Troubleshooting intermittent pings

Troubleshooting intermittent pings can be a pain in the rear. Here are some steps I have used to isolate the issue.
I am working with a customer who is having a Hyper-V cluster, after getting the Network Adapters sorted out I noticed the RDP connectivity to the server was poor. A ping to the default gateway revealed high ping latency and a good handful of request time-outs.  

• Updated the drivers - No change.
• Changed the CAT6 cable - No change.
• Disabled VMQ - No change.
• Plugged my laptop in to the same cable - Same issue, Bingo! This turned out to be a red herring. I updated my drivers and plugged the power in and that resolved the laptop ping issue.
• Tried another laptop on the same cable - It was fine, 1ms.
• Tried another 1GbE NIC to eliminate the LBFO driver - still the same.
• Tried a 10GbE - Seems to be stable, odd.
• Tried another switch - Seems to be stable, odd.
• Flatted the server, installed Windows 2012 R2 again and test the ping, it was fine, odd!
• Repeated all the configuration steps one at a time each time testing the ping, still OK.
• Joined the domain, BAM! Pings all over the shop.
• Tried safe mode, Seems to be stable 1ms!
• Removed the server from the domain, seems to be stable 1ms.
• Added the server back to the domain, pings latent and intermittent again.
• Stop the Base Filter Engine (stop-service BFE - force), seems to be stable 1ms.
• Uninstall the Broadcom driver and use the OOB driver from Microsoft, seems to be stable 1ms.

Update: After creating some VMs the problem moved inside some VMs. The solution was to change the Broadcom 1GbE NICs for Intel x350-t NICs.

Hardware, Dell PowerEdge R720, 1GbE & 10GbE Broadcom NICs. Switch HP 5400

Disk performance stats are missing from task manager

By default basic disk IO stats are not available in Windows Task Manager. This counter can be useful for a quick peek at what the disk is doing. For a more detailed look you need to use Resource Monitor.

To enable the Disk statistic in taskmgr, execute this command from an elevated CMD prompt.

diskperf -y

SQL FineBuild - Optimal SQL installation script

http://sqlserverfinebuild.codeplex.com/releases/view/121215

Windows servers keep resolving to a DHCP address

Windows servers with static IP addresses randomly loose their correct DNS IP address and start resolving to some random IP address for the DHCP scope.

This happens with Windows 2012 R2 DHCP and DNS servers. When a new server is connected to the network and powered up, it get's and DHCP address from the local DHCP server. After you fix a static IP address on the new server. It PINGs and DNS resolution works correctly, resolving the new IP address.
Later, on the hour normally. The new server starts to resolve to the old DHCP address. I checked the server to make sure that no Network Adapters have "Obtain and address automatically" but they did not.

Turns out that the 2012 DHCP updates/overwrites the DNS record to match the DHCP scope.

FIX: Find the rogue address within DHCP and delete it. On the new server issue an IPCONFIG /REGISTERDNS

Configuring Dell PowerVault DR4100 with vRanger 7.1 and RDA (Rapid Data Access)

With the latest DR4100 software, version 3.1 and Dell vRanger 7.1 we can now use RDA or Rapid Data Access as a backup target.

Open the DR4100 web interface and select 'Containers' I have chosen to edit the default "backup" container but you can create a new on if you wish. 

Set the connection type to Rapid Data Access (RDA) as show below.

Next, select 'Clients' from the menu, select the RDA tab and click Edit Password in the top left.If you don't see this available, click the CIFS tab and RDA again. Seems to be an interface bug. Select the client type as RDA and enter a secure password.

Open the vRanger interface, selecting My Repositories, find Dell Rapid Data Access (RDA) at the bottom and select 'Add'

Enter a name, I have used DR4100, enter the IP address of the DR4100 on the LAN, enter the backup_user as the username and enter the password you set in the previous step.

Click OK, vRanger will check access to the DR4100 and close the dialogue box. You have finished and can now use the DR4100 as a backup target when creating a new job. I got over 200 MBps in my test backup with Hyper-V 2012 R2.

Dell PowerVault DR4100 becomes unreachable after update 3.1.0107.0

As with any installation of new hardware we should check the support website to make sure we have the latest firmware and software available.

After logging into the Dell support website there was a new update available for the DR4100 device I was installing. The patch was downloaded and the system was upgraded. The screen warns this can take a long time. After the update I rebooted the unit, unfortunately the unit was then unreachable from the LAN, I was able to gain access via the iDRAC interface.

Looking though the logs I could see that while the software had updated the firmware packages built in to the update bundle had not. This can happen if the iDRAC has started up too quickly.

The solution is to open the iDRAC console, login to the DR4100 with the 'administrator' user account and password and issue this command.

 maintenance --remote_access --racreset

After the iDRAC reboots, login to the console again and start the firmware manually.

system --upgrade

Enter the 'administrators' password and wait for the firmware to complete. After approximately 30 minutes the update should complete and ask for the restart.

system --reboot

Once the reboot has completed you should be able to access the web interface.

Opening the agent port on Hyper-V hosts form Dell vRanger software

This PowerShell command needs to be executed from one of the cluster nodes. It will find all the nodes in the cluster, and create a firewall rule to allow TCP port 8081 inbound.


get-clusternode | ForEach-Object  {Invoke-command -computername $_.name -scriptblock {netsh advfirewall firewall add rule name="Dell vRanger remote agent" dir=in action=allow protocol=TCP localport=8081}}