Brushing over some of the following topics a couple of days out from VCAP-DCA.

vscsiStats

vscsiStats is a tool with allows you to capture scsi performance counters per VM at the vmkernel level. ie How much IO is your VM pushing, what size are the IO, Latency, etc.

Below is a quick run down on recording some statistics with vscsiStats and then pushing it to CSV.

First identify the VMs world ID you want to capture statistics for:

vscsiStats -l

Out put will be something similar to this:

Virtual Machine worldGroupID: 2847194, Virtual Machine Display Name: vCenter Orchestrator, Virtual Machine Config File: /vmfs/volumes/5506c1e3-200ffed2-de82-20cf308d4a74/vCenter Orchestrator/vCenter Orchestrator.vmx, {

Virtual SCSI Disk handleID: 8211 (scsi0:0)

The world ID I highlighted and underlined is the identifier for the VM we wish to capture statistics for. You can then use the following command to start the capture for this VM:

vscsiStats -s -w 2847194

Now this will notify you that it has started, you can push the results to console by doing the following:

vscsiStats -w 2847194 -p all -c

or you can push the statistics recorded so far to a CSV by doing the following:

vscsiStats -w 2847194 -p all -c /tmp/vco_vscsi_results.csv

Once you believe you have recorded enough data with vscsiStats you can do the following to stop it:

vscsiStats -x

Make sure to remember to STOP IT. It will keep running even unless you do this. When you push it out to a csv that is just what it has captured so far so you could do it again before stopping it and you will have more data.

Password Policies

There are two places within vSphere you can modify password policies. One is for SSO and the other is for console logins to hosts.

To do this you will need to be logged into administrator@vsphere.local The SSO password policy can be modified by going to the Web Client > Administration > Single Sign On > Configuration

From here you have three tabs which you are able to modify different things

To modify console user password policies you can edit the following config: /etc/pam.d/passwd

There is no real reason to explain the different strengths as this VMware KB does it perfectly, just thought I should mention it: Click Here

Flash Read Cache

Flash read cache is a feature added in vSphere 5.5 which allows you to accelerate VM vmdk performance by using local flash storage as a cache for a VMDK on a VM or multiple VMDKs. It is configured Per VMDK.

The cache is created at VM startup, can be moved between hosts during vMotion and is obviously more beneficial to read intensive workloads.

It’s an enterprise PLUS feature and is fully supported by DRS/HA in your cluster. DRS will have a lower move priority for VMs configured with this and will only move them if it is REQUIRED to correct cluster load.

You need to configure an SSD as a “Flash Resource” and you can then utilize this for a flash read cache for VMDKs or you are also able to use it as a local swap cache for your ESXi host.

To configure a Flash Resource you require a minimum of 1 local SSD in your host.