Scratch location set to /scratch – vSAN node on SD card

At the place I work, we experienced continuous “The ramdisk ‘root’ is full” issues on our vSAN ESXi nodes.

The first thing we did was to raise a support call and have vmware check what is filling up the ramdisk.

Support suggested that we need to limit the size of vsantraces to 200MB, and pointed to the below KB Article

This puzzled me, as the vsantraces was not full.

Ramdisk Size Used Available Use% Mounted on
root 32M 32M 0B 100% --
etc 28M 5M 22M 18% --
opt 32M 368K 31M 1% --
var 48M 728K 47M 1% --
tmp 256M 492K 255M 0% --
iofilters 32M 0B 32M 0% --
hostdstats 1553M 17M 1535M 1% --
snmptraps 1M 0B 1M 0% --
vsantraces 300M 167M 132M 55% --

I kept digging and I found out that the scratch partition on the hosts was not pointing scratch -> /tmp/scratch

but it was on / instead.

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Home Lab Environment

Setting up the Home Lab Environment

The main reason behind building a Lab at Home, like many others also do, is to help me study and learn.

The specification of the hardware I used for the Lab can be found here.

To give you a better understanding of the setup and the nesting that is happening, I have drawn the below diagram. You can see that everything is on a single physical machine running VMware ESXi 6.0 U2, and the picture below represents the logical design of my lab. A physical switch, a physical server, and everything else virtual.

Logical Design

Vgnosis Logical Design


The Main Lab “Infrastructure” Setup

Let’s outline what our basic infrastructure components will be for the Lab.

Hostname OS Description Hardware
vgnosisesx01 Vmware ESXi 6.0U2 vGnosis Physical ESXi Host HP Proliant DL360 G7
vgnosis2k01 Windows 2012 R2 vGnosis Domain Controller and DNS Virtual Machine
vgnosisvap01 Virtual Appliance – SLES 11 vGnosis PSC (Platform Services Controller) Virtual Machine
vgnosisvap02 Virtual Appliance – SLES 11 vGnosis VCSA (vCenter Server Appliance) Virtual Machine
vgnosis2k03 Windows 2012 R2 vGnosis VUM (Vmware Update Manager) Virtual Machine
sw01 Cisco IOS vGnosis Cisco Switch Cisco WS-C3750E-48PD
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Platform Services Controller (PSC) Replication Latency – Enhanced Linked Mode

At work, we have deployed a  PSC / VCSA 6U1  in Singapore, and linked it to our London PSC on the same domain,

so we can use Enhannced Linked Mode.

Below diagram diagram describes the PSC / VCSA deployment.



Tried to logon to VCSA01 which is in our London vSphere and it took 10 minutes for the web client to load.

VCSA02 which is in Singapore appeared on the screen and couldn’t be expanded.

Hosts and Clusters on VCSA01 didn’t show any tabs. So, Web Client wasn’t responding as it should, and couldn’t do any work.

c# client worked OK.

As soon as we powered off PSC02 / VCSA02, Web client started responding as it should.


It seems that PSC replication is affected by high latency, which in our case is ~ 200ms.


Question here is why VMware or any of the nice blogs around hasn’t got any maximum latency numbers around PSC replication.

We have based a design around Enhanced Linked Mode with our upgrade to vsphere 6 around the globe, if latency is an issue we need to change everything.


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My Lab – Hardware

The Kit I use for my Lab:


HP Proliant DL360 G7



CPU Cores: 12 CPUs x 2.666 GHz

Processor Type: Intel(R) Xeon(R) CPU X5650 @2.67GHz

Processor Sockets: 2

Cores per Socket: 6

Logical Processors: 24

Hyperthreading: Active

Number of NICs: 4

Memory: 288GB (16x16384MB @1333MHz


Cisco Catalyst 3750E-48 2x10GE









TP-Link Archer C7 AC1750



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