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Quick Way to Check DFS Replication Backlog with dfsrdiag

When DFS Replication (DFSR) falls behind, the fastest way to see how many files are waiting to replicate between two servers is the dfsrdiag backlog command. Run it from an elevated Command Prompt on a server with the DFS management tools installed.

dfsrdiag backlog /RGname:"ReplicationGroupName" /RFname:"ReplicatedFolderName" /smem:SendingServer /rmem:ReceivingServer
  • /RGname: the replication group name, for example domain.com\dir\dir
  • /RFname: the replicated folder name
  • /smem: the sending member (server name)
  • /rmem: the receiving member (server name)

The output shows the backlog count and the first files in the queue. Run it again in each direction to check both sides of the replication.

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How to Set Up Sophos UTM 9 High Availability (Active-Passive) on VMware

This guide shows how I added a passive Sophos UTM 9.x node (version 9.307006 at the time) to build a hot-standby, active-passive high availability pair. Our environment is fully virtual: VMware ESXi 5.5 (build 2456374) hosts, Force10 switches, and SAN storage. I used these exact steps across three data centers and a development environment.

1. Prepare the Primary UTM

Get your UTM set up and working the way you want first. Add a couple of extra NICs for the future and confirm basic firewall functionality. Then log in to the UTM shell as root and run:

cc set ha advanced virtual_mac 0

This step is required for HA to work in a VMware environment.

2. Clone the UTM

I use an even/odd host naming scheme, so I renamed the existing UTM to UTM01 and cloned it from vHost01 to vHost02 as UTM02.

3. Enable HA on the Primary (Node 1)

  1. Log in to UTM01 and go to Management → High Availability → Configuration.
  2. Select Hot Standby (active-passive).
  3. Choose the HA sync NIC (I used the last one added, eth7).
  4. Enter the device name (csutm01), select device node 1, and set an encryption key.
  5. Click both Apply buttons.

4. Reset the Clone to Factory Defaults

When the clone finishes, do not power it on yet. Edit the VM and disconnect every network card except the one on the HA network. Then power on UTM02, open the console, and log in as root.

Make absolutely sure you’re on UTM02, then reset it:

cc
RAW
system_factory_reset

The system powers off when the reset completes. Reconnect the internal interface, power it back on, and run through basic setup. Configure only the internal network and nothing else (you may need to add a license file).

5. Enable HA on the Secondary (Node 2)

  1. Log in to UTM02 and go to Management → High Availability → Configuration.
  2. Select Hot Standby (active-passive) and the same HA NIC (eth7).
  3. Enter the device name (csutm02), select device node 2, and use the same encryption key.
  4. Click both Apply buttons.

The web interface will lock up, showing you’ve lost the connection to UTM02. That’s expected.

6. Verify the Cluster

On UTM01, open the High Availability menu. You should see UTM01 as Active (Master) and UTM02 as Syncing. Give it about 15 minutes to stabilize.

If you run into trouble, feel free to send me a message.

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Fix iSCSI TCP Retransmits with Force10 Switches, EqualLogic, and VMware

I was seeing high TCP retransmit rates on an iSCSI SAN built on Dell Force10 switches, EqualLogic storage arrays, and VMware ESXi hosts. The fix was configuring every switch port that connects to an EqualLogic array or a vHost iSCSI NIC with jumbo frames, flow control, and RSTP edge-port settings.

Force10 iSCSI Port Configuration

config
protocol spanning-tree rstp
no disable
interface GigabitEthernet x/x
description EQL or vHost iSCSI Port
no ip address
mtu 9252
switchport
flowcontrol rx on tx on
spanning-tree rstp edge-port
no shutdown
!

What Each Setting Does

  • mtu 9252: enables jumbo frames on the port for iSCSI traffic.
  • flowcontrol rx on tx on: lets the switch and storage pause traffic instead of dropping packets.
  • spanning-tree rstp edge-port: brings the port up immediately without waiting on spanning-tree.

With these settings in place, TCP retransmits dropped below 0.05%.

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How to Enable or Disable Hibernate in Windows from an Elevated Command Prompt

Windows hibernation is controlled with the powercfg command. Turning it off frees the disk space used by hiberfil.sys; turning it on restores hibernate and hybrid sleep. Both commands need an elevated (Run as administrator) Command Prompt.

Enable Hibernate

This restores the hiberfil.sys file and brings back the “Allow hybrid sleep” and “Hibernate after” settings under Sleep in Power Options.

  1. Open an elevated Command Prompt.
  2. Type the command below and press Enter.
  3. Close the Command Prompt.
powercfg -h on

Disable Hibernate

This turns off hibernation, deletes hiberfil.sys, and removes the “Allow hybrid sleep” and “Hibernate after” settings. On Windows 8 and later it also disables Fast Startup.

  1. Open an elevated Command Prompt.
  2. Type the command below and press Enter.
  3. Close the Command Prompt.
powercfg -h off