Friday, 21 December 2012

Correctly configuring a Dell MD3 iSCSI array

Windows 2003 r2
http://en.community.dell.com/techcenter/storage/w/wiki/mpio-to-powervault-md3000i-with-microsoft-iscsi-initiator.aspx

Windows 2008 r2
http://paulgrevink.wordpress.com/2012/02/21/configure-dell-md3000i-mpio-with-windows-2008-r2/

ESXi 4.1
http://i.dell.com/sites/content/shared-content/data-sheets/en/Documents/VMware_ESX_4-1_Deployment_Guide_for_PowerVault_MD32x0i_MD36X0i.pdf

ESXi 5.x
http://i.dell.com/sites/content/shared-content/data-sheets/en/Documents/PowerVault_MD_iSCSI_Deployment_Guide_for_VMware_ESX50_Server_Software.pdf

Array Tuning Best Practices - Dell
http://www.dell.com/downloads/global/products/pvaul/en/powervault-md3200i-performance-tuning-white-paper.pdf

High Performance Storage Tier
http://www.dell.com/downloads/global/products/pvaul/en/high-performance-tier-implementation-guide.pdf

(found under Storage Array - Change - Cache Settings) I'm reading that for sequential workloads, use 32K, and for Random, use 16K. For mixed, try starting at 16K. I believe this can be changed on the fly. I think the default is 4KB.

VMware vSphere Best Practices

http://vmwaremine.com/vmware-vsphere-best-practices/

Tuesday, 11 December 2012

Allow ICMP though Windows 2008 r2 firewall

By default the Windows 2008 r2 firewall blocks PING / ICMP, this command can used to allow ICMP through the windows firewall via an elevated command prompt.

netsh advfirewall firewall add rule name="All ICMP V4" protocol=icmpv4:any,any dir=in action=allow

Monday, 3 December 2012

Firmware updates for Dell servers running ESXi


Here are good step by step video demo of how to apply updates from USC repository manager and from USB key:

Dell Repository Manager - Creating a Bootable ISO

If you want to update all components and don’t have internet access (to access ftp.dell.com) you can download the whole repository on a USB device.

Updates using USB with Lifecycle Controller

Friday, 30 November 2012

Dell OMSA LiveCD download for ESX firmware patching

When you need to apply firmware update to a Dell server and the Life Cycle controller isn't playing ball or the server doesn't have a Life Cycle Controller you can download and use the Dell OMSA LiveCD. It's a bit bloaty for a firmware update platform.

http://linux.dell.com/files/openmanage-contributions/

7.1 seems to be the latest.

http://linux.dell.com/files/openmanage-contributions/omsa-71-live/OMSA71-CentOS6-x86_64-LiveDVD.iso

Tuesday, 20 November 2012

Dell PowerConnect 7024 stack reload time

It took 01:33 for traffic to start flowing over the stack after a reload. Usefull for calculating outages in iSCSI environment.

Tuesday, 6 November 2012

Some thoughts on interrupt moderation


Most 1GbE or 10GbE Network Interface Cards (NICs) support a feature called
interrupt moderation or interrupt throttling, which coalesces interrupts from the NIC
to the host so that the host does not spend all its CPU cycles processing interrupts.
However, for latency-sensitive workloads, the time that the NIC delays the delivery
of an interrupt for a received packet or for a packet that has successfully been sent
on the wire, is time adding to the latency of the workload.
Most NICs also provide a mechanism, usually with the ethtool command, to
disable interrupt coalescing. VMware recommends to disable physical NIC interrupt
moderation on the VMware ESXi™ host as follows:

# ethtool -C vmnicX rx-usecs 0 rx-frames 1 rx-usecs-irq 0 rx-framesirq 0

Where vmnicX is the physical NIC as reported by the ESXi command:

# esxcli network nic list

You can verify that your settings have taken effect by issuing the command:

# ethtool -c vmnicX

Note that although disabling interrupt moderation on physical NICs is extremely
helpful in reducing latency for latency-sensitive virtual machines, it can lead to
some performance penalties for other virtual machines on the ESXi host, as well as
higher CPU utilization to deal with the higher rate of interrupts from the physical
NIC.
Disabling physical NIC interrupt moderation can also defeat the benefits of Large
Receive Offloads (LRO), because some physical NICs (such as Intel 10GbE NICs)
that support LRO in hardware automatically disable it when interrupt moderation is
disabled, and the ESXi implementation of software LRO has fewer packets to
coalesce into larger packets on every interrupt. LRO is an important offload for
driving high throughput for large message transfers at reduced CPU cost, so this
trade off should be considered carefully. Additional details are available in the
knowledge base article, Poor TCP performance can occur in Linux virtual machines
with LRO enabled: kb.vmware.com/kb/1027511.

If the ESX host is restarted the above configurations must be reapplied.

Tuesday, 16 October 2012

Dell Blade IOM back door console access

There are three ways to manage a Dell Blade switch.


  1. The good old serial console
  2. SSH if you have configured the switch with an IP address via method 1.
  3. SSH to the CMC IP address with putty, teraterm etc.
    at the $ prompt type:
    $ connect switch-1
  4. To exit type CTRL+\
Magic console access to the switch for a remote location without a serial connection, great if you assign the wrong VLAN like I did and get cut off from the switch via SSH :P

switch-1 = A1
switch-2 = A2
switch-3 = B1
switch-4 = B2
switch-5 = C1
switch-6 = C2

Wednesday, 3 October 2012

Dell servers stuck at Initializing firmware interfaces...

I have seen a number of 12G Dell servers getting stuck after POST with the message below.



If you leave the server long enough it does move on. I have seem this take 45 minutes!!!
Dell PS are aware of the problem which seems to mainly effect, but not limited to blades with quad port mezz cards.
I have fixed this for one customer by using the lice cycle controller to update all the firmware, but the next site I saw this the firmware didn't work.
The work around seems to be to enter the Life Cycle controller and under the iDRAC setting untick "Collect hardware inventory on boot"

Update: Doing so stops m1000e BIOS profiles from working! Dell state they are having a lot of calls over this and are working towards a fix.

Monday, 1 October 2012

Force10 - % Error: Port is in Layer-2 mode

When you try to configure ports on a Force 10 switch for a LAG the switch throws this error:


% Error: Port is in Layer-2 mode Gi 0/xx

To prevent this issue the command

# no switchport

If the no switchport command gives the error below:

% Error: Port has Layer-2 config on it Gi 0/xx

 You will need to remove the spanning tree configuration for that port with this command.


#no spanning-tree rstp edge-port

Don't forget to save the running config ;)

Tuesday, 25 September 2012

Troubleshooting excessive I/O on a LUN in VMware


If you notice a lot of I/O being generated on a particular LUN. How do you figure out who / what is causing this? Well it is not as difficult as you think it would be…
  • Open up esxtop
  • Go to the “Device” view (U)
  • Find the device which is causing a lot of I/O
  • Press “e” and enter the “Device ID” in my case that is an NAA identifier so “copy+paste” is easiest here
  • Now look up the World ID under the “path/world/partition” column
  • Go back to CPU and sort on %USED (press “U”)
  • Expand (press “e”) the world that is consuming a lot of CPU, as CPU is needed to drive I/O

Friday, 17 August 2012

EqualLogic Auto-Snapshot Manager Agent fails to start

EqualLogic Auto-Snapshot Manager Agent fails to start on Windows hosts that are not connected to the internet. This happens because the Host Intergration Toolkit 4.0 uses .NET 2.0.
Each time a .NET application starts, it tries to check revoked certificates at crl.microsoft.com because the server has no internet access the service times out while waiting.

The solution is to increase the ServicePipesTimeout value in the registry.


The Service Control Manager will generate an event if a service does not respond within the defined timeout period (the default timeout period is 30000 milliseconds). To resolve this problem, use the Registry Editor to change the default timeout value for all services.
  • In the Registry Editor, click the registry subkeyHKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control
  • In the details pane, locate the ServicesPipeTimeout entry, right-click that entry and then select Modify.Note: If the ServicesPipeTimeout entry does not exist, you must create it by selecting New on the Edit menu, followed by the DWORD Value, then typing ServicesPipeTimeout, and clicking Enter.
  • Click Decimal, enter the new timeout value in milliseconds (I prefer 120000), and then click OK.
  • Restart the computer.

This can also be caused if the installation of the HIT 4.0 fails to install the Microsoft MPIO feature. The solution is to uninstall the HIT, reboot, manually install the MPIO feature and then install the HIT again.

see support.microsoft.com/kb/824344 for further reading.

Wednesday, 1 August 2012

Converging 10GbE and 1GbE networks with Force 10 and Dell PowerConnect

Customers are now moving from 1GbE iSCSI storage to 10GbE. This introduces a new challenge of converging 1 and 10 networks.  In this situation the customer has two existing EqualLogic 1GbE Arrays connected to a pair of Dell PowerConnect 5424 switches, these switches where joined together via a 2Gb LAG. The customer has purchased two new 10Gb Arrays and a pair of Dell Force 10 s4810 switches, but needs to have a period where the existing ESXi servers need to continue accessing the array.

The end solution:




Parts required:

4 x PowerConnect SFP Transceivers, Dell part number 0HHM9W
4 x Force10 SFP Transceivers, Dell part number 0GF76J
4 x LC-LC Multi-mode Optical Cables, depicted in blue above.

Twin-axe cables from the s4810 ports to the SFP combo ports do not work!! The answer is to use a Or if you are using PowerConnect 62xx series you need to use:

1 x Dell PowerConnect 622xx/M6220 Dual Port SFP+ module, Dell Part number 409-10135
2x 10GbE SFP+ Direct Attach copper cable 5M-KIT (Either or) Dell Part number 470-12823
2x 10GbE SFP+ Direct Attach copper cable 2M-KIT (Either or) Dell Part number 470-12822

Configuration on both PowerConnect switches:

Break the 2 port LAG between the PowerConnects, insert the SFP modules into to SFP ports 23 and 24 making sure the shared Ethernet ports aren't in use!

#conf
(config)#interface port-channel 1
(config)#desc Force10-link
(config)#port jumbo-frame
(config)#flowcontrol on
(config)#switchport mode trunk
(config)#switchport trunk allowed vlan add 100 (the iSCSI vlan)
#exit

#conf
(config)#internet range ethernet g23-24
(config)#channel-group 1 mode on (Must be ON not auto/active)

On the Force10 switches, update the firmware, stack the switches and issue these commands to create two port channels, two are required because the PowerConnect 5424's can't be stacked:

interface Port-channel 1
 description "LAG to bottom 5424"
 no ip address
 mtu 12000
 switchport
 channel-member TenGigabitEthernet 0/46
 channel-member TenGigabitEthernet 1/46
 no shutdown
interface Port-channel 2
 description "LAG to top 5424"
 no ip address
 mtu 12000
 switchport
 channel-member TenGigabitEthernet 0/47
 channel-member TenGigabitEthernet 1/47
 no shutdown

Now that the LAG between the 5424 switches and the F10's has been created we need to tell the VLANs that the traffic can pass across the LAG. The Force 10 was configured with two VLANs to match the 5424's, vlan 100 for iSCSI and vlan 101 for vMotion. The lines in bold are in important ones.

interface Vlan 100
 description iSCSI
 name iSCSI
 ip address 192.168.10.251/24
 tagged Port-channel 1-2
 untagged TenGigabitEthernet 0/0-23 (top switch)
 untagged TenGigabitEthernet 1/0-23 (bottom switch)
 no shutdown
interface Vlan 101
 description vMotion
 name vMotion
 ip address 192.168.11.251/24
 tagged Port-channel 1-2
 untagged TenGigabitEthernet 0/24-31
 untagged TenGigabitEthernet 1/24-31
 no shutdown
!

Test the LAG by pinging IP addresses on both sets of switches. Don't forget to copy the running-config to startup-config on all the switches. As a note the LAG did not work the first time , I had to remove the channel members with these commands:

no channel-member TenGigabitEthernet 0/46
no channel-member TenGigabitEthernet 0/47
no channel-member TenGigabitEthernet 1/46
no channel-member TenGigabitEthernet 1/47
Once I re-added the ports back the LAG sprang into life! Dell tech said they had seen this before!


Friday, 13 July 2012

Plug N Play errors after firmware updates

After using the Life-cycle controller on a Dell R710 I got this error. Also the server would not boot as it could not find the RAID controller.



The fix was to disable the ROM option, highlighted below for all non on-board Broadcom NICs. In my case there where eight to configure as there where 2 quad port PCI-e cards.



Tuesday, 26 June 2012

iSCSI Throughput and SMB signing

Here is an interesting article on the effects of SBM signing on iSCSI targets.



Basically it involves, disabling SMB signing on client and server communications to speed up network throughput.


http://www.thatcouldbeaproblem.com/?p=72

Monday, 28 May 2012

Remove the Exchange 2010 default Mailbox store


The First database contains the SystemMailboxes which are the Arbitration mailbox(es).
We have to move these system mailboxes to another database before of remove the Default Database.

1. Find the Arbitration Mailbox using the Exchange MAnagement Shell (EMS):
Get-Mailbox | Where {$_.Name -like "Discovery*" } | ft Name
You might need to move the Federation Mailbox also...
Get-Mailbox -Arbitration | ft Name
2. Now create a new move request in order to move the system mailboxes to another mailbox database:
New-MoveRequest -Identity "SystemMailbox{yourGUID}" -TargetDatabase "dbxxxx" 
New-MoveRequest -Identity "DiscoverySearchMailbox{yourGUID}" -TargetDatabase "dbxxxx"  
New-MoveRequest -Identity "FederatedMail{yourGUID}" -TargetDatabase "dbxxxx"
3. Verify whether the move request completed:
Get-MoveRequest
4. Now remove the move request
Remove-MoveRequest -Identity "the name of the request like Microsoft Exchange Approval Assistant"
Or clear the lot...
Get-MoveRequest | Remove-MoveRequest 

Friday, 20 April 2012

ESXi 5 EqualLogic best practices.

If you are using Raw Device Mapped (RDM) disks in your VM's, make sure the pathing for that is changed to RR and IOPs 3 as well.  (MEM would also set this connections up properly as well)
Other common tweaks are disable DelayedACK  (its in the iSCSI initiator properties) and disable Large Receive Offload (LRO)
Within VMware, the following command will query the current LRO value.

# esxcfg-advcfg -g /Net/TcpipDefLROEnabled
To set the LRO value to zero (disabled):

# esxcfg-advcfg -s 0 /Net/TcpipDefLROEnabled
NOTE: a server reboot is required.

Info on changing LRO in the Guest network.

ESXI v5.0 should also have the Login Timeout changed to 60 seconds.  (default is 5).  However, you have to be at build 514841 or better.  
See VMware KB 2007680 kb.vmware.com/.../2007680

One more common enhancement that gets missed often is creating a virtualized SCSI adapter for each VMDK (or RDM) in each VM.  (Up to 4x controllers)     If you look in the VM settings, each VMDK/RDM shows a "Virtual node"  
It will say 0:0, for first drive, then 0:1, 0:2, etc...   Shutdown the VM, change the other VMDK/RDMs from 0:1 to 1:0, then 0:2 to 2:0 and so on.   This will tell ESX to create new SCSI controllers for each disk.  Really helps with Exchange/SQL/Sharepoint.   Things that have databases and logs or fileservers that have multiple VMDKs/RDMs
*************************************************************************************
*** Script to change EQL volumes to RR and set the IOPs to 3 in ESXi v5.0. ****
*************************************************************************************
This is a script you can run to set all EQL volumes to Round Robin and set the IOPs value to 3.  (Datastores and RDMs)

#esxcli storage nmp satp set --default-psp=VMW_PSP_RR --satp=VMW_SATP_EQL ; for i in `esxcli storage nmp device list | grep EQLOGIC|awk '{print $7}'|sed 's/(//g'|sed 's/)//g'` ; do esxcli storage nmp device set -d $i --psp=VMW_PSP_RR ; esxcli storage nmp psp roundrobin deviceconfig set -d $i -I 3 -t iops ; done
After you run the script you should verify that the changes took effect.

#esxcli storage nmp device list

Thursday, 12 April 2012

Equallogic ASM/ME - Replication partner Not Available

ASM/ME reports Replication Partner Not Available. Even though manual replication works.

Issue was caused by the inability to access the VSS-CONTROL LUN on the replication partner. In my case the vssadmin username and password where correctly specified but the iSCSI initiator refused the login to the VSS LUN. The workaround is to set the VSS access at the group level to unrestricted while Dell investigate.


UPDATE. - Workaround from Dell PS.

Highlight the VSS-Control Volume and click connect you get an Advance button, Click it and you will get a pop up window and you should see your chap credentials there.
Enter you chap Credentials on both the hosts and that should resolve the issue.





Wednesday, 4 April 2012

Optimal iSCSI NIC settings

This can help eliminate TCP retransmits between EQL and the host.Find the 2x iSCSI NICs in the registry, only change this for NICs connecting to iSCSI storage.

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\Interfaces


Create two new DWORDS



TcpAckFrequency = 1
TcpDelAckTicks = 0

Restart the server.

Tuesday, 3 April 2012

Dell Life cycle controller crashes with Hardware Exeception

When you press F10 to access the Dell Life Cycle controller it crashes with this error.


!!!! x64 exception type - 00000000000000000000000D !!!!


This happened to me after using the life cycle controller to update all the firmware within the server.


The solution




Monday, 26 March 2012

vCenter server service won't start event id 1000

I was at a customer the other day. We needed to reboot the VC VM the customer hadn't done this in ages, and typically , after the reboot the vCenter server service wouldn't start, I check the eventvwr and found event id 1000. After some Googling I would appear that something was already running on port 80. I checked the VPXA logs in this location %ALLUSERSPROFILE%\Application Data\VMware\VMware VirtualCenter\Logs\ and found this error:


[VpxdReverseProxy] Failed to create http proxy: Resource is already in use: Listen socket: :80 


Futher Googling suggested either IIS has been installed, or the SQL reporting service was installed. Some reports suggest that WinRM takes port 80 but this was later found to be incorrect.


I even tried upgrading the customer the vCenter 4.1 U2 this still did not work.


NETSTAT -ANO reported that java.exe was taking the port so I presumed that Tomcat was stuffed.


Fix: In the end I thought I would stop some services to see if that was the cause. Sure enough when I stopped VMware Update Manager, port 80 was then free. I set the VUM service to delayed start and this sorted the issue. A couple of reboots proved this worked! What I can't work out is that know one else had blogged this issue.


Troubleshooting.
http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1015101
http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1003971

IOP values for harddisks

Device Type IOPS Interface Notes
5,400 rpm SATA drives HDD 50-80 IOPS SATA 3 Gb/s
7,200 rpm SATA drives HDD 75-100 IOPS SATA 3 Gb/s
10,000 rpm SATA drives HDD 125-150 IOPS SATA 3 Gb/s
10,000 rpm SAS drives HDD 140 IOPS SAS SAS is full duplex
15,000 rpm SAS drives HDD 175-210 IOPS SAS SAS is full duplex

In a mirrored configuration:
Disk IOPS = Read IOPS + (2 * Write IOPS)
In a parity (RAID5) configuration:
Disk IOPS = Read IOPS + (4 * Write IOPS)

Example calculations

Now let's look at an example. If you estimate that you need to support 40 Read IOPS (40 reads/sec) and 80 Write IOPS (80 writes/sec).
If you want to use a mirrored configuration of drives:
Disk IOPS = Read IOPS + (2 * Write IOPS) = 40r/s + (2 * 80w/s) = 200 Disk IOPSUsing 7200 rpm drives, you need: 200 / 50 = 4 disk drives
Using 10k rpm drives, you need: 200 / 130 = 2 disk drives (always round up)
If you want to use a parity (RAID5) configuration of drives:
Disk IOPS = Read IOPS + (4 * Write IOPS) = 40r/s + (4 * 80w/s) = 360 Disk IOPSUsing 7200 rpm drives, you need: 360 / 50 = 8 disk drives (always round up)
Using 10k rpm drives, you need: 360 / 130 = 3 disk drives

An excellent article on how how RAID levels effect IOPS 
http://skabelka.com/node/125
http://sudrsn.wordpress.com/2010/12/25/iops-raid-penalty-and-workload-characterization/

Monday, 27 February 2012

Wednesday, 22 February 2012

vSphere 5 Networking Bug Affects Software iSCSI

I have been hit by this issue a few times how, and doubted my skills thinking such a fundamental bug would not exist in VMware vSphere 5


Incorrect NIC failback occurs when an unused uplink is present

Joshua Townsend has blogged about this.


http://vmtoday.com/2012/02/vsphere-5-networking-bug-affects-software-iscsi/

Friday, 27 January 2012

ESXi 5.0 Dell PERC 6i Health Status Monitoring

http://blog.rebelit.net/?p=283
http://blog.rebelit.net/?p=324

Dell UPS shut down software for ESXi installations

Looks like Dell have finally sorted out the UPS shut down software for ESXi and vCenter.

Quick guide:
Download the software from the link below. Install the MUMC on the vCenter server if it's physical. Open the web console. Default username admin password admin
Under system and 'edit module settings' enable Virtualization.



After the new virtaulization submenu appears you can add the vCenter instance.


You should now see a new tab in vSphere client when you click on vCenter instance at the top of the tree.


Software download:
http://www.dell.com/support/drivers/us/en/19/driverdetails?driverid=NFF2Y

User guide:
http://www.dellups.com/pdf/Dell-TIN-UPS003_VMware_vCenter_Shutdown_Scenarios-10-11-12.pdf

YouTube guide:
http://www.youtube.com/watch?v=ZH5M-A465Eg

Old software :(
http://www.dell.com/support/drivers/us/en/555/DriverDetails/DriverFileFormats?c=us&l=en&s=biz&cs=555&DriverId=R318771

Tuesday, 24 January 2012

OpenManage Support for VMware ESXi 5.0

This page outlines OPENMANAGE SUPPORT FOR VMWARE ESXi 5.0 / vSphere v5.0

(Updated 12/12/2011)
Dell OpenManage Server Administrator agent officially supports vSphere v5.0 / ESXi 5 as of December 2011, starting with OMSA 6.5 A02.
Dell uses VMware's VIB mechanism to load the Dell OpenManage Server Administrator (OMSA) monitoring agent into ESXi. To complete the install, you will need to download the OpenManage 6.5 A02 OMSA vCenter Install Bundle (VIB). 
For instructions on how to install OpenManage Server Administrator 6.5 A02 on VMware ESXi, refer to theOpenManage 6.5 Server Administrator A02 ESXi 5.0 Tech Sheet.
For full documentation and support information about OpenManage and ESXi 5, visit the OpenManage 6.5 Server Administrator A02 Documentation page.

Monitoring Consoles
The OpenManage Essentials console allows you to monitor your ESXi5.0 systems in a one to many fashion. For more information about OME, visit www.delltechcenter.com/OME.
If you are interested in using the VMware vSphere console for managing your physical and virtual servers, consult the Dell TechCenter page outlining the Dell Management Plug-in for VMware vCenter.

Legacy Info:
Prior to December 2011, OMSA 6.5 A01 only partially supported ESX5i with caveats. Historical information is avalable in this document that outlined limited Dell OpenManage 6.5 A01 support of ESXi 5 . The content is provided “as is” and without express or implied warranties of any kind.

Tuesday, 17 January 2012

.NET bases applications are slow to load or certain in-app tasks are slow

This behaviour will occur with any .NET 1.1 and 2.0 assembly that is authenticode-signed, not only Measurement Studio assemblies. Digital signing is also referred to as code signing. Code signing a .NET library is strongly recommended by Microsoft, and Measurement Studio signs all of our ActiveX and .NET components.

Code signing of assemblies makes components tamper-proof and ensures that you know the identity of the component publisher.

The reason why this problem is occurring is because of the mechanism used by the .NET Common Language Runtime (CLR) to verify code-signed .NET assemblies. Part of the verification process requires an online look-up to check whether the certificate with which the assembly is signed has been revoked and is no longer valid. Windows does this by downloading a CRL (Certificate Revocation List). The first time a code-signed assembly is loaded by the .NET CLR, the CRL is downloaded from the certificate provider's server and cached on the system.

When the .NET CLR loads a code-signed assembly and is unable to reach the CRL distribution point, it records the failure as an inability to provide the assembly evidence that it was code-signed. So the assembly is allowed to load, but is not marked as being digitally signed. There is a 15 second delay for CRL retrievals. This is how long the CLR will keep on re-trying to download the CRL before it finally times out. So the delay in loading the .NET assembly occurs because Windows is unable to download the CRL and keeps trying to download it for 15 seconds before timing out.

This behavior is by design.

The .NET CLR will not indicate any error or throw any security exception when verifying a signed assembly if the CRL distribution point cannot be reached. An error here from 
WinVerifyTrust(), the API used by the .NET CLR to verify a code signed assembly, prevents the assembly from being marked as code signed. Note that this does not apply to assemblies loaded thru the Internet Explorer hosting interface.

You could manually download the CRL and install it on your system. But the CRL is valid only for 10-15 days, so unless your system is able to update the file after this time, you will run into the same problem again.

Microsoft recommends disabling CRL checking as a workaround by disabling this option in Internet Explorer. Use the following steps to disable the CRL checking in Internet Explorer:
  1. Select Start»Control Panel
  2. Double-click Internet Options
  3. Select the Advanced tab. 
  4. In the Security section, uncheck the Check for publisher's certificate revocation option.
By disabling the CRL checking using the Internet Options, you are not exposing yourself to a security threat because this check is not working. The reason why this problem is showing up is because your network settings are not allowing Windows to access the CRL.

In addition, it is possible to programmatically set the CRL verification. When the 
Check for publisher's certificate revocation is unchecked, a setting in the registry is changed. To turn off CRL verification, set HKCU\Software\Microsoft\Windows\CurrentVersion\WinTrust\Trust Providers\Software Publishing\State  from 0x00023c00 to 0x00023e00. To turn CRL Checking on again, reset the State key to 0x00023c00

Disabling IPv6 in Windows 2008

Unticking IPv6 in the NIC settings only disables IPV6 for that NIC. This does not apply to sudo NIC like Intra-Site Automatic Tunnel Addressing Protocol (ISATAP), 6to4 and Teredo. To disable this to the system open and CMD prompt with elevated privileges and execute this command:


reg add hklm\system\currentcontrolset\services\tcpip6\parameters /v DisabledComponents /t REG_DWORD /d 4294967295


Further reading: http://support.microsoft.com/kb/929852

Friday, 6 January 2012

Disabling network offloading in Windows

There is some useful info on offloading on this website www.windowsitpro.com/article/networking/give-microsofts-scalable-networking-pack-140350
But in my opinion it is still best to disable offloading. One example is the Microsoft Small Business Server best practices analyser recommends it, now why would Microsoft do this if it was not for the best.


To Determine the current state of offloading on the system issue these commands:


netsh int ip show global
netsh int tcp show global


To disable offloading issue these commands:

netsh int tcp set global rss=disabled
netsh int ip set global taskoffload=disabled
netsh int tcp set global autotuning=disabled
netsh int tcp set global congestion=none
netsh int tcp set global chimney=disabled

Remember this only disables offloading within the OS kernal, NOT the NICs! You can use the BACS control suite or the Intel driver options to disable this on the adapter.