ESXi not accepting previously used volume

I recently had a problem on an ESXi 5.0 box I was trying to add a iscsi target to. I had set up a 6 TB  iSCSI LUN but everytime I tried adding it to ESXI I got the following error:

Call "HostDatastoreSystem.QueryVmfsDatastoreCreateOptions" for object "ha-datastoresystem" on ESXi "ESX HOSTNAME" failed. 

It turned out that the setup wizard on the device had happily created a volume and formatted it with ext4 before I realised what it was doing. Although I removed this volume the partition information wasn't removed from the array and this was upsetting ESXi.

How do you fix it? As there was no obvious way to wipe the partition info from within the Array's management interface I decided to do it from a Debian VM running on that host.

Firstly I removed the discovery information from the ESXI server so it isn't trying to interfere then on the Debian VM I installed open-iscsi with:

apt-get install open-iscsi

Start the open-iscsi daemon with:

/etc/init.d/open-iscsi start

Query the iSCSI target on the storage device:

iscsiadm -m discovery -t st -p 192.168.1.99

Which should return something like this:
192.168.1.99:3260,0 iqn.2010-12.com.manufacturer:nasdevice.name

If you have set up iSCSI authentication on your storage device you will need to run something like the following commands using the iqn in the above response.

iscsiadm   --mode node  --targetname "iqn.2010-12.com.manufacturer:nasdevice.name"  -p 192.168.0.99:3260 --op=update --name node.session.auth.authmethod --value=CHAP
iscsiadm   --mode node  --targetname "iqn.2010-12.com.manufacturer:nasdevice.name"  -p 192.168.0.99:3260 --op=update --name node.session.auth.username --value=username
iscsiadm   --mode node  --targetname "iqn.2010-12.com.manufacturer:nasdevice.name"  -p 192.168.0.99:3260 --op=update --name node.session.auth.password --value=password

Logon to the storage device:

iscsiadm -m node --targetname "iqn.2010-12.com.manufacturer:nasdevice.name" --portal "192.168.0.99:3260" --login

All being well this should now create a SCSI device as if you had attached a hard drive directly to the system. I looked at the bottom of the output from the dmesg command to find out which device (/dev/sdb).

I used the following command to write zeros to the first half a MB of the disk which will overwrite any partition table information (care should be taken that you have the correct device when using this command, it will eat your drive):

 dd if=/dev/zero of=/dev/sdb bs=512 count=1024

Now logout of the storage device with the following command:

iscsiadm -m node --targetname "iqn.2010-12.com.manufacturer:nasdevice.name" --portal "192.168.0.99:3260" --logout

ESXi should now happily accept the iSCSI LUN when you attempt to add it.

Local security policy on Windows 8

The Local Security Policy MMC in Windows 8 how now been moved further away from the user (perhaps with good cause) and is available by searching for "secpol.msc."

This is reminiscent of the move to hide the Component services mmc in Windows 7/Windows Server 2008 R2 which can me accessed by searching for "comexp.msc."

Installation of .net 3.5 on Windows Server 2012

I struggled installing .net 3.5 on Windows 2012 Server. After going through the add features and selecting .net 3.5 I got the following Warning:

The request to add or remove feature on the specified server failed.
Installation of one or more roles, role services, or features failed. - The source files could not be downloaded.
Use the /source option to specify the location of the files that are required to restore the feature. The file location should be either the root directory of a mounted image or a component store that has the Windows Side-by-Side directory as an immediate subfolder.

From a administrative command prompt run the following:

dism.exe /online /enable-feature /featurename:NetFX3 /Source:d:\sources\sxs /LimitAccess /all

This will install .net 2.0 and 3.5.