No coredump target has been configured

I was doing a hardware upgrade for some of the VMWare hosts in lazy fashion. I pulled the disk (small SATA SSD) from old host (HP BL460c Gen8) and inserted it into new host (HP BL460c Gen9). The old hosts used SAS HBA and the new hosts are using integrated SATA controller.

Using this method I avoided the unnecessary re-installation of the hosts. But when they booted I got warning message – “No coredump target has been configured. Host core dumps cannot be saved.”

Update 12.08.2016 – Starting from ESXi 5.5 U3 build 4179633 this issue will fix it self automatically. You can read more from here.

I turned to KB article 2004299 to fix it but I had to do a little more than described there.

My fix process was following:

  • Logged in to ESxi via SSH
  • esxcli system coredump partition get returned – “Not a known device: naa.xxxxxxxxxxxxxxxxxxxxxxxxxxx”
  • Executed following command to list all the disks and find the SSD disk I was booting from: esxcli storage core path list | more
  • My SSD disk was “Runtime Name: vmhba0:C0:T0:L0”, “Device: t10.ATA_____MO0100EBTJT_____________________________S0RFNEAC603385______”
  • Executed following command to list partitions on my disk –  “esxcli storage core device partition list -d t10.ATA_____MO0100EBTJT_____________________________S0RFNEAC603385______”
  • Identified that my coredump partition is number 7 (type fc)
  • Executed following command to set the partition: esxcli system coredump partition set –partition=”t10.ATA_____MO0100EBTJT_____________________________S0RFNEAC603385______:7″
  • Executed the following command to activate the partition: esxcli system coredump partition set –enable true
  • esxcli system coredump partition get now returns and the warning message dissipated:
    Active: t10.ATA_____MO0100EBTJT_____________________________S0RFNEAC603385______:7
    Configured: t10.ATA_____MO0100EBTJT_____________________________S0RFNEAC603385______:7

 

128GB DDR4-2400 Memory Kit available for HPE servers

HPE has made available 128GB (1x128GB) Octal Rank x4 DDR4-2400 CAS-20-18-18 Load Reduced Memory Kit (HPE info page). The price as of writing this (13.07.2016) is quite high – 9499 USD.

The 128GB RAM module open up possibilities to build single socket systems with up to 1,5TB of RAM.

Example HP ProLiant DL380 Gen9 config:

  • 1 x Intel Xeon E5-2699v4 (2.2GHz/22-core/55MB/145W)
  • 12 x HPE 128GB (1x128GB) Octal Rank x4 DDR4-2400 CAS-20-18-18 Load Reduced Memory Kit

Reducing the number of sockets could lower the amount of software licenses needed – eg VMWare.

Virtual Machine network latency issue

Recently we were debugging an issue where VM network latency was higher than usual on some VMs as soon as vCPU was utilized. When CPU was loaded we were seeing ping response times up to 30ms in the same VLAN. Normal value usully is below 0.5ms. After several failed attempts one of my colleagues found a thread on SUSE Forums which described the issue we were having – https://forums.suse.com/archive/index.php/t-4308.html. From the thread we found a hint – VM advanced setting called “sched.cpu.latencySensitivity”. On problematic VMs this option was set to “low”. It was the exactly this issue in our environment as well – all problematic VMs had this setting set to “low”. We shut downed the VMs and changed “sched.cpu.latencySensitivity” setting value to “normal” and the issue was fixed. Now the latency is constantly below 0.5ms.

To check value for individual VM you can use Web Client or following command:
Get-VM -Name <VMNAME> | Get-AdvancedSetting -Name sched.cpu.latencySensitivity

If the response is empty then the setting does not exist and I guess “normal” value is used.

To check this setting on all VMs I used this script (developed from script I got from this page):
Get-VM | Select Name, @{N=”CPU Scheduler priority”;E={
($_.ExtensionData.Config.ExtraConfig | `
where {$_.Key -eq “sched.cpu.latencySensitivity”}).Value}}

To fix the setting through PowerCli I used this script (developed from script I got from this page):
Get-VM -Name “VMNAME” | Get-View | foreach {
$ConfigSpec = New-Object VMware.Vim.VirtualMachineConfigSpec
$OValue = New-Object VMware.Vim.optionvalue
$OValue.Key = “sched.cpu.latencySensitivity”
$OValue.Value = “normal”
$ConfigSpec.extraconfig += $OValue
$task = $_.ReconfigVM_Task($ConfigSpec)
Write “$($_.Name) – changed”
}

We found several other VMs where this setting was set to “low”. Currently we don’t have any idea why some VMs had this setting set to low. There is a VMWare Community thread where at least two other persons claiming that they have faced similar issues with this setting.

Corrupted server profile in HP blade server after firmware upgrade

Recently we ere applying a SPP 2016.04 for some our blade servers. After upgrade one the server did not have network. From ESXi console everything looked OK. Tried cold boot – nothing. Tried downgrade of Emulex CNA firmware – nothing. Tried latest Emulex firmware again – nothing. Finally turned off server, went to VCEM (Virtual Connect Enterprise Manager) and edited the faulty profile by just clicking edit and then saved the profile again. Powered up the server and now everything was OK. I guess firmware update somehow damaged the profile and by re-applying the profile using VCEM it got fixed.

Change tracking target file already exists

After upgrading to VMWare ESXi 5.5 U3 we started seeing random snapshot errors during backups with following message – “An error occurred while saving the snapshot: Change tracking target file already exists.”. Issue is caused by leftover cbt file that is not deleted when snapshot is removed by backup software.

After submitting several logs and traces to VMWare they acknowledged that issue exists and it will be fixed for ESXi 5.5 in June patch release and for ESXi 6.0 in July patch release.

Right now when we detect a problematic VM we browse the datastore and delete the leftover cbt file.

ScaleIO 2.0 now available

EMC has released ScaleIO 2.0 couple of days ago. More information – https://community.emc.com/docs/DOC-52581

Some new features (source ScaleIO 2.0 release notes):

  • Extended MDM cluster – introduces the option of a 5-node MDM cluster, which is able to withstand two points of failure.
  • Read Flash Cache (RFcache) – use PCI flash cards and/or SSDs for caching of the HDDs in the SDS.
  • User authentication using Active Directory (AD) over LDAP.
  • The multiple SDS feature – allows the installation of multiple SDSs on a single Linux or VMware-based server.
  • Oscillating failure handling – provides the ability to handle error situations, and to reduce their impact on normal system operation. This feature detects and reports various oscillating failures, in cases when components fail repeatedly and cause unnecessary failovers.
  • Instant maintenance mode – allows you to restart a server that hosts an SDS, without initiating data migration or exposing the system to the danger of having only a single copy of data.
  • Communication between the ScaleIO system and ESRS (EMC Secure Remote Support) servers is now supported – this feature replaces the call-home mechanism. It allows authorized access to the ScaleIO system for support sessions.
  • Authenticate communication between the ScaleIO MDM and SDS components, and between the MDM and external components, using a Public and Private Key (Key-Pair) associated with a certificate – this will allow strong authentication of components associated with a given ScaleIO system. A Certificate Authority certificate or self-signed certificate can be used.
  • In-flight checksum protection provided for data reads and writes – this feature addresses errors that change the payload during the transit through the ScaleIO system.
  • Performance profiles – predefined settings that affect system performance.

ScaleIO can be downloaded from EMC website – http://www.emc.com/products-solutions/trial-software-download/scaleio.htm. ScaleIO 2.0 supports VMWare (5.5 and 6.0), Linux and Windows.

More info about ScaleIO 2.0 can be found from Chad Sakac blog: http://virtualgeek.typepad.com/virtual_geek/2016/03/scaleio-20-the-march-towards-a-software-defined-future-continues.html

Check out all of my posts about ScaleIO from here.

Storage vMotion fails on ESXi 5.5 for VMs with large memory reservation

I was doing some storage migrations and in one of the clusters Storage vMotions failed with a message: Failed to resume destination VM: msg.vmk.status.VMK_MEM_ADMIT_FAILED. 

Relocate virtual machine failed

After closer look I found that all those VMs that failed had a big memory reservations (192GB and 256GB). The ESXi 5.5 host only had 512GB of RAM. I will not go the topic why those reservations were set, but to successfully Storage vMotion those VMs I temporarily removed those reservations. After that Storage vMotion was successful. My guess is that VMWare check during Storage vMotion does the destination host (even though during Storage vMotion destination host was the same as source) has enough resources for this VM and if it does not it will fail the migration.