LINUX AND VMWARE STUFF

This Blog is to share our knowledge and expertise on Linux System Administration and VMware Administration

Monday, December 21, 2015

Upgrade VMware Tools without reboot

Monday, December 21, 2015 0
Upgrade VMware Tools, selected virtual machine:

Get-Cluster "Productie" | Get-VM "vmname" | Update-Tools –NoReboot

Get VMware-Tools versions:

Get-View -ViewType VirtualMachine | select Name, @{ Name=”ToolsVersion”;

Expression={$_.config.tools.toolsVersion}}
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Troubleshooting Syslog Collector in VMWare vsphere

Monday, December 21, 2015 0
Whenever syslog files aren’t updating  in the repository from he vSphere Syslog Collector server.










Here are some basic steps that can be used to troubleshoot this problem.
VMware ESXi hosts

On the VMware ESXi hosts check the following settings:
– Syslog destination. Open the vSphere Client. On the ESXi server, open the configuration tab and select advanced Settings. Check the Syslog.global.logHost value. The format is: protocol://FQDN:port . For example udp://syslog.beerens.local:514


















– Is the ESXi firewall port open for syslog traffic. Open the vSphere Client, on the ESXi server, open the Configuration tab, select Security Profile, Firewall and select Properties. Check if the syslog service is enabled.

















 vSphere Syslog Collector
On the vSphere Syslog Collector server check the following settings:
– Is the syslog port 514 (default) listening:


-  Reload and update the syslog configuration.  On the ESXi host use the following command:
esxcli system syslog reload
– Is the Syslog Collector service started. Restart the Syslog Collector service if needed 












After the reloading the syslog settings and restarting the Syslog Collector service the files begun to update again in the repository.
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How to Enable Execute Disable/No Execute CPU feature at ESXI

Monday, December 21, 2015 0

ESXi requires the Execute Disable/No Execute CPU feature to be enabled

Restart the host, enter in(press F9) to boot in BIOS mode.

 Advanced Options --> Processor Options --> No-Execute Memory Protection, then configure: Enabled


image

 

Hope it helps.
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VMware: How to rollback ESXi 5.1 to 5.0

Monday, December 21, 2015 0
Whenever you find issues after upgrading  to esxi 5.1 from 5.0 , rollback is as simple as below.

 Reboot the host and press R to start the Recovery Mode..
Installed hypervisors:
HYPERVISOR1: 5.0.0-623860
HYPERVISOR2: 5.1.0-799733 (Default)
CURRENT DEFAULT HYPERVISOR WILL BE REPLACED PERMANENTLY
DO YOU REALLY WANT TO ROLL BACK?

 Press Y to start the roll back

 image

 Result:
image
The host is downgraded and back online again with VMware vSphere ESXi 5.0.0
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How to Disable the interrupt remapping on ESXi

Monday, December 21, 2015 0
 ESXi/ESX 4.1

To disable interrupt remapping on ESXi/ESX 4.1, perform one of these options:

    Run this command from a console or SSH session to disable interrupt mapping:

    # esxcfg-advcfg -k TRUE iovDisableIR

    To back up the current configuration, run this command twice:

    # auto-backup.sh

    Note: It must be run twice to save the change.

    Reboot the ESXi/ESX host:

    # reboot

    To check if interrupt mapping is set after the reboot, run the command:

    # esxcfg-advcfg -j iovDisableIR

    iovDisableIR=TRUE
    In the vSphere Client:
        Click Configuration > (Software) Advanced Settings > VMkernel.
        Click VMkernel.Boot.iovDisableIR, then click OK.
        Reboot the ESXi/ESX host.

ESXi 5.x and ESXi 6.0.x

ESXi 5.x and ESXi 6.0.x does not provide this parameter as a GUI client configurable option. It can only be changed using the esxcli command or via the PowerCLI.


    To set the interrupt mapping using the esxcli command:

    List the current setting by running the command:

    # esxcli system settings kernel list -o iovDisableIR

    The output is similar to:

    Name          Type  Description                              Configured  Runtime  Default
    ------------  ----  ---------------------------------------  ----------  -------  -------
    iovDisableIR  Bool  Disable Interrupt Routing in the IOMMU   FALSE        FALSE    FALSE

    Disable interrupt mapping on the host using this command:

    # esxcli system settings kernel set --setting=iovDisableIR -v TRUE

    Reboot the host after running the command.

    Note: If the hostd service fails or is not running, the esxcli command does not work. In such cases, you may have to use the localcli instead. However, the changes made using localcli do not persist across reboots. Therefore, ensure that you repeat the configuration changes using the esxcli command after the host reboots and the hostd service starts responding. This ensures that the configuration changes persist across reboots.
    To set the interrupt mapping through PowerCLI:

    Note: The PowerCLI commands do not work with ESXi 5.1. You must use the esxcli commands as detailed above.

    PowerCLI> Connect-VIServer -Server 10.21.69.233 -User Administrator -Password passwd
    PowerCLI> $myesxcli = Get-EsxCli -VMHost 10.21.69.111
    PowerCLI> $myesxcli.system.settings.kernel.list("iovDisableIR")

    Configured  : FALSEDefault     : FALSE
    Description : Disable Interrrupt Routing in the IOMMU
    Name        : iovDisableIR
    Runtime     : FALSE
    Type        : Bool

    PowerCLI> $myesxcli.system.settings.kernel.set("iovDisableIR","TRUE")
    true

    PowerCLI> $myesxcli.system.settings.kernel.list("iovDisableIR")

    Configured  : TRUEDefault     : FALSE
    Description : Disable Interrrupt Routing in the IOMMU
    Name        : iovDisableIR
    Runtime     : FALSE
    Type        : Bool
    After the host has finished booting, you see this entry in the /var/log/boot.gz log file confirming that interrupt mapping has been disabled:

    TSC: 543432 cpu0:0)BootConfig: 419: iovDisableIR = TRUE
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How to resolve - vCenter Server task migration fails with the error: Failed to create journal file provider, Failed to open for write

Monday, December 21, 2015 0
For vCenter Server

The journal files for vCenter Server on Windows are located at:

    Windows 2003 and earlier – %ALLUSERSPROFILE%\Application Data\VMware\VMware VirtualCenter\journal\
    Windows 2008 and later – %PROGRAMDATA%\VMware\VMware VirtualCenter\journal\

Whenever you..

    Cannot perform provisioning operations, such as vMotion, Clone, storage DRS
    Cannot create new virtual machines.
    Cannot add RDM disk to a virtual machine.
    Provisioning operations (such as vMotion, Clone, or Migrate) fail.
    vCenter Server task migration fails. You see the error:

    A general system error occurred: Failed to create journal file providerFailed to open "<filename>" for write   

Cause

This issue occurs if there is not enough free disk space to store the journal information. The management components in vCenter Server and ESX/ESXi record transactions to journal files when tracking long-running operations. The path and filename cited in the error message indicate the layer that failed to create a journal file.

The Resolution should be ..

Delete or archive the unnecessary files on this filesystem to free up disk space. Depending on your vCenter Server implementation, it is recommended to have a minimum of 40GB of disk space free on the system.



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Explain about VSS writers in Virtual Machines and how to disable the specific VSS writers with VMware Tools

Monday, December 21, 2015 0
VMware products may require file systems within a guest operating system to be quiesced prior to a snapshot operation for the purposes of backup and data integrity.
VMware products which use quiesced snapshots include, but are not limited to, VMware Consolidated Backup and VMware Data Recovery.
As of ESX 3.5 Update 2, quiescing can be done by Microsoft Volume Shadow Copy Service (VSS), which is available in Windows Server 2003.


Operating systems which do not have VSS make use of the SYNC driver for quiescing operations. When VSS is invoked, all VSS providers must be running. If there is an issue with any third-party providers or the VSS service itself, the snapshot operation may fail.
Before verifying a VSS quiescing issue, ensure that you are able to create a manual non-quiesced snapshot using the vSphere Snapshot Manager.


With vSphere 4.0, VMware introduced the ability to disable specificVSS writers for the benefit of troubleshooting a specific VSS writer issue.

If you experience an issue backing up a specific virtual machine using snapshot technology and you have identified an issue with a specific VSS writer within the virtual machine, this blog  explains how to disable that VSS writer from being called during a snapshot operation.

To disable a specific VSS writer being called during a snapshot operation:

    Determine the name of the VSS writer that you want to exclude from the snapshot operation. Run this command from within Windows:
    vssadmin list writers
    Note: With Windows Vista, 7, and 2008 the command prompt may need to be run with administrator elevation.

    You see output similar to:

    Writer name: 'Task Scheduler Writer'
       Writer Id: {d61d61c8-d73a-4eee-8cdd-f6f9786b7124}
       Writer Instance Id: {1bddd48e-5052-49db-9b07-b96f96727e6b}
       State: [1] Stable
       Last error: No error
    Note: The name of the VSS Writer is highlighted.

    Create or edit the vmbackup.conf file which is located at %ALLUSERSPROFILE%\Application Data\VMware\VMware Tools\ .

    Note: If the vmbackup.conf file does not exist then create it.
    Place the name of the VSS writer you want to disable on a separate line. If you want to disable more than one VSS writer, ensure that you place each VSS writer name on a separate line. For example:
    Task Scheduler Writer
    NTDS
    SqlServerWriter
    Microsoft Exchange Replica Writer
    Microsoft Exchange Writer
    Restart the VMware Tools service.
    When the writer issue has been resolved, you can remove the offending writer from the vmbackup.conf file.

Note: VMware does not provide these VSS writers. Engage the provider of the VSS writer to troubleshoot the writer issue to ensure application consistency with the writer.
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Wednesday, December 9, 2015

Explain about SysRq command and How to reboot the hanged physical Linux & Xen Linux VM Server

Wednesday, December 09, 2015 0
The magic SysRq key is a key combination in the Linux kernel which allows the user to perform various low level commands regardless of the system’s state.

It is often used to recover from freezes, or to reboot a computer without corrupting the filesystem. The key combination consists of Alt+SysRq+commandkey. In many systems the SysRq key is the printscreen key.

First, you need to enable the SysRq key, as shown below.

echo "1" > /proc/sys/kernel/sysrq

List of SysRq Command Keys

Following are the command keys available for Alt+SysRq+commandkey.

    ‘k’ – Kills all the process running on the current virtual console.
    ‘s’ – This will attempt to sync all the mounted file system.
    ‘b’ – Immediately reboot the system, without unmounting partitions or syncing.
    ‘e’ – Sends SIGTERM to all process except init.
    ‘m’ – Output current memory information to the console.
    ‘i’ – Send the SIGKILL signal to all processes except init
    ‘r’ – Switch the keyboard from raw mode (the mode used by programs such as X11), to XLATE mode.
    ‘s’ – sync all mounted file system.
    ‘t’ – Output a list of current tasks and their information to the console.
    ‘u’ – Remount all mounted filesystems in readonly mode.
    ‘o’ – Shutdown the system immediately.
    ‘p’ – Print the current registers and flags to the console.
    ‘0-9′ – Sets the console log level, controlling which kernel messages will be printed to your console.
    ‘f’ – Will call oom_kill to kill process which takes more memory.
    ‘h’ – Used to display the help. But any other keys than the above listed will print help.

Perform a Safe reboot of Linux

To perform a safe reboot of a Linux computer which hangs up, do the following. This will avoid the fsck during the next re-booting. i.e Press Alt+SysRq+letter highlighted below.
  •     unRaw (take control of keyboard back from X11,
  •     Terminate (send SIGTERM to all processes, allowing them to terminate gracefully),
  •     Kill (send SIGILL to all processes, forcing them to terminate immediately),
  •     Sync (flush data to disk),
  •     Unmount (remount all filesystems read-only),
  •     Reboot.
VM Server

 To perform a safe reboot of a Linux Xen Virtual Server which hangs up, do the following. This will avoid the fsck during the next re-booting.

Run the below command in Xen Dom0.

#xm sysrq <domainid> s
#xm sysrq <domainid> u
#xm sysrq <domainid> b


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