, reboot hosts to confirm storage accessibility
  9. If VMs auto-power on, force power off to prevent incorrect boot order (i.e. VMs on before Active Directory)
  10. Power on Active Directory servers
  11. Reboot AD servers (one at a time) until they come up smoothly, recognize network (as “domain network”), and serve DHCP, DNS, etc
  12. Power on vCenter and VMM servers
  13. Power on DFS and shared file servers
  14. Power on System Center Operations Manager server to begin monitoring
  15. Power on load balancers
  16. Etc…

Back on topic, this post is about DFS-R (Distributed File System Replication), mentioned in Step 13, and only fully understood in this context today. I probably should have known this by now, but there’s a reason why Step 13 isn’t enough to get DFS-R operational. It catches me by surprise every time when someone reports that data is out of sync, and probably every time since, I’ve had to manually re-sync the data before doing an authoritative sync because some data comes from each side. Finally today, I know why and how to fix it.

Microsoft Technology