How To See Local RAID in ESXi 5.1

One of my work colleagues Mat Smith pointed out that when you install the generic ESXi hypervisor from the VMware site you get basic HP or Dell hardware information which is OK, but if you only have local storage you don’t know what state the underlying RAID configuration is in unless you have access to iLO or DRAC.

ESXi01 Hardware

This can be easily rectified by downloading the latest HP Custom Image for ESXi 5.1.0 ISO at the time of writing this blog post, the latest update is VMware-ESXi-5.1.0-799733-HP-5.34.23.iso

Once you have downloaded the ISO go into Update Manager > Admin View > ESXi Images and Select Import ESXi Image

ESXi Images 1

Select your the HP Custom Image for ESXi 5.1.0 ISO and click Next

ESXi Images 2

It should only take a minute or so and you will see the HP Custom Image for ESXi 5.1.0 ISO has been uploaded.  Once done hit next.

ESXi Images 3

Next we need to create a a baseline image, I’m going to roll with HP Custom Image ESXi 5.1.0 then click Finish

ESXi Images 4

Fingers crossed you should see the Imported Image

ESXi Images 5

Next we are going to go the Hosts and Clusters View and select the Update Manager Tab and then select Attach

ESXi Images 6

Select you Upgrade Baseline image and click Attach

ESXi Images 7

Next select Scan & choose Upgrades and then select Scan again

ESXi Images 8

Suprisingly enough after the scan completes you will notice that your ESXi Hosts are no longer compliant

ESXi Images 9

I tend to perform Baseline Upgrades on ESXi Hosts individual, rather than at Cluster level, just in case anything goes wrong.  With this in mind, go to your first ESXi Host and Select Remediate

Remediate 01

Select Upgrade Baseline and choose HP Custom Iage ESXi 5.1.0 and hit Next

Remediate 02

Accept the EULA and hit Next

Remediate 03

Woah, whats this message? ‘Remove installed third party software that is incompatible with the upgrade, and continue with remediation?  Word of warning you might want to check with your IT team to make sure that you aren’t going to lose any functionality.

Remediate 04

Enter a Task Name & Description and hit Next

Remediate 05

On the Host Remediation Options, make sure you tick ‘Disable any removable media devices connected to the virtual machines on the host’ as we don’t want an attached ISO to be the cause of our failure.  When you are ready hit Next

Remediate 06

On the Cluster Remediation Options, I tend to make sure that DPM is disabled and also Admission Control so that the ESXi Host can actually be patched.  Then click Next

Remediate 07

Once you are happy with your Upgrade Baseline, click Finish.  Time to go and make a brew as this is going to take along time!

Remediate 08

Awesome now that’s completed, we can see the Local Storage on the ESXi Host.

Storage View

Rinse and repeat for the rest of your ESXi Hosts.

Performance Increase? Changing Software iSCSI Adapter Queue Depth

I had an interesting point raised on the blog today from Colin over at He suggested changing the IOPS=QUE_DEPTH to see if I can decrease my storage latency.  I wasn’t able to find any settings to alter the queue depth on HP StoreVirtual and I’m not fortunate enough to have a Fiber channel SAN kicking around, so I don’t have the ability to change an HBA setting.  However this got the grey matter whirring , what about changing the Software iSCSI Queue Depth in ESXi5.1?

Before we get into the testing, I think it’s an idea to go over how a block of data gets from a VM to the hard disks on your NAS/SAN.

  1. Application e.g. Word Document
  2. Guest VM SCSI queue
  3. VMKernel
  4. ESXi vSwitch
  5. Physical NIC
  6. Physical Network Cable
  7. iSCSI Switch Server Port
  8. iSCSI Switch Processor
  9. iSCSI Switch SAN Port
  10. Physical Network Cable
  11. iSCSI SAN Port
  12. iSCSI Controller

I actually feel sorry for the blocks of data, they must be knackered by the time they are committed to disk.

At the moment I’m sending 1 IOP down each iSCSI path to my HP StoreVirtual VSA.  The results of this was an increase in overall IOPS performance, but an increase in latency see blog post Performance Increase? Changing Default IOP Limit

The Software iSCSI Queue Depth can be verified by going into ESXTOP and pressing U (LUN)

SSDVOL02 is naa.6000eb38c25eb740000000000000006f which has a Disk Queue Depth of 128

Disk Queue Length

IOMeter will let us know the overall latency which is what the Guest OS sees, which is great, but what we care about is knowing where the latency is happening.  This could be in one of three places:

  1. Guest VM SCSI queue
  2. VMKernel
  3. Storage Device

I have spun up a Windows 7 test VM, which has 2 vCPU and 2GB RAM.  Again for consistency I’m going to use the parameters set out by

The Windows 7 test VM is the only VM on a single RAID 0 SSD Datastore.  It is also the only VM on the ESXi Host.  So we shouldn’t expect any latency due to compute resources being in constraint.

We are going to use ESXTOP to measure our statistics using d (disk adapter) u (LUN) and v (VM HDD) and collate these with the IOMeter results.

The focus is going to be on DAVG/cmd KAVG/cmd and QAVG/cmd these are related to

DAVG/cmd  is Storage Device latency.

KAVG/cmd is VMKernel Device latency

GAVG/cmd is the total of DAG/cmd and KAVG/cmd

QAVG/cmd is Queue Depth of our iSCSI Software Adapter

Storage DEPTH

Taken from Interpreting ESXTOP Statistics

‘DAVG is a good indicator of performance of the backend storage. If IO latencies are suspected to be causing performance problems, DAVG should be examined. Compare IO latencies with corresponding data from the storage array. If they are close, check the array for misconfiguration or faults. If not, compare DAVG with corresponding data from points in between the array and the ESX Server, e.g., FC switches. If this intermediate data also matches DAVG values, it is likely that the storage is under-configured for the application. Adding disk spindles or changing the RAID level may help in such cases.’

Our Software iSCSI Adapter is vmhba37

Note that for the ESXTOP statistics, I took these at 100 seconds into each IOMeter run.

Default 128 Queue Depth

128 Queue Depth Results

Right then let’s make some changes shall we.

I’m going to run the command esxcfg-module -s iscsivmk_LunQDepth=64 iscsi_vmk which will decrease our Disk Queue Depth to 64.

This will require me to reboot ESXi03 so I will see you on the other side.


Let’s verify that the Disk Queue Depth is 64 by running ESXTOP with the U command.


Altered 64 Queue Depth

64 Queue Depth Results

Let’s run the command esxcfg-module -s iscsivmk_LunQDepth=192 iscsi_vmk which will increase our Disk Queue Depth to 192.  Then reboot our ESXi Host.

Again, we need to verify that the Disk Queue Depth is 192 by running ESXTOP with the U command.


Altered 192 Queue Depth

192 Queue Depth Results

So the results are in.  Let’s compare each test and see what the consensus is.

Comparison Results – IOMeter

The table below is colour coded to make  it easier to read.

RED – Higher Latency or Lower IOPS

GREEN – Lower Latency or Higher IOPS

YELLOW – Same results

IOMeter Results

Altering the Software iSCSI Adapter Queue Depth to 64 decreases latency by an average of 3.51%.  IOPS are increase on average by 2.12%

Altering the Software iSCSI Adapter Queue Depth to 192 decreases latency by an average of 3.03%.  IOPS are increase on average by 2.23%

Comparison Results – ESXTOP

The table below is colour coded to make  it easier to read.

RED – Higher Latency or Lower IOPS

GREEN – Lower Latency or Higher IOPS

YELLOW – Same results

ESXTOP Results

Altering the Software iSCSI Adapter Queue Depth to 64 decreases latency between Storage Device and Software iSCSI Initiator by an average of 0.06%.  VMKernel latency is increased by 501.42%.

Altering the Software iSCSI Adapter Queue Depth to 192 increases latency between Storage Device and Software iSCSI Initiator by an average of 6.02%.  VMKernel latency is decreased by 14.29%.

My Thoughts

The ESXTOP GAVG compares to the latency experienced by IOMeter for 32KB Block 100% Sequential 100% Read and 32KB Block Sequential 50% Read 50% Write.  I could put the differences down to latency in the Guest VM iSCSI queue. 

However, the differences between ESXTOP GAVG and IOMeter for 8KB Block 40% Sequential 60% Random 55% Read 35% Write and 8K Block 0% Sequential 100% Random 70% Read 30% Write are vastly different.  If anyone has some thoughts on this, that would be appreciated.

Overall altering the Software iSCSI Adapter Queue Depth to 64 gave a slightly performance increase for IOPS and latency, however not enough for me to warrant changing this full time in the lab.

Final note, you should always follow the advice of your storage vendor and listen to there recommendations when working with vSphere.

How To Configure WOL ESXi5

Distributed Power Management is an excellent feature within ESXi5, it’s been around for a while and essentially migrates workloads to fewer hosts to enable the physical servers to be placed into standby mode when they aren’t being utilised.

Finance dudes like it as it saves ‘wonga’ and Marketing dudettes like it as it give ‘green credentials’.  Everyone’s a winner!

vCenter utilises IPMI, iLO and WOL to ‘take’ the physical server out of standby mode.  vCentre tries to use IPMI first, then iLO and lastly WOL.

I was configuring Distributed Power Management and thought I would see if a ‘how to’ existed and perhaps my  ‘Google magic’ was not working, as I couldn’t find a guide on configuring WOL with ESXi5.  So here it is, let’s crack on and get it configured.

Step 1

First things first, we need to check our BIOS supports WOL and enable it.  I use a couple of HP N40L Microservers and the good news is these bad boys do.

WOL Boot

Step 2

vCenter uses the vMotion network to send the ‘magic’ WOL packet.  So obviously you need to check that vMotion is working.  For the purposes of this how to, I’m going to assume you have this nailed.

Step 3

Check you switch config. Eh don’t you mean my vSwitch config Craig? Nope I mean your physical switch config.  The ports that your vMotion network plugs into need to be set to ‘Auto’ as for WOL to work the ‘magic’ with certain manufacturers this has to go over a 100Mbps network connection.


Step 4

Now we have checked our physical environment, let’s check our virtual environment.  Go to your ‘physical adapters’ to determine if WOL is supported.

This can be found in the vSphere Web Client (which I’m trying to use more) under Standard Networks > Hosts > ESXi02 > Manage > Networking > Physical Adapters


We can see that every adapter supports WOL except for vmnic1.

Step 5

So we need to check our vMotion network to ensure that vmnic1 isn’t being used.

Hop up to ‘virtual switches’ and check your config.  Good news is I’m using vmnic0 and vmnic2 so we are golden.


Step 6

Let’s enable Distributed Power Management. Head over to vCenter > Cluster > Manage > vSphere DRS > Edit and place a tick in Turn ON vSphere DRS and select Power Management.  But ensure that you set the Automation Level to Manual. We don’t want servers to be powered off which can’t come back on again!


Step 7

Time to test Distributed Power Management! Select your ESXi Host, choose Actions from the middle menu bar and select All vCenter Actions > Enter Standby Mode


Ah, we have a dialogue box appear saying ‘the requested operation may cause the cluster Cluster01 to violate its configured failover level for high availability.  Do you want to continue?’

The man from delmonte he says ‘yes’ we want to continue!  The reason for the message is my HA Admission Control is set to 50%, so invoking a Host shut down is violating this setting.


vCenter is rather cautious and quite rightly so.  Now it’s asking if we want to ‘move powered off and suspended virtual machines to other hosts in the cluster’.  I’m not going to place a tick in the box and will select Yes.


We have a Warning ‘one or more virtual machines may beed to be migrated to another host in the cluster, or powered off, before the requested operation can proceed’.  This makes perfect sense as we are invoking DPM, we need to migrate any VM’s onto another host.


A quick vMotion later, and we can now see that ESXi02 is entering Standby Mode


You might as well go make a cup of tea as it takes the vSphere Client an absolute age to figure out the host is in Standby Mode.


Step 8

Let’s power the host back up again.  Right Click your Host and Select Power On

WOL 10

Interestingly, we see the power on task running in the vSphere Web Client, however if you jump into the vSphere Client and check the recent tasks pane, you see that it mentions ‘waiting for host to power off before trying to power it on’

WOL 11

This had me puzzled for a minute and then I heard my HP N40L Microserver boot and all was good with the world.  So ignore this piece of information from vCenter.

Step 9

Boom our ESXi Host is back from Standby Mode

WOL 12

Rinse and repeat for your other ESXi Hosts and then set Distributed Power Management to Automated and you are good to go.

How To Change Default IOP Limit

After my last blog post, I realised I hadn’t actually walked you threw how to change the default IOP limit used by Round Robin.

To crack on and do this we need a SSH client such as Putty

Each change, only has to be made per Datastore which makes things a little easier.

SSH to your ESXi Host and enter your credentials.  We are going to run the command to give us the Network Address Authority names of our LUN’s.

esxcli storage nmp device list | grep naa


A quick look in the vSphere Web Client shows us which Datastores the NAA belong too.


In my case, I want to change the settings for all of the Datastores.  So we will start by checking the current multi path policy to ensure it’s set to Round Robin and the default IOP maximum limit.  Let’s run the following command:

esxcli storage nmp psp roundrobin deviceconfig get -d naa.6000eb3b4bb5b2440000000000000021

A bit like ‘Blue Peter’ here is one I did earlier! Not very helpful.


Let’s run the same command again but for a different NAA.


Excellent, to change the default maximum IOP limit to 1 enter this command

esxcli storage nmp psp roundrobin deviceconfig set -d naa.6000eb39c167fb82000000000000000c –iops 1 –type iops

To check, everything is ‘tickety boo’ enter

esxcli storage nmp device list | grep policy

You should see that each Datastore default maximum IOP limit is set at 1


Performance Increase? Changing Default IOP Maximum

I was reading Larry Smith JR’s blog post on Nexentastor over at El Retardo Land and I didn’t know that you could change the default maximum amount of IOPS used by Round Robin.

By default vSphere allows 1000 IOPS down each path before switching over to the next path.

Now, I wanted to test the default against 1 IOP down each path, to see if I could eek some more performance out of the lab.

So before we do this, what’s our lab hardware?

ESXi Hosts

2 x HP N40L Microserver with 16GB RAM, Dual Core 1.5GHz CPU, 4 NICs


1 x HP ML115 G5 with 8GB RAM, Quad Core 2.2GHz CPU, 5 NICs

1 x 120GB OCZ Technology Vertex Plus, 2.5″ SSD, SATA II – 3Gb/s, Read 250M using onboard SATA Controller


1 x HP 1910 24G

And for good measure the software?

ESXi Hosts

2 x ESXi 5.1.0 Build 799733 using 2 x pNIC on Software iSCSI Initiator with iSCSI MPIO

1 x Windows Server 2008 R2 2GB RAM , 1 vCPU, 1 vNIC


1 x HP StoreVirtual VSA running SANiQ 9.5 with 4GB RAM, 2vCPU, 4 vNIC


1 x HP v1910 24G

Let’s dive straight into the testing shall we.

Test Setup

As I’m using a HP StoreVirtual VSA, we aren’t able to perform any NIC bonding, which in turn means we cannot setup any LACP on the HP v1910 24G switch.

So, you may ask the question why test this as surely to use all the bandwidth you need them to be in LACP mode.  Yep, I agree with you, however, I wanted to see if changing the IOP limit per path to 1, would actually make any difference in terms of performance.

I have created an SSD Volume on the HP StoreVirtual VSA which is ‘thin provisioned’.

Volume Details

From this I created a VMFS5 datastore in vSphere 5.1 called SSDVOL01.


And set the MPIO policy to Round Robin.


VMF-APP01 is acting as our test server and this has a 40GB ‘thinly provisioned’ HDD.


We are going to use IOMeter to test our performance using the parameters set out under

Test 1

IOP Limit – 1000

SANiQ v9.5

Test 1

Test 2

IOP Limit – 1

SANiQ v9.5

Test 2

Test 1 v 2 Comparison

Test 1 Comparison

We can see that we get extra performance at the cost of higher latency.  Now let’s upgrade to SANiQ v10.0 AKA LeftHand OS 10.0 and perform the same tests again and see what results we get as HP claim it to be more efficient,

Test 3

IOP Limit – 1000

LeftHand OS10.0 (SANiQ v10.0)

Test 3

Test 1 v 3 Comparison

Test 1v3  Comparison

HP really have made the LeftHand OS 10.0 more efficient some very impressive results!

Test 4

IOP Limit – 1

LeftHand OS10.0 (SANiQ v10.0)

Test 4

Test 2 v 4 Comparison

Test 2v4 Comparison

Overall, higher latency for slightly better performance.

Test 1 v 4 Comparison

Test 1v4 Comparison

From our original configuration of a 1000 IOPS Limit per path and SANiQ 9.5.  It is clear that an upgrade to LeftHand OS10.0 is a must!


I think the results speak for themselves, I’m going to stick with the 1 IOP limit on LeftHand OS10.0 as even though the latency is higher, I’m getting a better return on my overall random IOPS.