Diagnosing Server 2008 and Windows 7 LAN Speed

networkingslow-connectionwindows 7windows-server-2008

I have a customer with Server 2008 in a VM, and maybe 15 Windows 7 clients. They are experiencing slowness when using an ERP system whose data resides on the server. The database in question is a load of shared files, as opposed to on a database server.

The network is gigabit throughout. I am told that the cabling is CAT5e or CAT6, there is some chance it may not be.

The switch is a 3Com 4200G, which is a managed device.

Initially I have used a tool called PathTest to examine raw LAN throughput. It's similar to iperf.

I ran a test between server and workstation, for 10 seconds, bidirectional. The results are:

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Firstly from client to server I'm seeing what strikes me as a low-ish Mbps number, and what strikes me as a very low number from server to client. The numbers are consistent over the 10 or so times I ran the test.

Am I right in thinking they're low and if they are, where do I start looking ?

Best Answer

Okay, the fix in this case was:

Installed Server 2008 Service Pack 2 on the Windows Server 2008 in question.
Re-enabled SMB2 on that server. It was possibly disabled originally to circumvent a known bug that caused file corruption with certain products when using Server 2008 or later with Windows Vista or later.
Installed hotfix Windows6.0-KB2635024-x86 on the server to address another file corruption bug in SMB2.
On each Windows 7 workstation, updated network drivers to most current version where needed (some were 5 years old).
On each Windows 7 workstation, configured network card to disable interrupt moderation, and force to 1Gbps full duplex.
On each Windows 7 workstation, installed hotfix Windows6.1-KB2618096-x86 to address a file corruption issue in SMB2.

Related Solutions

Unexplained slow gigabit network speeds

Try disabling Window's auto-tuning feature.

In a CMD window:

netsh interface tcp set global autotuning=disabled

Re-run your test, and see if you notice a performance improvement. I've had to do this on a couple of laptops running Windows 7 in my house, and it's helped.

If things get worse, or you don't notice any improvement, you can re-enable autotuning by:

netsh interface tcp set global autotuning=normal

Can’t add client machine to windows server 2008 domain controller

You are correct-- Active Directory has strong dependencies on DNS.

To make this easy, you should install the Microsoft DNS server onto the domain controller computer and configure it to use itself for DNS. Your ISP's DNS servers probably don't support the dynamic updates that would make life w/ Active Directory easy (and they probably won't configure a zone for your AD domain's name anyway).

You can optionally configure your ISP's DNS server as a "Forwarder" in the DNS server you run to allow queries your DNS server can't answer to be sent on to your ISP, but the Microsoft DNS server will resolve queries to the root DNS servers in its "stock" configuration. Not using your ISP's DNS server really isn't a big deal, though.

Configure the machines that you'd like to join your domain to use your domain controller's DNS server as their only DNS server. Don't specify any other DNS servers on any of the machines. They should be using your Microsoft DNS server's IP address as their exclusive DNS server.

That'll get you over the problem of not being able to join your other machines to the domain. Be sure, when you try to join the domain from these machines, that you specify the fully-qualified domain name (and, if necessary, check with "nslookup" to see that they can resolve the domain's name to an "A" record that refers to the domain controller computer). If you've tried several times and it's still not working you may want to flush the DNS cache on the machine you're trying to join by running an "ipconfig /flushdns" from an elevated command-prompt.

You can use whatever name you want for your Active Directory domain's DNS name. Only your servers will be using a DNS server that "knows about" your domain, so you can choose any name you want. Bear in mind that your DNS server is going to be "authoritative" for that domain. If you choose "microsoft.com" as your Active Directory domain name, for example, your domain-member computers won't be able to resolve "real" names in the "microsoft.com" namespace (since your DNS server will think that it "owns" the "microsoft.com" domain).

I recommend that you either use a subdomain of a domain name you already own, like "ad.company.com", or that you use a domain with the ".local" suffix (some people say that using ".local" isn't "proper" since no RFC calls it out as being reserved). I prefer the "ad.company.com" style names. It looks like you've already installed AD, though, so your name choice is somewhat "set". (It's possible to rename a domain, and not really too difficult, but in this case it might be better to uninstall and reinstall AD.)

Best Answer

Related Solutions

Unexplained slow gigabit network speeds

Can’t add client machine to windows server 2008 domain controller

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