VMware difference between

1. What is the difference between the vSphere ESX and ESXi architectures?

VMware ESX and ESXi are both bare metal hypervisor architectures that install directly on the server hardware.

Although neither hypervisor architectures relies on an OS for resource management, the vSphere ESX architecture relied on a Linux operating system, called the Console OS (COS) or service console, to perform two management functions: executing scripts and installing third-party agents for hardware monitoring, backup or systems management.

In the vSphere ESXi architecture, the service console has been removed. The smaller code base of vSphere ESXi represents a smaller “attack surface” and less code to patch, improving reliability and security.

find the below screenshot for more details - 

2. What is the difference between clone and template in VMware?

Clone

• A clone is a copy of virtual machine.
• You cannot convert back the cloned Virtual Machine.
• A Clone of a Virtual Machine can be created when the Virtual Machine is powered on
• Cloning can be done in two ways namely Full Clone and Linked Clone.
• A full clone is an independent copy of a virtual machine that shares nothing with the parent virtual machine after the cloning operation. Ongoing operation of a full clone is entirely separate from the parent virtual machine.
• A linked clone is a copy of a virtual machine that shares virtual disks with the parent virtual machine in an ongoing manner. This conserves disk space, and allows multiple virtual machines to use the same software installation.
• Cloning a virtual machine can save time if you are deploying many similar virtual machines. You can create, configure, and install software on a single virtual machine, and then clone it multiple times, rather than creating and configuring each virtual machine individually.

Template

• A template is a master copy or a baseline image of a virtual machine that can be used to create many clones.
• Templates cannot be powered on or edited, and are more difficult to alter than ordinary virtual machine.
• You can convert the template back to Virtual Machine to update the base template with the latest released patches and updates and to install or upgrade any software and again convert back to template to be used for future deployment of Virtual Machines with the latest patches.
• Convert virtual Machine to template cannot be performed, when Virtual machine is powered on.  Only Clone to Template can be performed when the Virtual Machine is powered on.
• A template offers a more secure way of preserving a virtual machine configuration that you want to deploy many times.
• When you clone a virtual machine or deploy a virtual machine from a template, the resulting cloned virtual machine is independent of the original virtual machine or template

3. What is the difference between Thick provision Lazy Zeroed, Thick provision Eager Zeroed and Thin provision?

Thick Provision Lazy Zeroed

• Creates a virtual disk in a default thick format.
• Space required for the virtual disk is allocated when the virtual disk is created.
• Data remaining on the physical device is not erased during creation, but is zeroed out on demand at a later time on first write from the virtual machine.
• Using the default flat virtual disk format does not zero out or eliminate the possibility of recovering deleted files or restoring old data that might be present on this allocated space.
• You cannot convert a flat disk to a thin disk.

Thick Provision Eager Zeroed

• A type of thick virtual disk that supports clustering features such as Fault Tolerance.
• Space required for the virtual disk is allocated at creation time.
• In contrast to the flat format, the data remaining on the physical device is zeroed out when the virtual disk is created.
• It might take much longer to create disks in this format than to create other types of disks.

Thin Provision

• It provides on on-demand allocation of blocks of data.
• All the space allocated at the time of creation of virtual disk is not utilized on the hard disk, rather only the size with utilized data is locked and the size increases as the amount of data is increased on the disk.
• With thin provisioning, storage capacity utilization efficiency can be automatically driven up towards 100% with very little administrative overhead.

4.Comparison and Difference between VMFS 3 and VMFS 5

New Unified 1MB File Block Size

Earlier versions of VMFS used 1, 2, 4 or 8MB file blocks. These larger blocks were needed to create large files (>256GB). These different file blocks sizes are no longer needed to create large files on VMFS-5. Very large files can now be created on VMFS-5 using the new unified 1MB file blocks. Earlier versions of VMFS will still have to use larger file blocks to create large files.

Large Single Extent Volumes

In earlier versions of VMFS, the largest single extent was 2TB - 512 bytes. An extent is a partition on which one can place a VMFS. To create a 64TB VMFS-5, one needed to create 32 x 2TB extents/partitions and join them together. With VMFS-5, this limit for a single extent/partition has been increased to 64TB.

Smaller Sub-Blocks

VMFS-5 introduces smaller sub-blocks. Sub-blocks are now 8KB rather than 64KB as used in the earlier versions. With VMFS-5, small files (< 8KB, but > 1KB) in size will consume only 8KB rather than 64KB. This will reduce the amount of disk space stranded by small files. Also, there are many more sub-blocks in VMFS-5 than there were in VMFS-3 (32,000 on VMFS-5 compared to approximately 4,000 on VMFS-3).

Small File Support

VMFS-5 introduces support for very small files. For files less than or equal to 1KB, VMFS-5 uses the file descriptor location in the metadata for storage rather than file blocks. When these files grow beyond 1KB, they will then start to use the new 8KB sub-blocks.

Increased File Count

VMFS-5 introduces support for greater than 120,000 files, a four-fold increase when compared to the number of files supported on VMFS-3, which was approximately 30,000.

GPT

VMFS-5 now uses GPT partition table rather that MBR table as used by earlier version of VMFS extending the maximum partition size to 64TB which was limited to 2TB in earlier verions of VMFS.

Limitation of upgrading filesystem from VMFS-3 to VMFS-5

While a VMFS-3 which is upgraded to VMFS-5 provides you with most of the capabilities as a newly created VMFS-5, there are some differences.

No Uniform Block Size

VMFS-5 upgraded from VMFS-3 continues to use the previous file-block size, which may be larger than the unified 1MB file-block size.

No New Sub-Block Size

VMFS-5 upgraded from VMFS-3 continues to use 64KB sub-blocks and not the new 8KB sub-blocks. This can also lead to stranded/unused disk space. The upgraded VMFS-5 also continues to use the original number of sub-blocks from the VMFS-3.

No Increase to the Maximum Number of Files per Datastore

VMFS-5 upgraded from VMFS-3 continues to have a file limit of 30,720 rather than new file limit of > 100,000 for newly created VMFS-5.

Uses MBR

VMFS-5 upgraded from VMFS-3 continues to use MBR (Master Boot Record) partition type; when the VMFS-5 volume has grown beyond 2TB, it automatically and seamlessly switches from MBR to GPT (GUID Partition Table) with no impact on the running virtual machines.

Starts on Sector 128

VMFS-5 upgraded from VMFS-3 continues to have its partition starting on sector 128. Newly created VMFS-5 partitions will have their partition starting at sector 2048.

5.Difference between VMware ESX and ESXi

What is VMware ESX ?

ESX (Elastic Sky X) is the VMware’s enterprise server virtualization platform. In ESX, VMkernel is the virtualization kernel which is managed by a console operating system which is also called as Service console. Which is linux based and its main purpose is it to provide a Management interface for the host and lot of management agents and other thrid party software agents are installed on the service console to provide  the functionalists like hardware management and monitoring of ESX hypervisor.                                                                                                                                         

Graphic Thanks to VMware

What is VMware ESXi ?

ESXi (Elastic sky X Integrated) is also the VMware’s enterprise server virtualization platform. In ESXi, Service console is removed. All the VMware related agents and third party agents such as management and monitoring agents can also run directly on the VMkernel. ESXi is ultra-thin architecture which is highly reliable and its small code-base allows it to be more secure with less codes to patch. ESXi uses Direct Console User Interface (DCUI) instead of a service console to perform management of ESXi server. ESXi installation will happen very quickly as compared to ESX installation.

Graphic Thanks to VMware

Difference between ESX and ESXi

 ESX 4.1 is the last version availability of ESX server. After vSphere 5, only ESXi is available.  This comparison based out of the VMware Article

Capability	ESX	ESXi
Service Console	Present	Removed
Troubleshooting performed via	Service Console	ESXi Shell
Active Director Authentication	Enabled	Enabled
Secure Syslog	Not Supported	Supported
Management Network	Service Console Interface	VMKernel Interface
Jumbo Frames	Supported	Supported
Hardware Montioring	3 rd Party agents installed in Service console	Via CIM Providers
Boot from SAN	Supported in ESX	Supported in ESXi
Software patches and updates	Needed as smilar to linux operation system	Few pacthes because of small footprint and more secure
vSphere web Access	Only experimental	Full managenet capability via vSPhere web client
Locked Down Mode	Not present	Present . Lockdown mode prevents remote users to login to the host
Scripted Installtion	Supported	Supported
vMA Support	Yes	Yes
Major Administration command-line Command	esxcfg-	esxcli
Rapid deployment via Auto Deploy	Not supported	Supported
Custom Image creation	Not supported	Supported
VMkernel Network Used for	vMotion,Fault Tolarance,Stoarge Connectivity	Management Network , vMotion, Fault Tolarance, Stoarge Connectivity, ISCSI port binding

 6.Difference between ESX 3.5 and ESX 4.0

Here is the Post with the Difference between ESX 3.5 & ESX 4. I believe this would be the one of the definite questions in interview. Will working towards to bring the differences between all editions of ESX version.

–>

Features	ESX 3.5	ESX 4
Linked Mode	No Linked Mode Support	Linked Mode Supportis introduced in vSphere 4.0
Host Profiles	No Host Profiles	Host Profiles is Introduced in vSphere 4.0
Centralized License	Require dedicated License server	License can be managed within vCenter server
Performance chart	Yes	Lot More enhancements
Events and Alarms	Yes	Lot More enhancements
Fault tolerance	Not Available	Available from vSphere 4.0
Storage VMotion	SVMotion available only with CLI	SVMotion available in GUI
VMotion	Yes	Yes
Virtual CPUs per host	192	512
Virtual Machines per host	170	320
Logical processors per host	32	64
RAM per host	256 GB	1 TB
Maximum Service console Memory	800 MB	800 MB
DRS	Yes	Yes
VMware Data Recovery	Backup using VCB (VMware Consolidated backup)	VMware Data Recovery and VCB support
Enhanced VMotion Compatibility  (EVC)	No EVC	EVC is introduced in vSphere 4.0
VMware HA Admission Control	Yes but without options to reserve  failover capacity	Admission Control is improved to provide more flexible configuration options to reserve failover capacity.
High Availability Clustering with Windows Server 2000, 2003, 2008	Not Available	Available  in vSphere 4.0
Serial Attached SCSI (SAS)	Not Available	Available to support MSCS on win 2008
Hosts per storage volume	32	64
Fiber Channel paths to LUN	32	16
NFS Datastores	32	64
Hardware iSCSI initiators per host	2	4
Virtual Machine Hot Add Support	NO	Yes
Number of virtual CPUs per  virtual machine	4	8
Virtual Hardware version	4	7
RAM per virtual machine	64 GB	255 GB
virtual machine swap file Size	65532MB	255GB
VMDirectPath for Virtual Machines	NO	Yes
Vmkernel	32 Bit	64 bit
Service Console	32 Bit	64 bit
Concurrent remote console sessions	10	40
Virtual Disk Thin Provisioning	No Thin Provisioning	Thin Provisioning introduced in vSphere 4.0
VMware Paravirtualized SCSI (PVSCSI	Not available	High-performance storage adapters that offer greater throughput and lower CPU utilization for virtual machines
Hot Extend for Virtual Disks	Only Via VCLI using vmkfstools	Available via GUI
Hot plug support for virtual devices	No	Yes
VMXNET Generation 3	Not Available	Yes
vNetwork Distributed Switch	Not Available	Available from vSphere with Enterprise Plus License
Private VLAN Support	Not Available	Available  with DVSwitch
Network Vmotion	Not Available	Available with DVSwitch
3rd Party Distributed Switch Support	Not Available	We can use Cisco Nexus 1000v with DVSwitch
IPv6 Support	Yes	Yes
NICs per VM	4	10
Standard vSwitches per host	127	248
Virtual NICs per standard vSwitch	1016	4088
8 way SMP	No Only 4 way	Yes
Update Manager	Yes	Yes
DPM	Experimental	Fully supported with PMI and iLO Remote Power On
License Types	VMware Infrastructure Foundation VMware Infrastructure Standard VMware Infrastructure Enterprise	vSphere  Essentials vSphere Essentials Plus vSphere  Standard vSphere Advanced vSphere Enterprise vSphere Enterprise Plus

 

7.Difference between vSphere 4.1 and vSphere 5

I am getting lot of request from email to post the difference between the vSphere 4.0 and vSphere 5.0. Here the post for the requests and I believe this could be the definite questions in interviews and this post helps you to just quickly review the difference between the features of this 2 vSphere Releases.

Features	vSphere 4.1	vSphere 5.0
Hypervisor	ESX & ESXi	Only ESXi
VMA	Yes VMA 4.1	Yes VMA 5
HA Agent	AAM Automatic Availability Manager	FDM Fault Domain Manager
HA Host Approach	Primary & Secondary	Master & Slave
HA Failure Detection	Management N/W	Management N/W and Storage communication
HA Log File	/etc/opt/vmware/AAM	/etc/opt/vmware/FDM
DNS Dependent on DNS	Yes	NO
Host UEFI boot support	NO	boot systems from hard drives, CD/DVD drives, or USB media
Storage DRS	Not Available	Yes
VM Affinity & Anti-Affinity	Available	Available
VMDK  Affinity & Anti-Affinity	Not Available	Available
Profile driven storage	Not Available	Available
VMFS version	VMFS-3	VMFS-5
VSphere Storage Appliance	Not Available	Available
Iscsi  Port Binding	Can be only done via Cli using ESXCLI	Configure dependent hardware iSCSI and software iSCSI adapters along with the network configurations and port binding in a single dialog  box using the vSphere Client.
Storage I/O control for NFS	Fiber Channel	Fiber Channel & NFS
Storage Vmotion Snapshot support	VM with Snapshot cannot be migrated using Storage vMotion	VM with Snapshot can be migrated using Storage vMotion
Swap to SSD	NO	Yes
Network I/O control	Yes	Yes with enhancement
ESXi firewall	Not Available	Yes
vCenter Linux Support	Not Available	vCenter Virtual Appliance
vSphere Full Client	Yes	Yes
vSphere Web Client	Yes	yes with lot of improvements
VM Hardware Version	7	8
Virtual CPU per VM	8 vCpu	32 vCpu
Virtual Machine RAM	255 GB	1 TB of vRAM
VM Swapfile size	255 GB	1 TB
Support for Client connected USB	Not Available	Yes
Non Hardware Accelerated 3D grpahics support	Not Available	Yes
UEFI Virtual BIOS	Not Available	Yes
VMware Tools Version	4.1	5
Mutlicore vCpu	Not Available	Yes  configure at VM setting
MAC OS Guest Support	Not Available	Apple Mac OS X Server 10.6
Smart card reader support for VM	Not Available	Yes
Auto Deploy	Not Available	Yes
Image Builder	Not Available	Yes
VM’s per host	320	512
Max Logical Cpu per Host	160	160
RAM per Host	1 TB	2 TB
MAX RAM for Service Console	800 MB	Not Applicable (NO SC)
LUNS per Server	256	256
Metro Vmotion	Round-trip latencies of up to 5 milliseconds.	Round-trip latencies of up to 10 milliseconds. This provides better performance over long latency networks
Storage Vmotion	Moving VM Files using moving to using dirty block tracking	Moving VM Files using I/O mirroring with better enhancements
Virtual Distributed Switch	Yes	Yes with more enhancements like deeper view into virtual machine traffic through Netflow and enhances monitoring and troubleshooting capabilities through SPAN and LLDP
USB 3.0 Support	NO	Yes
Host Per vCenter	1000	1000
Powered on virtual machines  per vCenter Server	10000	10000
Vmkernel	64-bit	64-bit
Service Console	64-bit	Not Applicable (NO SC)
Licensing	vSphere Essentials vSphere Essentials Plus vSphere Standard vSphere Advanced vSphere Enterprise vSphere Enterprise Plus	vSphere Essentials vSphere Essentials Plus vSphere Standard vSphere Enterprise vSphere Enterprise Plus

8. Difference Between VMFS 3 and VMFS 5

This post explains you the major difference between VMFS 3 and VMFS 5. VMFS 5 is available as part of vSphere 5. VMFS 5 is introduced with lot of performance enhancements. Newly installed ESXi 5 will be formatted with VMFS 5 version but if you have upgraded the ESX 4 or ESX 4.1 to ESXi 5, then datastore version will be VMFS 3 only. You will able to upgrade the VMFS 3 to VMFS 5 via vSphere client once ESXi upgrade is Complete. This posts tells you some major differences between VMFS 3 and VMFS 5  

Capability	VMFS 3	VMFS 5
Maximum single Extend size	2 TB  less 512 bytes	64 TB
Partition Style	MBR (Master Boot Record) style	GPT (GUID Partition Table)
Available Block Size	1 MB/2MB/4MB/8MB	only 1 MB
Maximum size of RDM in Virtual Compatibiltiy	2 TB  less 512 bytes	2 TB  less 512 bytes
Maximum size of RDM in Phsical Compatibiltiy	2 TB  less 512 bytes	64 TB
Supported Hosts versions	ESX/ESX 3.X, 4.X & 5.x	Only ESXi 5 is supported
Spanned Volume size	64 TB (32 extends with max size of extent is 2 TB)	64 TB (32 extends with any size combination)
Upgrade path	VMFS 3 to VMFS 5	Latest Version. NO upgarde  available yet.
File Limit	30,000	100,000
Sub-Block size	64 KB	8 KB

9.Difference between Upgraded VMFS 5 and Newly created VMFS5

This post explains you the major difference between VMFS 5 datastore upgrade from VMFS 3 and  newly created VMFS 5 datastore. VMFS 5 is available as part of vSphere 5. VMFS 5 is introduced with lot of performance enhancements. Newly installed ESXi 5 will be formatted with VMFS 5 version but if you have upgraded the ESX 4 or ESX 4.1 to ESXi 5, then datastore version will be VMFS 3 only. You will able to upgrade the VMFS 3 to VMFS 5 via vSphere client once ESXi upgrade is Complete. Even though the upgraded datastore will be with VMFS 5 version  but there are many technical difference between upgraded VMFS 5 and newly created VMFS 5. This posts tells you some major differences between upgraded VMFS 5 and  newly created VMFS 5.

 

Capabilities	Upgraded VMFS 5	Newly Created VMFS 5
Max datastore size	64 TB	64 TB
Maximum size of RDM in Physical Compatibility	64 TB	64 TB
Block Size	Continuous to use the previous block size which may be 1MB/2MB/4MB/8 MB	only 1 MB block size
Sub-block size	64 KB sub-blocks	8 KB  sub-blocks
File limit	30,000	100,000
Partition Style	MBR (Master Boot Record) style	GPT (GUID Partition Table)
Partition Sector	partition starting on sector 128	partition starting on sector 2,048
Maximum size of RDM in Virtual Compatibility	2 TB  less 512 bytes	2 TB  less 512 bytes
Max size of file	2 TB  less 512 bytes	2 TB  less 512 bytes

10. Difference between vpxa, vpxd and hostd.

hostd is an app that runs in the Service Console that is responsible for managing most of the operations on the ESX machine.  It knows about all the VMs that are registered on that host, the luns/vmfs volumes visible by the host, what the VMs are doing, etc.  Most all commands or operations come down from VC through it.  i.e, powering on a VM, VM vMotion, VM creation, etc.
vpxa also runs on the Service Console and talks to VC.  I believe it acts as an intermediary between VC and hostd. I think it also does some housekeeping on the ESX host, but not as much as hostd.

Vmware hostd and vpxa on ESXi 5.X

 

HOSTD

The vmware-hostd management service is the main communication channel between ESX/ESXi hosts and VMkernel. If vmware-hostd fails, ESX/ESXi hosts disconnects from vCenter Server/VirtualCenter and cannot be managed, even if you try to connect to the ESX/ESXi host directly. It knows about all the VMs that are registered on that host, the luns/vmfs volumes visible by the host, what the VMs are doing, etc. Most all commands or operations come down from VC through it. i.e, powering on a VM, VM vMotion, VM creation, etc.

Restart the management agent /etc/init.d/hostd restart
VPXA

It acts as an intermediary between VC and hostd. The vCenter Server Agent, also referred to as vpxa or the vmware-vpxa service, is what allows a vCenter Server to connect to a ESX host. Specifically, vpxa is the communication conduit to the hostd, which in turn communicates to the ESX kernel. Restart the vpxa service
/etc/init.d/vpxa restart

Note:- If you have SSH enabled on your ESXi server these services can also be restarted and even if these are restarted by you then also your SSH session will not be impacted.

VPXD-It is Vcenter Server Service. If this service is stopped then we will not able to connect to Vcenter Server via Vsphere client.
VPXA-It is the agent of Vcenter server. also known as mini vcenter server which is installed on the each esx server which is managed by Vcenter server. What are the management action we are performing on top of the vcenter server. (Like:- Increasing/Decreasing RAM & HDD, Making any type of changes in cluster, doing vmotion. This agent collects all information from the vcenter server and pass this information to the kernal of the esx server.
HOSTD- This is the agent of ESX server, here VPXA pass the information to the HOSTD and hostd pass the information to ESX server.
In ESX, you have only hostd and (if you have vCenter) vpxa.
These are daemon (services) for remote management:

• hostd is used to remote management using VIC
• vpxa is used by vCenter (the vpxd part of vCenter) to remote manament

hostd is the daemon for direct VIC connection (when you use Virtual Infra Client (VIC) to connect to your ESX).
Also,

• vpxa is the VC agent (ESX side)
• vpxd is the VC daemon (VC side)

explained in different way -

what is VPXD, VPXA and HOSTD ?

VPXD-It is Vcenter Server Service. If this service is stopped then we will not able to connect to Vcenter Server via Vsphere client.

VPXA-It is the agent of Vcenter server. also known as mini vcenter server which is installed on the each esx server which is managed by Vcenter server. What are the management action we are performing on top of the vcenter server. (Like:- Increasing/Decreasing RAM & HDD, Making any type of changes in cluster,
doing vmotion. This agent collects all information from the vcenter server and pass this information to the kernal of the esx server.

HOSTD- This is the agent of ESX server, here VPXA pass the information to the HOSTD and hostd pass the information to ESX server.

 

Difference between Standard Switch and Distributed switch

In this post, I have explained the major differences about standard and distributed switch.
                             VS

Features	Standard Switch	Distributed Switch
Management	Standard switch needs to managed at each individual host level	Provides centralized management and  monitoring of the network configuration  of all the ESXi hosts that are associated with the dvswitch.
Licensing	Standard Switch is available for all  Licensing Edition	Distributed switch is only available for enterprise edition of licensing
Creation & configuration	Standard switch can be created and  configured at ESX/ESXi host level	Distributed switch can be created and configured  at the vCenter server level
Layer 2 Switch	Yes, can forward Layer 2 frames	Yes, can forward Layer 2 frames
VLAN segmentation	Yes	Yes
802.1Q tagging	Can use and understand 802.1q VLAN tagging	Can use and understand 802.1q VLAN tagging
NIC teaming	Yes, can utilize multiple uplink to  form NIC teaming	Yes, can utilize multiple uplink to form  NIC teaming
Outbound Traffic Shaping	Can be achieved using standard switch	Can be achieved using distributed switch
Inbound Traffic Shaping	Not available as part of standard switches	Only possible at distributed switch
VM port blocking	Not available as part of standard  switches	Only possible at distributed switch
Private VLAN	Not available	PVLAN can be created as part of dvswitch. 3 types of PVLAN(Promiscuous,  Community and Isolated)
Load based Teaming	Not available	Can be achieved using distributed switch
Network vMotion	Not available	Can be achieved using distributed switch
Per Port policy setting	Policy can be applied at switch and port group	Policy can be applied at switch, port group and even per port level
NetFlow	Not available	Yes
Port Mirroring	Not available	Yes