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

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.

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.

SQL 2008 r2 Native client

http://go.microsoft.com/fwlink/?LinkID=188401&clcid=0x409

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

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.

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 ;)