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Virtualization, Cloud, Infrastructure and all that stuff in-between

My ramblings on the stuff that holds it all together

Category Archives: Reference

VMWare Server Performance – A Practical Example

 

The following screen dump is from an HP DL380G5 server that runs all the core infrastructure under VMWare Server (the free one) for a friend’s company which I admin sometimes.

It is housed in some co-lo space and runs the average range of Windows servers used by a small but global business, Exchange SQL, Windows 2003 Terminal Services.

As a result of some planned (but not very well communicated!) power maintenance the whole building lost power earlier today, when it was restored I grabbed the following screenshot as the 15 or so Virtual Machines automatically booted.

interesting to note that all the VM’s had been configured to auto-start with the guest OS, meaning there wasn’t any manual intervention required, even though it was a totally dirty shutdown for both the host and guest OS’es (No UPS, as the building and suite is supposed to have redundant power feeds to each rack – in this instance the planned maintenance was on the building wiring so required taking down all power feeds for a 5 yearly inspection..)

There are no startup delay settings  in the free version of VMWare Server so they all start at the same time, interesting to note the following points..

The blue line that makes a rapid drop is the pages/second counter, and the 2nd big drop (green) is the disk queue length. the hilighted (white) line is the overall %CPU time, note the sample frequency was 15 seconds on this perfmon.

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After it had settled down, I took the following screenshot, it hardly breaks a sweat during its working day. there are usually 10-15 concurrent users on this system from around the world (access provisioned via an SSL VPN device) and a pretty heavily used Exchange mail system.

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The box is an HP DL380 G5 with 2 x quad core CPUs (8 cores in total) and 16Gb of RAM, it has 8 x 146Gb 15k HDDs in a single RAID 5 set + hot-spare, it was purchased in early 2007 and cost c.£8,000 (UK Prices)

It runs Windows 2003 Enterprise Edition x64 edition with VMWare Server 1.0.2 (yes, its an old build.. but if it ain’t broke..) and they have purchased multiple w2k3 ent-edition licences to take advantage of the virtualisation use-rights to cover the installed virtual OS’es.

It’s been in-place for a year and hardly ever has to be touched, its rock-solidly available and the company have noticed several marked improvements since they P2V’d their old servers onto this platform, as follows;

  • No hardware failures – moving from lots of low-end servers (Dell) and desktops to a single box (10:1 consolidation)
  • The DL380 has good redundancy built in, but it’s also backed up with a h/w maintenence contract, and they also have a spare cold-standby server to resume service from backups if data is lost.
  • Less noise, the old servers were dotted around their old offices in corners, racks etc – this is the main thing they liked!
  • Simple access anywhere – using a Juniper SA2000 SSL VPN,  its easy to get secure access from anywhere
  • Less reliance on physical offices and cheap DSL-grade data communications, now the servers are hosted on the end of a reliable, data centre class network link with an SLA to back it up. if an individual office looses its ADSL connection, no real issue – people pick up their laptop(s) and work from home/starbucks etc.
  • Good comms are cheaper in data centres than in your branch offices (usually)

Hopefully this goes to show the free version of VMWare’s server products can work almost as well if budget is a big concern, ESX would definitely give some better features and make backup easier, they are considering upgrading and combining with something like Veeam Backup to handle failover/backup.

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HP Rapid Deployment Pack – PXE Settings for Deploying Windows OS

 

The followign screens show a working configuration from the RDP 3.80 PXE Configuration Manager

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Have had lots of problems with this deploying Windows OS’es and VMWare ESX 3.5 onto an HP c7000 Blade chassis, still not resolved all the problems, but this definitely works for deploying Windows!

The documentation reads like you should always use the Linux PE configuration and it handles switching between WinPE/LinuxPE depending on which OS job you drop on a target. in my experience this doesn’t work and you need to manually change the PXE configuration to default to LinuxPE or WinPE depending on the OS you want to target.

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And

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Still a work in progress as I have a c7000 to which I want to deploy a mix of Windows and ESX/Redhat OS’es….

I did get a previous installation to install ESX 3.5 by hacking the default ESX 3.02 job, but its since been re-installed and I can’t do it now

RDP 6.90 seems to list Windows 2008 and ESX 3.5 in the quickspecs, but I’ll be damned if I can find where to download it, going to have to call HP methinks!

As I’ve posted before installing via iLo is just a non-starter if you really do want a flexible and fast deployment configuration – so it has to be RDP.

More later…

How does an HP Fibre Channel Virtual Connect Module Work?

 

Techhead and I have spent a lot of time recently scratching our heads over how and where fibre channel SAN connections go in a c7000 blade chassis.

If you don’t know, a FC-VC module looks like this, and you install them in redundant pairs in adjacent interconnect bays at the rear of the chassis.

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You then patch each of the FC Ports into a FC switch.

The supported configuration is one FC-VC Module to 1 FC switch (below)

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Connecting one VC module to more than one FC switch is unsupported (below)

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So, in essence you treat each VC module as terminating all HBA Port 1’s and the other FC-VC module as terminating all HBA Port 2’s.

The setup we had:

  • A number of BL460c blades with dual-port Qlogic Mezzanine card HBAs.
  • HP c7000 Blade chassis with 2 x FC-VC modules plugged into interconnect bay 3 & 4 (shown below)

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The important point to note is that whilst you have 4 uplinks on each FC-VC module that does not mean you have 2 x 16Gb/s connection “pool or trunk” that you just connect into.

Put differently if you unplug one, the overall bandwidth does not drop to 12Gb/s etc. it will disconnect a single HBA port on a number of servers and force them to failover to the other path and FC-VC module.

It does not do any dynamic load balancing or anything like that – it is literally a physical port concentrator which is why it needs NPIV to pass through the WWN’s from the physical blade HBAs.

There is a concept of over-subscription, in the Virtual Connect GUI that’s managed by setting the number of uplink ports used.

Most people will probably choose 4 uplink ports per VC module, this is 4:1 oversubscription, meaning each FC-VC port (and there are 4 per module) has 4 individual HBA ports connected to it, if you reduce the numeber of uplinks you increase the oversubscription (2 uplinks = 8:1 oversubscription,  1 uplink = 16:1 oversubscription)

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Which FC-VC Port does my blade’s HBA map to?

The front bay you insert your blade into determines which individual 4Gb/s port it maps to and shares with other blades) on the FC-VC module, its not just a virtual “pool” of connections, this is important when you plan your deployment as it can affect the way failover works.

the following table is what we found from experimentation and a quick glance at the “HP Virtual Connect Cookbook” (more on this later)

FC-VC Port Maps to HBA in Blade Chassis Bay, and these ports are also shared by..
Bay3-Port 1, Bay-4-Port 1 1,5,11,15
Bay3-Port 2, Bay-4-Port 2 2,6,12,16
Bay3-Port 3, Bay-4-Port 3 3,7,9,13
Bay3-Port 4, Bay-4-Port 4 4,8,10,14

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Each individual blade has a dual port HBA, so for example the HBA within the blade in bay 12 maps out as follows

HBA Port 1 –> Interconnect Bay 3, Port 2

HBA Port 2 –> Interconnect Bay 4, Port 2

 

Looking at it from a point of a single SAN attached Blade – the following diagram is how it all should hook together

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 Path Failover

Unplugging an FC cable from bay 3, port 4 will disconnect one of the HBA imageconnections to all of the blades in bays 4,8,10 and 14 and force the blade’s host OS to handle a failover to its secondary path via the FC-VC module in bay 4.

 

A key take away from this is that your blade hosts still need to run some kind of multi-pathing software, like MPIO or EMC PowerPath to handle the failover between paths – the FC-VC modules don’t handle this for you.

 

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FC Loading/Distribution

A further point to take away from this is that if you plan to fill your blade chassis with SAN attached blades, each with an HBA connected to a pair of FC-VC modules then you need to plan your bay assignment carefully based on your server load.

Imagine if you were to put heavily used SAN-attached VMWare ESX Servers in bays 1,5,11 and 15 and lightly used servers in the rest of the bays then you will have a bottleneck as your ESX blades will all be contending with each other for a single pair of 4Gb/s ports  (one on each of the FC-VC modules) whereas if you distributed them into (for example) bays 1,2,3,4 then you’ll spread the load across individual 4Gb/s FC ports.

Your approach of course may vary depending on your requirements, but I hope this post has been of use.

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There is a very, very useful document from HP called the HP Virtual Connect Fibre Channel Cookbook that covers all this in great detail, it doesn’t seem to be available on the web and the manual and online documentation don’t seem to have any of this information, if you want a copy you’ll need to contact your HP representative and ask for it.

Exchange 2007 CCR Configuration Notes

 

Once you’ve followed the installation process and have your active and passive nodes setup you may not actually be able to failover and mount the stores – it fails and logs an event 9317 from MSExchangeSA as below;

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The fix is to register an SPN for each cluster node as per this KB article – why setup doesn’t do this for you I don’t know?

add-ADPermission -Identity “cn=exchange-cms,cn=computers,dc=mydomain,dc=com” -User “node-cl1$” -AccessRights WriteProperty -Properties “Validated-SPN”

You do this using the Exchange Management {Power}Shell Applet using the following command.

One thing to bear in mind – particularly if you are implementing a CCR cluster across mode than one physical site (single subnet required) you’ll need to wait for each node’s respective AD Domain Controller to replicate the changes.

Once that was completed I could fail over the cluster nodes perfectly.

Running Exchange 2007 on VMWare ESX Server

 

Interesting article here on some stress testing VMWare have done running Exchange 2007 under virtualization on VI3.5.

It’s working.. .and working well, now – official support?

Disaster Recovery Resource for Exchange

 

Stumbled across this site earlier; looks like there is some good practical information here if you are looking for how to handle Exchange backup and disaster recovery.

Sites like this are so much more valuable than the usual vendor white-paper approach as they show people’s real world experiences, mistakes, etc.

This is an employee from a commercial data recovery organisation, but this kind of resource is good for information sharing with the community…. and if it really goes wrong and you need to get into raw disk data recovery you have a level of confidence in their services and knowledge… an example of how blogs can deliver “business value”.