SATA vs IDE? What’s the difference and what’s better? This page will explain the differences and the pros and cons of each cable. SATA or IDE? Find out.


IDE: (Integrated Drive Electronics)


The SATA cable or Serial ATA cables are only 7 pins wide compared to the IDE Ribbon Cable which is 40 pins. The SATA cables are also longer then the ribbon cables (some up to 1m) which make them more useful in large cases. The PATA or IDE cables are only 45cm long and can connect two hard drives to the motherboard while the SATA cable connects only one hard drive to the motherboard.


The next step in IDE vs SATA is to work out the data transfer speeds. IDE (PATA) transfers data from the speeds of 5MB/sec up to 133MB/Sec (ATA100/133). SATA however data transfer speeds range from 150MB/sec to SATA II which doubles it to 300MB/sec.


IDE vs SATA in the aspect of jumpers again goes the way of SATA. With the IDE cable you need to always mess around with the jumpers since their may be two hard drives or two CD drives or one of each on the one cable. With SATA there is only the one cable so there are no jumpers to mess around with. If you are new to computers then a SATA hard drive will be easier to install.


In summary of SATA vs IDE, the SATA cable is smaller, faster and therefore better. It can reach further then a IDE cable and will also reduce the obstruction to air cooling which IDE cables can contribute to. The cables also transfer data much faster (more crucial if you have two or more hard drives) and are easier to install since their are no jumpers. The only downfall of the SATA is that they easily fall out of their positions and that you can only have one drive per cable.

VMware vSphere 4.x Install Configure Manage FAQ

Q1) Are we able to add odd number virtual CPUs to our virtual machines, for example 3 or 5 VCPU as compared to VI3 version when virtual SMP only supports 2 or 4 VCPU per virtual machine ?

Yes, we can now add odd number VCPU to our virtual machines.


Q2) What is the limitation for configuring VMware Fault Tolerance for a virtual machine ?

Virtual machine selected for VMware FT must be provisioned with thick disk and not thin disk, if it was provisioned with thin disk, there will be a prompt to inflate the existing disk size.


Q3) What is the disadvantage of configuring VM direct path I/O for a virtual machine ?

If we configured VM direct path I/O, the virtual machine gains significant performance improvement as it is provided direct access through the adapter, however, it loses it’s virtualization features and the adapter cannot be used by other virtual machines.


Q4) Does vSphere provide support for the currently version of VMware Site Recovery Manage version 1.0 ?

vSphere has does not support SRM version 1.0 at this present moment.


Q5) What is the benefit of using a Distributed vSwitch as compared to a Standard vSwitch ?

With a distributed virtual switch, the network statistics and policies of the virtual machine that has been vmotion to another ESX Server will migrate with the VM. This provides the ability for network vmotion and is useful for implementing inline intrusion detection systems and firewalls.


Q6) Does ESX 4 and ESXi 4 support jumbo frames and TSO ?

Yes, both ESX 4 and ESXi 4 provides support for jumbo frames as well as TSO, these can now be configured in the GUI as compared to VI3 where administrators could only do it via command lines.


Q7) What is the different between VMware Data Protection as compared to the traditional Vmware Consolidated Backup ?

VMware Data Protection supports all storage architecture for backup and restore via LAN and SAN. It also supports full, incremental and differential file level backup options.


Q8) What is the key driving factor for users adopting VMware vCenter Data Recovery ?

It’s an API that runs in a virtual machine within your vCenter, it provides agentless backup and can backup virtual machines even when they are being vmotion to a different host.


Q9) Can we perform Storage Vmotion now via the GUI inside vCenter ?

Yes, Storage Vmotion feature is now avaliable in the vSphere Client connected to vCenter Server. It provides full support for FC SAN and NFS.


Q10) When using vCenter Linked Mode feature, what are the functions that could be shared among the vCenters in this link ?

vCenter Linked Mode allows administrator to centrally manage all the vCenter within a single view, roles and licenses can be shared across the vCenters configured in a link.


Q11) Do I still require a Flexnet License Server if all my ESX Servers are ESX 4 and ESXi 4 ?

No, you no longer require a license server for the to manage the new ESX Servers. All licenses are managed within the vCenter Server.

Q12) If my customer has a hybrid environment where they still have ESX 3 and ESX 3.5, can vCenter communicate with the existing Flexnet License Server ?

Yes, vCenter can communicate with existing license servers so as to allow it to manage legacy ESX Servers. vCenter will pull the licenses for legacy hosts from the flexnet license server.


Q13) Why am I unable to hot add CPU and memory to virtual machine ?

You are required to enable this function under the virtual machine settings in order to use it. Therefore, it is advisable to enable it before you start your virtual machine for the very first time.


Q14) Is it true we can now use the new VMware Update Manager to upgrade our legacy ESX

Servers (For example: ESX 3.5) to ESX 4.0 version ?

Yes, the new VUM has the ability to upgrade your legacy ESX Server hosts for you. However, if you are upgrading a standalone host, you will be required to power off all virtual machines running on that host.


Q15) How come we are unable to use our existing VI Client to manage our ESX 4 and vCenter 4 ?

No, the legacy VI Client is unable to manage newer ESX Server Hosts and vCenter. You will need to install vSphere Client to manage newer ESX Server Hosts and vCenter as well as legacy ESX Hosts.


Q16) In vSphere, can we configure bidirectional CHAP authentication for iSCSI ?

Yes, we can now configure bidirectional CHAP authenticaton for iSCSI software. It is fully supported. Previously, we could only configure unidirectional CHAP authentication.


Q17) Do we still need to configure a Service Console port for iSCSI initiator ?

No, we no longer need a Service Console for software iSCSI initator. The vmkiscsid no longer runs in the Service Console. There have been improvements made to the new iSCSI stack in the kernel and also with the use of TCP/IP2 which has multi threading capabilities.


Q18) What is the maximum number of CPU and maximum amount of memory a virtual machine can scale ?

In vSphere, a virtual machine can now be configure with a maximum of 8 virtual CPUs and 255 GB of memory.

Q19) What is the maximum amount of logical CPUs and memory per ESX Server 4 host can scale ?

ESX Server 4 now supports a maximum of 64 logical CPUs and 1 TB of memory.


Q20) What actions allow us to configure thin disk provisioning for a virtual machine ?

When we create a new virtual machine, clone an existing virtual machine, clone a template or perform Storage Vmotion on an existing virtual machine.


Q21) What is the benefit of configuring thin disk provisioning as compared to thick disk

provisioning for a virtual machine ?

When we configure thin disk provisioning the virtual machine only uses the space that it requires and not the entire disk size, this allows the remaining unused space for other virtual machines. This enables us to do Storage Over-commitment and use the storage more efficiently.


Q22) Will my virtual machines still have connection if the virtual center that stores my Distributed vSwitch configuration goes down ?

Yes, this is because the Distributed vSwitch has an control plane which sits at the vCenter Server level and an I/O plane which are the form of hidden vSwitches sitting at the ESX level. Therefore, even if the vCenter goes down, virtual machines continue to have connectivity through the I/O plane at the ESX level.


Q23) What is the maximum number of ESX Hosts we can connect to a single distributed switch ?

We can connect up to 64 ESX hosts per distributed switch and vCenter 4 can support up a maximum of 16 distributed switches. Which means we can have up to 1024 hosts on these 16 distributed switches. Refer to “Configure Maximums” for more details.


Q24) What is the version of the 64 bit Service Console running in ESX 4 ?

The Service Console is a 2.6 linux kernel compatible with Red Hat Enterprise Linux 5.2 or CentOS 5.2 version.


Q25) What is the maximum number of uplinks or ports per ESX 4 or ESXi 4 Host ?

The maximum number of uplinks per ESX 4 or ESXi 4 Host is 32 uplinks. Refer to “Configure Maximums” for more details.


Q26) Can we install vCenter Server on a 64 bit Windows OS ?

Yes, vCenter Server can be installed on both 32-bit and 64-bit Windows OS. Refer to “Compatibility matrix” for more details.


Q27) Does ESX/ESXi 4 supports round robin multipathing policy ?

Yes besides fixed (preferred) and most recently used (MRU), ESX/ESXi 4 now supports round robin multipathing policy and it has to be configured on the storage level.


Q28) Can vCenter 4 support a cluster which includes ESX 3.x and ESX 4 hosts ?

Yes, we can cluster legacy ESX 3.x hosts and ESX 4 hosts together in the same cluster. vCenter will have to connect to the flexnet license server to manage the licenses for the legacy hosts. However, new features such as hot add and PCI pass through may not be avaliable to the VMs on legacy hosts. Refer to “Upgrade Guide” for more details.


Q29) When upgrading from virtual center 2.x to vCenter 4, is there downtime for the host and do we need to re add the ESX hosts back into the inventory ?

No, there’s no time for the hosts and existing hosts will remain in the inventory. However, there will be downtime for virtual center. Remember to backup the databases as during the upgrade process, the database schemas are changed and in the event of a upgrade failure, you will not be able to roll back and you will have to do a restore. Refer to “Upgrade Guide” for more details.


Q30) When we hot add memory to a powered on VM, will the swap file get dynamically increased ?

When we hot add memory to a powered on VM, the swap file size will get dynamically increase.


Q31) When we hot add memory to a powered on VM and the swap file get dynamically increased,

what happens if there is not enough disk space to meet the growing vswap file size ?

You will not be able to add memory to that VM that has not enough memory for the swap file to grow and you will receive an error.


Q32) Can we add USB controllers to our VM in ESX/ESXi 4 ?

Yes, we now have the ability to hot plug USB controller into our VMs while they are running. However, the usb device has to be connected to the ESX Server and not the client local machine.


Q33) When installing convertor plug-in, I get a 404 error and the installation halts ?

During installation of vCenter Convertor you will have to enter the FQDN instead of the IP address or netbios name as this may cause you to receive the 404 error when installing the vCenter convertor plug-in later.


Q34) Where is Distributed Power Management configured and what are the protocols it uses ?

DPM is configured and managed at the DRS cluster level. It uses IPMI, ILO and Wake On LAN protocols. DRS can use DPM to put underutilized hosts into standby modes to save power consumption.


Q35) What is new with vCenter 4 user access and role management as compared to the virtual center 2.5 ?

vCenter 4 allows us the ability to assign administrators to inventory objects such as networks and datastores which were not available with the previous virtual center version.


Q36) What are the new tasks we can schedule in vCenter 4 task scheduler ?

vCenter 4 task scheduler allows us the ability to schedule a task to increase the resources in a resource pool or virtual machine. This would be good to cater to the needs of virtual machines that will require additional ad-hoc resources such as finance department doing month end closing which may result in resources surge on their machines.


Q37) How does VMware HA on an ESXi Server sends out heart beat if ESXi does not have a service console ?

VMware HA clusters configured for ESXi Servers uses the vmkernel present on all ESXi Servers to send and receive heart beats. Whereas, on ESX Servers the heartbeat is send and receive through the service console. Therefore, we may not want to cluster ESX and ESXi Servers together in the same cluster.


Q38) Can we create a cluster with ESX and ESXi Servers ?

Yes. However, VMware HA may not work as both servers uses different port groups to send out heart beats. Vmotion and DRS may still work. This is not a supported practise.


Q39) What is the limitation for configuring VMware Fault Tolerance for a virtual machine ?

Virtual machine selected for VMware FT must be provisioned with thick disk and not thin disk, if it was provisioned with thin disk, there will be a prompt to inflate the existing disk size.


Q40) How can I grow an existing VMFS LUN without creating an extent or physical partition ?

We can use the grow function to grow an existing VMFS LUN. If the LUN is out of space, first we must get the storage administrator to grow the same LUN on the storage level with storage array management utilities then within the vCenter Server, we can then select the LUN and grow it.


Q41) How come the hot add CPU and hot add memory option is greyed out for my VM ?

This feature is currently available only on supported guest OS such as Windows Server 2003 enterprise and

Windows 2008 datacenter edition. The type of license also plays a part on the availability of this feature to the VM.


Q42) What does the channel number stands for in vmhba#:T:C:L?

The only real example that I’ve seen in vSphere so far, is the software iSCSI initiator. If you give the VMkernel multiple VMkernel ports, and each port can reach (over its own subnet) different targets, they are listed with different “channel” numbers, to indicate whether they use the first VMkernel port, the second or the third.


Q43) Can we install VMware Consolidated Backup VCB in a virtual machine ?

Yes, VCB can now be installed in a VM and it can be use to backup VMs running on iSCSI and NFS. However,if you wish to backup VMs whose files reside on an FC San LUN, VCB must be installed on a physical machine.


Q44) Does VMware View 3 work with VMware vSphere 4 ?

No, currently VMware View 3 is only supported on VI 3.5 infrastructure and it is not supported to work with vSphere 4 environment.


Q45) Is the Service Console root file system still running on ext3 file system ?

No, the SC root file system is now running on VMDK and this is automatically created during initial installation of ESX Servers.


Q46) Is it possible to configure VMware Update Manager 4 to point to WSUS to grab windows updates ?

No, this is not possible as the VUM Server is unable to communicate with the WSUS Server.


Q47) Can vCenter 4 perform Storage Vmotion on a legacy ESX 3.x Host and convert the VM virtual disk from thick to thin disk ?

Yes, vCenter 4 is able to convert a VM’s virtual disk from thick to thin using storage vmotion. Refer to this “ESX 3.x and vCenter 4 SVmotion” for more detail discussion.


Q48) I understand that Oracle databases licensed by per CPU, how does that translate to the number of license I have to purchase if I port it over to VM ?

In order for you to run your Oracle DB within a VM on that ESX Server, you have to purchase license for each physical CPU on that ESX Server box. Refer to this “Oracle Licensing Per Processor” for more detail discussion.


Q49) How come there is no standalone boot CD for VMware Convertor 4.0 for me to download for use for cold cloning ?

VMware vCenter Converter Standalone 4.0.1 does not support cold cloning, you must use an earlier Converter edition boot CD 3.0.x Enterprise Edition. Refer to this “VMware Convertor User Guide” for more information.


Q50) When we convert a VM from thin disk to thick disk, which state must the VM be in to perform the request ?

The VM must be in the powered off state in order to be converted from thin to thick disk.


Q51) What is the default multipathing policy for ESX 4 ?

The hypervisor determines whether to use MRU or Fixed based on the type of arrays it detects. If array is active\passive, it would be treated as MRU. If array is active\active, it would be treated as fixed. Refer to “Multipathing Policies in ESX 4” for more details.


Q52) What is the difference between Enhanced vmxnet and vmxnet3 ?

Vmxnet3 is an improved version of enhanced vmxnet, some benefits and improvements are MSI/MSI-X support, Side Scaling, checksum and TCP Segmentation Offloading (TSO) over IPv6, off-loading and Large TX/RX ring sizes. Refer to “Vmxnet3 tips and tricks” for more details.


Q53) When we replicate the LUNs over resignaturing only occurs for VMFS LUNs and not RDM, how do we get the replicated RDM to work ?

You can replicate the RDM to a new array, but the mapping file that is configured on the vm itself will no longer be pointing to the same location it was previously, so the RDM has to be re-mapped to the VM in a DR scenario.


Q54) After installing plug-in inside the VC, I am unable to enable the plug-in and it always shows as disabled.

Go to services.msc ensure that the Virtual Center Management Webservices is running and then relogin the vSphere Client and enable the plug-in.


Q55) What is the difference between ephemeral and dynamic binding on a distributed virtual switch ?

Ephemeral a new port on every power-on. The port is destroyed when the VM disconnects from the port. Dynamic assign a port when the VM is powered on, it uses a concept similar to DHCP in that if the same port is available then it will renew that one. Refer to “Networking Deep Dive” for more details.


Q56) What is the difference between a thick virtual disk and eager zeroed thick virtual disk ?

Thick virtual disk does not format the VMDK at the time of deployment. This means that data, which needs to be written, must pause while the blocks required to store the data are zeroed out. An eager zeroed thick virtual disk actually formats all of its data blocks at the time of deployment.


Q57) What kind of permissions do we need to provide when configuring a NAS Server ?

We need to configure permission for the administrator group account rights on the NAS Server so that the ESX Server can access the NAS Server.


Q58) Storage View tabs in the SAN storage datastore is blank and does not show anything ?

Start the vCenter Mount Service and virtual disk service, then restart the vCenter Server service on the Windows OS. Then click on refresh for the storage view tabs.


Q59) Can we migrate VMs running on ESX host with VMware Hardware Version 7 to ESX host with VMware Hardware Version 4 ?

No we cannot migrate VMs running on hardware version 7 back to hardware version 4. VMware hardware version 7 only exists on ESX4 and greater. However, it is possible to migrate VMs running on ESX host with hardware version 4 to ESX host running on hardware version 7.


Q60) Does VMware have an online page where we can search for all the technical white papers ?

Yes. Please kindly refer to “Technical Resource Center” for more information.


Q61) Does VCB supports Windows Server 2008 ?

VCB version 1.5 supports Windows Server 2008. Refer to “VCB 1.5 Update 1” release notes for more information.

VMware Frequently Asked Questions

Q1) Can we use EMC PowerPath together with VMware NMP (Native Multi-pathing Plug-in) ?

It is not recommended to use both at the same time, we usually either use PowerPath or VMware NMP. Refer to “EMC PowerPath VE With VSphere” documentation for more details.


Q2) Can we use VMware Update Manager (VUM) to schedule upgrading of VMware tools on the VMs to meet latest ESX hardware version ?

Yes, this is possible with VMware Update Manager 4. We do not need to create a new baseline, there’s a default baseline that does this task.


Q3) Does Storage Vmotion use the Service Console to migrate running VMs live from one storage to another storage ?

Storage VMotion migrates VM via the Service Console network, this means that there’s no additional burden on the other Virtual Machine connection network.


Q4) Can we implement VMware Fault Tolerance on a VM with an existing VMware Snapshot on the VM ?

No, VMware FT does not support VM with existing snapshots. We have to merge or discard the snapshot before enabling VMware FT to protect that VM.


Q5) What is the protocol used by vCenter Linked Mode to link to other Virtual Center Servers ?

vCenter Management Server 4 uses LDAP via port 386 by default.


Q6) Does VMware supports installation of vCenter Server 4 on Windows Server 2008 R2 operating system platform ?

No, Windows Server 2008 R2 is not a supported platform for installing vCenter Server 4. Refer to “vSphere Compatibility Matrix” for details.


Q7) Is it possible to configure both thin provisioned virtual disk and thick provision virtual disk n a single VM, thus, creation of a VM with multiple virtual disks which have different provisioned modes virtual disk ?

Yes, this is possible.


Q8) When deploying thin provisioned virtual disk for VM, the virtual disk is expand on demand which creates many fragments which could be scattered across our datestore, what’s the way to defrag a VM with thin provisioned virtual disk ?

When performing Storage Vmotion migrating the VM to a different LUN and migrating the VM back to original datastore, the VM’s file will be fragmented.


Q9) During Scripted Installation of ESX Server 4, is it possible create local directory on the host and run scripts to install third party utilities from other vendors such as HP or Dell ?

Yes, it is possible to create a local directory to load packages then configure scripts to run pre or post installation of ESX Server. Refer to “Scripted Installation of ESX” for more information.


Q10) What’s the major different between virtual network adapter E1000 and VMXNET3 ?

VMXNET3 is the third generation of paravirtual network adapter by VMware. Includes features such as MSI/MSI-X support, Receive Side Scaling, IPv6 checksum and TCP Segmentation Offloading (TSO) over IPv6,

VLAN off-loading and Large TX/RX ring sizes. Refer to “vSphere Networking” guide and “E1000 and VMXNET3” discussion for more details.


Q11) Are we able to configure vCenter Server Heartbeat to keep replication and synchronization while disabling automatic failover and enabling only the option for a manual switch over ?

No, that is not possible with current version of vCenter Server Heartbeat.


Q12) If the local Windows OS running vCenter Server Heartbeat restarts after applying a security

patch, will the Primary vCenter Server trigger a failover to the Secondary vCenter Server ?

As the default ping for the channel network is 3 pings with 20 seconds interval between each ping, the failover will occur and Secondary vCenter Server will take control and start protected services. However, we are able to configure the ping intervals in the vCenter Server Heartbeat manage server console.


Q13) Can we import host profiles created on our master vCenter Server located in our main

datecenter to the vCenter Servers running in remote sites or branch offices ?

Yes, vCenter host profile configuration allows us to import host profiles created in virtual machine profile format .vpf into existing vCenter Servers that we wish to apply the host profiles.


Q14) Is it possible to configure a schedule task to stage ESX Server patching with VMware Update Manager?


No, this is not possible with the current version of VMware Update Manager 4.


Q15) When migrating VMs with Storage VMotion, could we choose different datastore LUNs if our single VM has multiple virtual disks ?

Yes, when performing Storage Vmotion of a running VM live from one storage to another storage, at the screen when we are prompted to select datastore, we could click on “advanced” tab to select different datastores for our virtual disks.


Q16) Does vCenter Server Heartbeat works across LAN and WAN ?

Yes, it works both across LAN and WAN. Refer to “vCenter Server Heartbeat Reference Guide” for more



Q17) What’s the main benefit of deploying ESXi 4.x Servers as compared to ESX 4 Servers in a datacenter production environment ?

There’s significantly less patches required for an ESXi Server as compared to ESX Server. As ESXi does not have a service console, it is relatively more secure and less vulnerable to attacks.


Q18) Is it advisable to run anti virus software on the Service Console on ESX Servers in production environment ?

Running anti virus softwares in Service Console will generally take up resources which might affect performance of the ESX Server as the anti virus software requires resources to run.


Q19) In terms of hardening the ESX Server from a security aspect, what’s the solution for

managing root accounts on ESX Server hosts ?

We could restrict root user account logins and password only to datacenter administrators. We could thancreate linux user accounts inside Service Console and then enable sudo permissions to grant these users shellaccess. We could also join ESX Server to Active Directory authentication.


Q20) Is there a new VMFS version with VMware vSphere ?

No, vSphere is still running on VMFS3 version. However, there is a change in virtual machine hardware to version 7.


Q21) What’s the maximum number of vCenter Servers we can configured in a linked mode ?

We can configure a total of 10 vCenter Servers in a vCenter Server linked mode. vCenter linked mode can manage up to 1000 ESX/ESXi Servers and 10000 virtual machines across 10 vCenter Servers in a single console.


Q22) What’s the main functions and capabilities when deploying vCenter Server linked mode ?

vCenter Server linked mode gives administrators a single pane of glass view, it allows administrators to share global roles and licenses across vCenter Servers.


Q23) What’s the rollback option tab when configuring vCenter Server Heartbeat ?

As vCenter Server Heartbeat uses Microsoft Virtual Shadow Copy Service (VSS) we could configure a rollback. Refer to help guide on the local vCenter Server after installation and configuration of vCenter Server Heartbeat for details.


Q24) What are the supported Microsoft SQL version that can be protected by vCenter Server Heartbeat 5.5 update 1 ?

vCenter Server Heartbeat is currently able to protects only Microsoft SQL Server 2005 SP1-SP3 and Microsoft SQL Server 2008 versions.


Q25) Can we use vCenter Server 4 to manage legacy ESX 3.x and 2.x Servers ?

Yes, vCenter Server 4 can only manage legacy ESX Servers if we configure connectivity to an existing flexnet license server as vCenter Server 4 does not manage the licenses for legacy host directly.


Q26) After joining ESX Servers to Active Directory domain, can we use distribution groups instead of user accounts ?

VMware does not support the add of AD groups but it does support the adding of individual users and PAM module. Refer to “ESX Authentication AD”


Q27) Will vCenter Server Heartbeat works together with vCenter Linked Mode ?

Yes, vCenter Server Heartbeat and vCenter linked mode is compatible with the most current version update

2. Adam components will be replicated active and passive, therefore, full functionality is available when switch

to target mode. Refer to “forum discussion” for more details.


Q28) Does vSphere 4 supports Microsoft Clustering VMs whose file resides on iSCSI LUN ?

No, this version of vSphere 4 is not compatible with iSCSI SAN for MSCS configuration. Refer to “Setup for Failover Clustering and MSCS” for more details.


Q29) When running resxtop command in vMA to view performance output, how do I view only VMs and not other worlds ?

After entering the resxtop command, we can enter “V” which will output displaying only VMs on that specific ESX Server.

Q30) If we set a memory limit of a VM to 400 MB and avaliable memory to 512 MB, what will happen after the VM reaches the limit ?

Based on the POC done in the class, the ballooning vmmemctl kicks in after the VM hits the 400MB limit. Thus, the remaining 112 MB of memory is not used.


Q31) Can we create a vmdk greater than 256 GB when configuring a block size of 1MB ?

No this is not possible, we will have to increase the block size before the vmdk size will be increased. For example, a block size of 2MB will allow us to create a 512GB vmdk and a block size of 4MB will allow us to create a vmdk that’s 1024GB. Refer to “Forum discussion” for more details.


Q32) Where can I create the session file within the vMA ?

Session file creation can be found within the vMA when we access $ cd /usr/lib/vmware-vcli/apps/session.


Q33) Does vCLI supports running on Linux and Windows OS ?

Yes, vCLI is supported and can be run from both Windows and Linux OS.


Q34) When can we use explicit failover on a vSwitch ?

We can select “use explicit failover” when we want vSwitch to always use the highest order uplink from the list of Active adapters which passes failover detection criteria such as link state only and beacon probing. Refer to “virtual switch policies” for more details.


Q35) What is the difference between consumed memory and active memory ?

Consumed memory is when there is no contention and active memory refers to the memory used when there is contention.


What is SWAP Partition?

To replace pages or segments of data in memory. Swapping is a useful technique that enables a computer to execute programs and manipulate data files larger than main memory. The operating system copies as much data as possible into main memory, and leaves the rest on the disk. When the operating system needs data from the disk, it exchanges a portion of data (called a page or segment ) in main memory with a portion of data on the disk.

DOS does not perform swapping, but most other operating systems, including OS/2, Windows, and UNIX, do. Swapping is often called paging or Virtual memory.

Windows :

Virtual memory has been a feature of Microsoft Windows since Windows 3.1 in 1991. 386SPART.PAR (or WIN386.SWP on Windows 3.11 and Windows for Workgroups) is a hidden file created by Windows 3.x for use as a virtual memory swap file. It is generally found in the root directory, but it may appear elsewhere (typically in the WINDOWS directory). Its size depends on how much virtual memory the system has set up under Control Panel – Enhanced under “Virtual Memory.” If a user moves or deletes this file, Windows will BSoD (Blue Screen of Death) the next time it is started with “The permanent swap file is corrupt” and will ask the user if they want to delete the file (It asks whether or not the file exists).

Windows 95 uses a similar file, except it is named WIN386.SWP, and the controls for it are located under Control Panel – System – Performance tab – Virtual Memory. Windows automatically sets the page file to be 1.5 x physical memory. This page file is located at C:\\pagefile.sys on all NT – based versions of Windows (including Windows 2000 and Windows XP). If you run memory intensive applications on a low physical memory system it is preferable to manually set the size to a value higher than default. Additionally, fixing the size of the swap file will prevent it from being dynamically resized by Windows. This resizing causes the swap file to become fragmented, resulting in reduced performance. This page file cannot be defragmented withWindows’ built-in defragmenting tools, such as ntfsdefrag.

Virtual Memory in Linux:

In Linux operating system, it is possible to use a whole partition of the HDD for virtual memory. Though it is still possible to use a file for swapping, it is recommended to use a separate partition, because this excludes chances of fragmentation, which reduces the performance of swapping. A swap area is created using the command mkswap filename/device , and may be turned on and off using the commands swapon and swapoff, respectively, accompanied by the name of the swap file or the swap partition.

In order to additionally increase performance of swapping, it is advisable to put the swap partition at the beginning of the HDD, because the transfer speed there is somewhat higher than at the end of the disk. There were also some successful attempts to use the memory located on the videocard for swapping, as modern videocards often have 128 or even 256 megabytes of RAM.

What are the different types of virtualization?

Server Virtualization – consolidating multiple physical servers into virtual servers that run on a single physical server.

Application Virtualization – an application runs on another host from where it is installed in a variety of ways. It could be done by application streaming, desktop virtualization or VDI, or a VM package (like VMware ACE creates with a player). Microsoft Softgrid is an example of Application virtualization.

Presentation Virtualization – This is what Citrix Met frame (and the ICA protocol) as well as Microsoft Terminal Services (and RDP) are able to create. With presentation virtualization, an application actually runs on another host and all that you see on the client is the screen from where it is run.

Network Virtualization – with network virtualization, the network is “carved up” and can be used for multiple purposes such as running a protocol analyzer inside an Ethernet switch. Components of a virtual network could include NICs, switches, VLANs, network storage devices, virtual network containers, and network media.

Storage Virtualization – with storage virtualization, the disk/data storage for your data is consolidated to and managed by a virtual storage system. The servers connected to the storage system aren’t aware of where the data really is. Storage virtualization is sometimes described as “abstracting the logical storage from the physical storage.

Happy Birthday Blog!

The blog turned one year this month and I just can’t believe how quickly one year has passed by. Hope I get time and resource to perform some R&D and post interesting content following year. I have mostly captured details that would help me and I’m loading it to my blog for quick access. I will be very delighted if you find it useful.

Thank you for reading and others who just left spam comments in my blog 😀 . I look forward to another great year with more VMware virtualization information to share! A special thank you also goes out to other bloggers and VMware virtualization community members for sharing your time and knowledge and continuing to inspire me to do the same.