Samselvaprabu's questions

We are using below command to figure out the IP addresses which are down (which is free IP address to use)

nmap -v -sn -n 192.168.1.0/24 -oG - | awk '/Status: Down/{print $2}'

I wanted to get a subrange within that . For example the above command shows all the free IP address from 192.168.1.1 to 192.168.1.124. [ Note: This is for test automation and we are using static IP addresses. Multiple team members are sharing range of IP addresses but often overstep other's range. So this will help us to decide whether IP is really free at that moment before using it)

But I want to find free IP address within the range of

192.168.1.55 to 192.168.1.65

. How to do it?

we have connected few Iscsi volumes. When we execute

Get-IscsiConnection

it shows connection between target IP address and initiator IP address.

But when we execute

mpclaim.exe -s -d

It shows the different values. When i enquired about this my seniors said that this is path not connection.

What is Path ? How it differs from connection?

In our storage array we change the discovery IP. Once the discovery IP is changed, the Multipath connection has to be rebalanced (It should make connection again with new discovery ip). But it is not rebalanced. We had to do Rescan disk and Iscsi deep discovery.

We found diskpart command to rescan disk

(rescan | diskpart)

but we could not find a way to do Iscsi deep discovery. How to do Iscsi deep discovery? Is there any powershell cmdlet to do it?

We were experimenting MPIO with our Storage array. We saw the Get-Iscsisession and Get-Iscsiconnection cmdlet to find the paths created. But during IO ,i would like to know which path has been used. Is it possible? Which tool can be used to check that? I am using Windows 2016 as Operating system. We connect to our storage via Iscsi initiator.

We have created few volumes in storage array. Via Iscsi initiator those volume have been added into host machine which is Windows 2012 R2. For few volumes when we delete the contents ,the volume size is not reduced in the storage array side. But the disk content is deleted from host side. In the array side when we verify there is no unmap stats. So we suspect that from host side there is no unmap event is triggered.

How to find whether UNMAP request is raised from windows host? we are checking event viewer, but don't know how to look for UNMAP request. Can some one help?

I am trying to defrag the volume by optimize-volume cmdlet . I have passed mount point path. But it fails as below.

PS C:\Users\Administrator> Optimize-Volume -Path C:\Testvol1\disk
Optimize-Volume : No MSFT_Volume objects found with property 'Path' equal to 'C:\Testvol1\disk'.  Verify the value of the property and retry.
At line:1 char:1
+ Optimize-Volume -Path C:\Testvol1\disk
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : ObjectNotFound: (C:\Testvol1\disk:String) [Optimize-Volume], CimJobException
    + FullyQualifiedErrorId : CmdletizationQuery_NotFound_Path,Optimize-Volume

How to pass path for Optimize-volume? Or is there any other way to defrag using mounthpath available?

I am trying to get disk number of particular volume. This volume is mapped into filepath instead of drive letter.

I am able to get uniqueid of volume from Get-volume cmdlet

$Volumepath = 'C:\MappedVolume2\disk2'
$uniqId = (get-volume -FilePath $Volumepath).UniqueId
Get-Disk -UniqueId $uniqId

This doesn't display any output or error.

This volume exists and UniqId displaying something like below

\?\Volume{0874487c-28c3-4c65-a374-b022fa07b20a}\

But unable to get any details. I need to get the disk number of volume.

Update:

I execute below commands

 > get-disk  | select UniqueId
   2036BB19DB62D3166C9DB900D48FC2BE
 > Get-Volume | select UniqueId
   \\?\Volume{0874487c-28c3-4c65-a374-b022fa07b20a}\

though they are named as uniqueid ,they are totally different. So they will not be compatible. Is there any other way to get disk number of volume ?

I have mapped IScsi volumes into my windows 2016 server. I have created disk out of them. Now i need to find whether the disk is thin provisioned or not.

I am trying with below cmdlets

Get-Disk and Get-PhysicalDisk

But no luck. How to find whether the disk is thin provisioned or not using powershell?

We are having VMware ESXi 4.1 and we need to move to ESXi 5.1 or ESXi 5.5.

Before upgrade some of our team members advised us to take a backup of VMs.

Now the problem is we don't have SAN or Net app storage. We are having another ESXi server with enough space to hold 15 VMs.

We are having VMs with snapshots.

Using VMware converter i can copy those VMs to the back up server. But i am not sure whether it will take backup of our snapshots as well.

Do we need to take backup before upgrade? If needed to take backup which mechanism is better to take backup with snapshots.

I am having two virtual machines with same OS and software list. (In fact they were cloned).

Now I have installed an application in a VM and taken a snapshot.

Is it possible to copy this snapshot and associate with the another VM?

(So that i don't need to spend the effort again. I know i can clone but if i can just paste and associate the snapshot it would be better ) .

If not possible , little explanation about why it is not possible would be more helpful. (I need to answer my manager)

I read in one of the VMware KB articles that snapshots will directly affect VM performance.

But my team keeps asking me how snapshots can affect performance.

I would like to give them solid reason behind the statement the snapshots are performance killers.

Can anyone explain a little bit theory about how snapshots are actually affecting the performance? Is it just because Disk I/O rate of hard disk would be slow?

We have an ESXi 4.1 server with 48 GB RAM.

For each VM, we are allocating 4GB of memory. Since the server will have 13 virtual machines, my manager thinks this is wrong.

I am going to explain to them that ESXi will actually manage memory itself, but they asked me how much memory I allocated for the ESXi server itself.

I did not allocate any (I have not even heard of an option for allocating memory for the ESXi server itself).

How is memory allocated for ESXi server? How does it over-allocate/distribute RAM among virtual machines without issue?

We have renamed our machine [Windows 2008 R2] name and it asked for restart. we did it.

But still we are able to ping the old machine name and it responds.

Strange thing is even we are able to ping the new machine name and it also responds.

[I checked that whether it is different machine or not by verifying the IP address. But IP address is same. So it should be the same machine]

How it occurs? How to make it recognize only new machine name?

If some scripts are run, our application should work even after machine rename.

But we are unable to test this as we are unsure whether machine rename takes effect.

we are using Esxi 4.1. One of the VM is there in datastore which could not be deleted due to the files were locked.

We were trying to reload the VM into inventory by creating new VM with custom option(there we would be given option to select existing virtual disk). But we were unable to select that.

I think as it is locked , we were either unable to delete or load it again?

How to delete the file completely?

I am using VMware ESXi. In our team we use to provide snapshots for long term backup.

Then we faced issues like memory spillover and the server got hang up.

I started reading in VMware knowledgebase articles and everywhere. Everywhere it was recommended not to have snapshots for a long time.

Even VMware advised to keep snapshots for maximum of three days.

But our team kept asking us to have at least two permanent snapshots (till deleting the VM). Sometimes we may use the VM for a year).

1. one snapshot is for fresh machine state. (So when we complete testing an application, we will revert back to fresh state and install another application) (If I did not allow that, I may often need to host the VM.)

2. Next snapshot for keeping the VM in some state (maybe they would have found an issue and keep that state for some time. Or they may install prerequisites for the application and keep the machine ready for testing.)

Logically, their needs seems to be fair. But if I allow that, I am to permit them to hold the snapshots for long time. We are not using our VM as a mail server or database server.

Why is keeping snapshots for long time having an adverse effect?

Why are snapshots considered as temporary backups, not real backups?

I am using ESXi 4.1. I am a having VM with 3 snapshots.

When exploring datastore , snapshot vmdk name doesn't contain any word from snapshot name.

How to find snapshot vmdk for corresponding snapshot?

For ex. "ie88nt8ksvm081-000004.vmdk"

Does the above vmdk means it is the 4th snapshot in hierarchy?

I am using ESXi 4.1. I got following errors often. I used to delete some of the snapshots i am having and will temporarily solve this issue.

My datastore shows it has more than 400 GB of free space. But still it occurs. Whether datadisk free information is bogus? What is the root cause for this issue? How to solve this permanently?

We have created a VM and took a snapshot.

Then we made changes in that VM and made it as domain controller. That state also saved in snapshot.

Now i want to lock the snapshot. My intention is that i should not deleted that snapshot by mistake.

Is it possible to lock the snapshot? Or if i delete all snapshots, will it be merged with base VM?

We have given our users privilege to take snapshots. But now it is uncontrollable and people started taking meaningless snapshots and never deleting it.

Due to this we are facing performance issue, Disk space overloaded issue and etc.

I would like to prevent users from taking snapshots beyond certain limit. For example. Users may not be allowed to take more than 3 snapshots .

How to achieve this? ( We are using ESXi 4 and ESXi 4.1 and VMware Vsphere )

If it can't be prevented , atleast is there a mechanism to alert me when user creating more than 3 snapshots?

We are having VMware ESXi servers. VMs will be assigned to user and they will use RDP to use it. We are unable to find whether the users are really using them or the VMs are idle.

Is there any way to find it?