What is IUSR and IWAM accounts

IUSR and IWAM date back to the very early days of IIS when we installed it separately (not as an OS component). By default, if a web site permits anonymous authentication, the IUSR account is used with respect to permissions on the OS. This can be changed from the default. There are some security recommendations to at least rename the account, so it’s not a “known” account, much like there is a recommendation to rename the administrator account on a server.

This accounts are created if we install IIS on local computer/ server.

If the IIS is installed on domain controllers then a domain account get created with IUSR_Servername & IWAM _servername as there is no local account for domain controllers.

If the server is no longer existing it should be safe to delete them.

If the server still exist with IIS installed, the account will be recreated automatically during the re/start of the IIS Admin

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Multi-path I/O (MPIO) does not work for disk with identifier … on node …

While configuring a Windows 2008 cluster, currently it has 3-nodes, getting ready to add 4th node. First step running it through cluster validation wizard.  The wizard keeps failing with the disk check returning following error:MPIO Error

My research indicated this might be iSCSI setting; because on Windows 2008 to use NAS technology in cluster environment iSCSI-Persist setting must be enabled.  Both [1] and [2] show how to enable that setting, but after our storage guys checked and made sure this setting was enabled we still could not get past this error. We verified flags on the HBA, the SANsurfer, and ECC Master Agent on the node with already configured nodes with no luck.

I had configured Windows 2008 Cluster (2-Node Cluster) before but never ran into this issue.  On this server we used PowerPath as agent to talk to EMC Symmetrix DMX-3.  I understanding is limited on NAS storage is limited so I didn’t know the functionality of PowerPath.  So the issue was not apparent, after looking at the 2-node cluster and the 3-node cluster we noticed the different agents were used to communicate between nodes and ECC storage.

The 3-Node cluster was configured to use SANsurfer, therefore to keep configuration on this cluster similiar we installed SANsurfer also.  However the issue remained; after reboot, we also noticed there are 59 disks visible on the server.  The server only has 2 physical disks and 29 masked; so it should be at most 30.  Looking at the cluster validation report I noticed that same disk was being masked to two ports; this is expected because of DUAL-HBA for failover.  This was same on all other nodes, so why did we not see duplicate disk on those nodes?

After digging through some documentation, talking to guys in office and internet digging, came up on [3].  Because Microsoft MPIO was not installed and not configured; each disk was mistakenly viewed as two disks.

MPIO vs Non-MPIO Diagram

Image from Microsoft TechNet [4]

So how to fix it now?  In Windows 2008, first you need to make sure Microsoft MPIO is installed, reference [5] on how to install it.  After you are finished installing bring up MPIO under Administrative tools.

MPIO Proprties Dialogbox

Should see something similar to the screen above, then click on “Discover Multi-Paths“.

MPIO Dialog box - Discover Multi-Paths Tab

In this screen if you notice on the bottom you will see EMC SYMMETRIX, select that and click Add.

Reboot Required - Confirmation Dialog Box

After which it will ask you to reboot, click “Yes”.  The problem should be resolved after reboot.

So I asked the storage expert on why did I need to configure this on this cluster and not the last one.  He said because PowerPath comes with Multi-Path I/O built in.  But because more and more people are using SAN/NAS technology with their servers Microsoft decided to add Multi-Path I/O into Windows 2008.  This makes it cheaper because then we don’t have to pay for extra license cost on PowerPath’s Multi-Path I/O.   However in his opinion, it is not as robust for load-balancing and but for failover technology (which is what I am using it for); it works without issues.

References

  1. TechNet. Windows Servers. Windows Server 2008 Cluster Disk cannot bring online. Link.
  2. Bryan Coffey’s Blog. Configuring Symmetrix DMX for Windows 2008 Cluster. Link.
  3. TechNet. Microsoft Multipath I/O Step-By-Step Guide. Link.
  4. TechNet. Microsoft Multipath I/O Step-By-Step Guide. Understanding MPIO features and components. Link.
  5. TechNet. Microsoft Multipath I/O Step-By-Step Guide. Installing and Configuring MPIO. Link.
  6. EMC2. EMC Symmetrix DMX-4 Series. Link.

Acknowledgment

I have faced this issue, but the solution i got it from below link, so all credit goes to below link.

Multi-path I/O (MPIO) does not work for disk with identifier … on node …

I have updated this in my blog for future reference & may be helofull for someone future

Can’t boot HP Envy laptop on windows 10 with USB flash drive to install dual boot.

To enable the USB flash drive boot on HP Envy laptop, you have to follow the below settings on Bios.

  1. Go to BIOS settings by pressing F-10. In system configuration you to disable “Secure boot” & then Enable “Legacy Support” as shown below.

2. After you restart your machine it will ask for code mentioned in the screen as shown below & then press enter to accept the BIOS changes.

2

Now even though you have enable the USB flash drive boot, boot the machine to install the dual boot, but while selecting the drive partition to install the operating system, you will receive error message about not being able to install on a GPT partition, it is because the computer was booted from a non-UEFI boot source or you selected to boot from a legacy boot source.

To fix the issue create a bootable USB flash drive with operating system ISO (Which needs to be dual boot).

I have used the free excellent tool called Rufus 2.3.709 to create the bootable flash drive.

  1. After clicking the rufus-2.3.exe, you have first select the ISO image by clicking the ISO/CD tab in below snap in.
  2. Then in Partitions scheme and target system type drop down there will be 3 option in which you have to select GPT partition scheme for UEFI.
  3. Then in file system you have to select FAT32 (Some computers may not recognize a valid UEFI enabled USB Flash drive if it is formatted as NTFS and may require a FAT32 formatted USB Flash drive.1
  4. Insert the USB flash drive, boot your laptop & select below highlighted USB drive with (UEFI) to start the operating system installation process.

2

Now you can select the drive where you can install the operating system without any error.

3

End of document!

 

What exactly is MSDTC, any when do I need it?

MSDTC (aka Microsoft Distributed Transaction Control) is a piece of software which a lot of people use, but they don’t really know what it does, or how it works.

MSDTC is used by SQL Server and other applications when they want to make a distributed transaction between more than one machine.  A distributed transaction is simple a transactions which spans between two or more machines.  The basic concept is that machine 1 starts a transaction, and does some work.  It then connects to machine 2 and does some work.  The work on machine 2 fails, and is cancled.  The work on machine 1 needs to then be rolled back.

DTC is for the most part a black box.  It just sort of works without much interaction exept for the initial setup.

The only time that DTC needs to be used is when more than one physical computer is going to be involved in an explicet distributed transaction.  If you are going from one instance to another on the same server DTC will not be needed.  If you are going from one instance to another within a cluster you will want to have DTC available as you may have to go between nodes of the cluster as you have no guarantee that the instances will be on the same physical node.

I hope this helps explain DTC a little bit at least.  If you have specific questions about DTC, feel free to post them below and I’ll try and find the answers for you.