Server

A customer of mine is currently refreshing his branch office server infrastructure. A part of this project is to demote the Active Directory Domain Controllers, that are currently running in each branch office. The customer has multiple branch offices and each branch office has an Active Directory Domain Controller which is acting as file-/ print- and DHCP server. Each branch office has its own Active Directory site. The Domain Controller and the used IP subnets are assigned to the corresponding AD site. Due to this configuration the clients at the branch office choose the site-local Domain Controller as logon server. This works totally flawless since a couple of years. Over the year bandwidth of site connection has increased and even small branch offices have a redundant MPLS connection to the HQ. And no one likes single domain AD forests with 20 or more Domain Controllers…

In my last blog post I have highlighted how HAProxy can be used to distribute client connections to two or more servers with Exchange 2013 CAS role. But there is another common use case for load balancers in a Exchange environment: SMTP. Let’s take a look at this drawing:

The inbound SMTP connections are distributed to two Mail Transfer Agents (often a cluster of appliances, like Cisco IronPort or Symantec Messaging Gateway) and the MTAs forward the e-mails to the Exchange servers. Sometimes the e-mails are not directly forwarded to the Exchange servers, but to mail security appliances instead (like Zertificon Z1 SecureMail Gateway). After the e-mails have been processed by the mail security appliances, they are forwarded to the Exchange backend. Such setups are quite common. If a load balancer isn’t used, the MX records often point to the public IP address of a specific MTA. In this case, two or more MX records have to be set to ensure that e-mails can be received, even if a MTA fails.

Today I changed the SCSI controller type for my Windows VMs in my lab from LSI SAS to PVSCSI. Because the VMs were installed with LSI SAS, I used the procedure described in VMware KB1010398 (Configuring disks to use VMware Paravirtual SCSI (PVSCSI) adapters) to change the SCSI controller type. The main problem is, that Windows doesn’t have a driver for the PVSCSI installed. You can force the installation of the driver using this procedure (taken from KB1010398):

A discourse is going on in the community. I can’t say who has started the discourse, but the number of blog postings to this discourse is an indication for the interest at this topic. But what’s the topic?

Homelabs

A homelab is the datacenter of the poor man. Some people have the luck to use a fully populated data center for test and study purposes. Our job requires to work with the latest technology and products, so we need an environment for test- and study purposes. Back in the days it was sufficient to have some VMs on you computer or laptop. But as virtualization moved into the data center, it was necessary to have this in the lab. At this point homelabs began to explode.