Saturday, 13 March 2010

Notes on VMWare 4 (vSphere) and Server 2008 clustering

We're starting to put our key servers into clusters using server 2008 failover cluster manager.
Here are some key points we've learnt:

  • Create the first server in the cluster and install server 2008 (use R2 64 bit if you possibly can)
  • The server VM needs 2 network cards. Leave them both to use DHCP providing your DHCP and DNS is setup and working properly.
  • Your server's own C drive disk (which can be thin provisioned if you like) will be on the default SCSI controller (the default one will be set SCSI bus sharing: None)
  • Now add the shared hard disks. These must be on SCSI controller 1 or higher (not controller 0 - this is only for the windows drive). When you create the first one, the new SCSI controller will also appear. Configure this to SCSI bus sharing: Physical and controller type: Paravirtual
  • The first disk you create will be used by the clustering service (it's called a 'Witness' drive) to store info on the state of the cluster. This can be small (we set a VHD of 1GB, but it only uses about 100Mb).
  • Subsequent hard drives are the actual data drives. These can be raw mapped (RDM) if you don't want to use VHDs. When you raw map, VMWare creates a sparse VHD file which maps the physical disk to a virtual file, so it can work just like a 'normal' virtual disk - but you must set the compatibility mode to "Virtual" if you want to use snapshots. RDM physical mode is a direct link to the SAN so you can't use VMware's snapshot and backup facilities. Again, make sure they are all on the shared SCSI controlled (not controller 0).
  • If you're using an existing disk rather than creating a new one, it WON'T WORK if it's been converted to a dynamic disk. Convert it back to basic, or create a new basic disk and copy the files across. Sorry!
  • Create the rest of the servers and link them up to the disks you have created in the steps above (with the obvious exception of their C drives, which are private to each machine)
  • Now boot the first server, go to disk management, bring all the drives online and format them to NTFS. Go to server manager and add the file services role and the failover clustering feature.
  • Boot the rest of the cluster servers, go to disk management and bring all the drives online. They will already be formatted. Go to server manager and add the file services role and the failover clustering feature.
  • Back to the first server again. Go to failover cluster manager and add the new cluster. Verifying will probably fail, so don't expect MS support on your cluster (if you wanted it, you would probably need to cluster using MS virtualisation, not VMWare - good luck!)
  • In the new cluster, go to storage and add the disks
  • If the disk witness is not your small dedicated one, right click on the cluster name (top left), more actions and configure the quorum settings to use the correct disk
  • Now right click on service and applications and add a file server
  • Once that's done, right click on the shared folders and add the folders you want to share. If this fails, it's probably because the live copy of the disk is on another server in the cluster and it only allows you to add the folder from the same server that has the live disk. When created, you can right click on them and setup ABE and offline files options
  • Go to storage, right click on each disk and set up shadow copies (assuming you're going to use it) . You can also set up shares and security from here.
That's it. Your cluster share will appear under the name you set up for the file server application (not the same as any of the cluster servers). And it works!

Thursday, 11 March 2010

Server 2008 - Windows Update Woes

Automatic updates to one of our windows 2008 server virtual images are failing. MS has put out an update that will not apply - it tries every morning at 3am and fails.

Eventually it decided that it would reboot during the working day to apply the update, without giving us an option to abort. The update failed again.

We have now retired the S2008 image in favour of an S2008R2 64bit image which seems to take the updates OK. The affected servers were re-deployed with the new image.

We could have done without the extra work, though. Thanks MS (again).

Request for the permission of type 'System.Net.DnsPermission

IIS7 running a v2 asp.net app gave this error when trying to lookup from DNS despite full trust being in place and having worked fine for years, and nothing changing in the server config (I suppose there could have been a windows update - but I don't have the time to muck around chasing the garbage that sometimes gets churned out).

No amount of fiddling with trust would fix it.

Removing the web site from IIS manager and recreating it fixed it. Go figure! :-(

Thank you, Microsoft.