Archive

Archive for the ‘Free Tools’ Category

Verifying File Integrity using MD5 Checksum

May 22, 2011 1 comment

What is MD5 Checksum ?

According to Wikipedia ,  MD5 Message-Digest Algorithm is a widely used cryptographic hash function with a 128-bit (16-byte) hash value. Specified in RFC 1321, MD5 has been employed in a wide variety of security applications, and is also commonly used to check data integrity.An MD5 hash is typically expressed as a 32-digithexadecimal number. MD5 is more commonly used these days and is used to ensure the file integrity of files that we download.

How to verify MD5 for files that we download ?

Even though there are many tools to verify MD5 , I prefer the Microsoft FCIV (File Checksum Integrity Verifier) Utility which can be download from here.Fciv is a command line utility that computes and verifies hashes of files.It computes a MD5 or SHA1 cryptographic hash of the content of the file.

The FCIV utility has the following features:

  • Supports MD5 or SHA1 hash algorithms (The default is MD5.)
  • Can output hash values to the console or store the hash value and file name in an XML file
  • Can recursively generate hash values for all files in a directory and in all subdirectories (for example, fciv.exe c:\ -r)
  • Supplies an exception list to specify files or directories to hash
  • Can store hash values for a file with or without the full path of the file
Let’s try FCIV Utility to verify MD5 & SHA1 SUM for a vSphere Hypervisor Download.
Setting up FCIV Utility :
  1. Download FCIV Utility “Windows-KB841290-x86-ENU.exe
  2. Double click Windows-KB841290-x86-ENU.exe and extract it to a folder
  3. Add the FCIV folder to the system path or else every time you execute FCIV, one has to browse to the folder where  FCIV Utility has been  extracted .
  4. Go to command prompt and type fciv.exe /?, and then press ENTER to see the various options.
Ensuring File Integrity would mean that MD5 or SHA1 SUM value displayed on the website should match with that of the downloaded file.
In our case , VMware ESXi 4.1  download page tells me the MD5 and SHA1 SUM value for the ESXi 4.1 Update1 ISO image.
Once the download is complete , Open a command prompt and calculate the MD5 or SHA1 SUM as shown below using the FCIV utility .
fciv -add  -md5
fciv -add  -sha1
Categories: Free Tools, Servers Tags:

Web Server Load balancing with VMRUN Utility

September 26, 2010 3 comments

Recently , we had a requirement for automatic web server provisioning and load balancing in our environment . We use a Hardware Load balancer and the Web Servers are hosted on a VMware HA Cluster .  Optimizing the resource utilization is one of the main driving factors for this requirement since there are a lot of seasonal applications that would receive a huge load only during certain period of time like for example a payroll application which would see a huge load during the first five days of a month after which single server would be enough to take the load .

Automatic provisioning and load balancing would mean that we needed to have a tight integration between the load balancer and VMware . While we are working on achieving complete automation on provisioning and load balancing with the load balancer vendor , we set in place a temporary solution for the automatic load balancing using VMware VMRUN utility and VMware vCenter Alarm Actions.

What is VMRUN Utility ?

The vmrun utility runs on any VMware platform with VIX libraries installed, including VMware Workstation, VMware Fusion, ESX/ESXi Hosts,vCenter Server and VMware Server .We can use the vmrun command‐line utility to control specific virtual machines, or teams of virtual machines.We can use VMRUN to perform various tasks on virtual machines as specified below :

  • Power commands
  • Snapshot Commands
  • Record and Replay Commands
  • Guest OS Commands
  • Maintenance Commands
  • VProbes Commands

As a temporary workaround we installed and configured the web application on 5 different VMs and added them as part of the Web Server Pool in the hardware load balancer and ensured every one of them is working fine . We then powered off  VM2,VM3,VM4 & VM5 as VM1 would be able to take the non-peak load . Download and install VMware VIX components in the Virtual Center Server . Now we set out to set vCenter alarm action for VM1 to power on VM2 whenever the CPU utilization exceeded 75% for a continuous period of 5 minutes and similarly for VM2 to power on VM3 , VM3 to power on VM4 and VM4 to power on VM5. On the vCenter alarm action for the VM CPU Utilization , set the alarm action as Run a command and run a simple batch file to invoke VMRUN to power on VM desired ( in this case power on VM2 )  since there is no direct way of powering on VM2 on the vCenter alarm action . Similarly set alaram actions for rest of the Virtual Machines on the web server pool . Shutting down of the Virtual Machines would happen the same way just that we start from shutting down VM5 and come down till VM2 . Again we considered CPU utilization as a criteria for shutting down the Virtual machines.:

Syntax to list registered VMs using VMRUN Utility :

C:\Program Files (x86)\VMware\VMware VIX>vmrun.exe -T esx -h https://IP Address of  VC/sdk -u USERNAME -p PASSWORD listRegisteredVM

Syntax to Power on VM using VMRUN Utility:

vmrun.exe -T esx -h https://IP Address of VC/sdk -u USERNAME -p PASSWORD start “VMX Path of the Virtual Machine”

While we are working on a solution to  automate the entire process , vCenter Alarm actions and VMRUN utility helped us with a temporary workaround . Power of VMware !!

RV Tools Updated

September 15, 2010 1 comment

Rob de Veij has done it again . RV Tool , the Number 1 free tool for ESX , has been updated again with some cool features and a new version 2.9.5 can be downloaded from here.

Some of the additional features that has been added in the latest release are :

  • On vInfo tab new field: Guest heartbeat status. The heartbeat status is classified as:  gray – VMware Tools are not installed or not running, red – no heartbeat, guest operating system may have stopped responding. yellow – intermittent heartbeat, may be due to guest load. green – guest operating system is responding normally
  • On vMemory tab new fields: Ballooned memory, consumed overhead memory, private memory, shared memory, swapped memory and static memory entitlement


  • On vDatastore tab new field: Full device address (controller, target, device)
  • On vInfo tab new fields: committed storage, uncommitted storage and unshared storage

And some bug fixes ,
  • A semicolon in the annotations fields are no longer a problem for the export functions
  • Health check “Zombie vmdk” problems solved
  • Health check “inconsistent foldername” problems solved
  • On vport tab the column “notify switch” value solved
  • Sort problem on vNic tab on column “speed” solved

In case you didn’t know about RV Tool , I have discussed on my previous post here.

RV Tools

August 30, 2010 1 comment

One of the first tools that I used as a VMware Administrator was RV Tools by Rob de Veij and the tool has gone through many upgrades . RV Tools is a windows .NET 2.0 application which uses the VI SDK to display information about virtual machines and ESX hosts. This displays a lot of information about the Virtual infrastructure in a single console which otherwise is not possible using in-built management tools .

This tool displays information about the following parameters

  • vInfo
  • vCPU
  • vMemory
  • vDisks
  • Nics
  • CD-Rom
  • Floppy drives
  • Snapshots
  • VMware tools
  • ESX hosts
  • Datastores
  • Switches
  • Ports
  • Health checks

You can connect either directly to ESX Server or Virtual Center to view information about multiple hosts.
All data that you can see on the application can also be exported to CSV format.
User with minimal access such as read access to the Virtual Center will also be able to fetch all the information and that’s cool .
Floppy Drives and CD drives can be disconnected using the application itself.
VMware tools can also be upgraded from the application itself .


Health Check Tab displays useful alerts like Snapshot information , drives running out of free space , Inconsistent folder names etc.. and thresholds are configurable

You can dowload the tool from Rob de Veij’s website http://www.robware.net/ and a big THANK YOU to him !!

Categories: Free Tools, VMware Tags: , ,