From b6ffe890003bcaab1dcb0eaefcb6762d0069f1ac Mon Sep 17 00:00:00 2001
From: SquirePug <42793435+SquirePug@users.noreply.github.com>
Date: Wed, 25 Sep 2019 12:08:43 +1000
Subject: Added vyos on vmware page and rudimentary structure. (#118)

* feature: adding notes for running on vmware around contending memory and memory management in low memory situations
---
 docs/appendix/vyos-on-vmware.rst | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)
 create mode 100644 docs/appendix/vyos-on-vmware.rst

(limited to 'docs/appendix')

diff --git a/docs/appendix/vyos-on-vmware.rst b/docs/appendix/vyos-on-vmware.rst
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+.. _vyosonvmware:
+
+Running on VMWare ESXi
+######################
+
+ESXi 5.5 or later
+*****************
+
+.ova files are available for supporting users, and a VyOS can also be stood up using a generic Linux instance, and attaching the bootable ISO file and installing from the ISO 
+using the normal process around `install image`.
+
+.. NOTE:: There have been previous documented issues with GRE/IPSEC tunneling using the E1000 adapter on the VyOS guest, and use of the VMXNET3 has been advised.
+
+Memory Contention Considerations
+--------------------------------
+When the underlying ESXi host is approaching ~92% memory utilisation it will start the balloon process in s a 'soft' state to start reclaiming memory from guest operating systems. 
+This causes an artifical pressure using the vmmemctl driver on memory usage on the virtual guest. As VyOS by default does not have a swap file, this vmmemctl pressure is unable to
+force processes to move in memory data to the paging file, and blindly consumes memory forcing the virtual guest into a low memory state with no way to escape. The balloon can expand to 65% of 
+guest allocated memory, so a VyOS guest running >35% of memory usage, can encounter an out of memory situation, and trigger the kernel oom_kill process. At this point a weighted 
+lottery favouring memory hungry processes will be run with the unlucky winner being terminated by the kernel.
+
+It is advised that VyOS routers are configured in a resource group with adequate memory reservations so that ballooning is not inflicted on virtual VyOS guests.
+
+
+
+
+
+References
+----------
+
+https://muralidba.blogspot.com/2018/03/how-does-linux-out-of-memory-oom-killer.html
+
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