What is CTK file in Datastore (VM's folder)?

CTK file is created on VM's folder, when CBT is enabled on VMDK level (VM -> Edit Settings -> Options - General -> Confg paramaters) -> Refer below KB's for details.

Changed Block Tracking (CBT) is a VMware feature that helps perform incremental backups.
VMware Data Recovery uses this technology, and so can developers of backup and recovery software.

What is CBT and how it helps backup software?

If you look at the VM Aware backup software, Incremental Backups also  takes backup of Full VMDK size – If the file is modified after last Full Backup. In case of CBT is enabled assume few blocks are changed/added on VMDK -> CBT Helps to take only modified / added blocks not entire Giant VMDK. You may compare this to “Block level Incremental backups” (Not File Level incremental backups)

If CBT (Change Block Tracking) is enabled on a VM (we need to enable on each VMDK separately),
CBT feature will create additional files like vmname-cbt.vmdk, vmname-1-cbt.vmdk. (one CTK for one VMDK) in the same directory where it stores VMDK Descriptior & Flat Files

Once CBT is enabled on VMDK, since then ->
If any block changed on that VMDK - it will be recorded on associated .CTK map file of that VMDK. This map file (.CTK) helps VM Aware backup softwares to identify,
Since last Full backup, What are the blocks changed/added on that VMDK,
So Backup S/w does not need to backup whole VMDK - only backup the changed/added blocks.

By the way, What do mean by Block here and what would be the size of each Block??
Here the blocks are the small portions of VMDK (No relation with 1MB/8MB block size of VMFS)
CBT perspective, Block size (small portion of VMDK) - start from 64KB and varies if VMDK is big.

CBT is on a per VMDK level and not on a VMFS level.
CBT has variable block sizes which are dictated by the size of the VMDK.
CBT is a feature that lives within the VMKernel and not within VMFS.
CBT is a FS Filter as shown in the VMworld slide below

References
http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1020128

http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1031873

http://itknowledgeexchange.techtarget.com/virtualization-pro/what-is-changed-block-tracking-in-vsphere/

http://www.yellow-bricks.com/2009/12/21/changed-block-tracking/

Free VMware Learning Videos (By VMware)

www.vmwarelearning.com

Excellent opportunity to expand your VMware skills - Take advantage right away..
 

Grow your IT skills with free training, expertise, and insights on VMware products, all in one convenient location.

 

Instructional Videos – freely accessible, these short technical videos allow VMware technical experts to provide tips and step-by-step instructions on product features, design best practices, configuring, deploying and running your virtual infrastructure.

    Site Recovery Manager
    vCenter Operations
    vCenter Protect
    vCloud Director
    vFabric/Spring
    View
    vSphere
    vSphere Storage Appliance
    vCenter Orchestrator

UCS Manager Simulator Overview

Are you interested to work(simulate) on Cisco UCS Blades - and don’t want to invest heavy on Cisco UCS blade lab now (or) You don’t want to play with your Production Cisco UCS boxes - But to Practice / Train on UCS Blades - Here you go..


UCS - Simulator - Download URL
http://developer.cisco.com/web/unifiedcomputing/ucsemulatordownload

More on Setting Up appliance
http://www.petri.co.il/cisco-ucs-manager-simulator.htm



Cisco UCS Platform Emulator is the Cisco UCS Manager application bundled into a virtual machine (VM). The VM includes software that emulates hardware communications for the Cisco Unified Computing System. The UCS Platform Emulator (UCSPE) was developed to enable the use of Cisco UCS Manager and the UCS XML API without requiring physical hardware. UCSPE significantly shortens the development cycle for applications that are based on the UCS XML API. You can create and test programs using only UCSPE installed on a laptop.

UCSPE presents a controlled environment for the following:

• Emulation of large-scale environments
• Changes in the hardware inventory (device discovery)
• Firmware upgrade testing
• Troubleshooting real UCS problems

For example, you can use Cisco UCS Platform Emulator to create and test a supported Cisco UCS configuration, or to duplicate an existing Cisco UCS environment for troubleshooting or development purposes. Cisco UCS Platform Emulator supports both DHCP and static IP. By default, Cisco UCS Platform Emulator is configured to use the local network to obtain an IP address via DHCP. If your network does not include a DHCP server, you must assign a static IP address to Cisco UCS Platform Emulator.

vOptimizer Free | Storage Tool

vOptimizer Free examines VM storage allocations to detect VMs that are running out of disk space and identify VMs that are over-allocated in storage. vOptimizer Free also identifies misaligned virtal machines to improve performance.

Key Features:

    Detect VMs running out of storage
    Detect VMs with over-allocated storage
    Detect VMs with misaligned disk block partitions

More info at below URL
http://www.vkernel.com/products/voptimizer-free

vOPS™ Server Explorer

vOPS™ Server Explorer is -> Freeware suite comprised of multiple utilities that provide different angles of visibility into virtual environments.

1) Storage Explorer
Storage performance and capacity views across datastores and VMs that helps VM admins to get better visibility of their storage environment.

2) Change Explorer
Lists all changes that occurred to datacenters, clusters, resource pools, hosts, datastores and VMs within the previous seven days with associated risk impact

3) Environment Explorer
At-a-glance statistics of all hardware and virtual objects in an environment, VMs suffering from configuration and performance issues, details on efficiency problems, plus capacity for new VMs.

4) vScope Explorer
Designed to assess the health of a virtualized environment, this utility immediately identifies VMs, hosts and datastores that are suffering performance, capacity and efficiency issues.

5) SearchMyVM Explorer

Based on the award-winning SearchMyVM stand-alone free tool, this utility provides "Google-like" search capabilities into a virtual environment, and allows for export of the resulting reports.

http://www.vkernel.com/products/server-explorer/overview

Introducing VMware vCenter Support Assistant 5.1

VMware introduced "vCenter Support assistant"  - helps VMware Admins to log a case easily..
This will avoid the traditional way of logging ticket (below 3 steps - in 1 step now)
Ready made Plugin -  install on VC, will do all the jobs in "single window" for you..

1) Create VMware support bundle (log)
2) Create new SR with VMware
3) Upload Logs to VMware

VMware vCenter Support Assistant 5.1 is a free, downloadable plug-in for VMware vCenter Server. It provides an easy-to-use, secure, one-stop shop both for creating and managing support requests and generating and uploading logs. It is deployed as a virtual appliance and integrates with VMware vCenter Server as a plug-in that can be accessed using either the VMware vSphere Client or the VMware vSphere Web Client.

More about Plugin & Download Link
http://blogs.vmware.com/kb/2013/01/introducing-vmware-vcenter-support-assistant-5-1.html#.UQf7dvJ0g9I