Category: Virtualization

RabbitMQ Memory Limit

RabbitMQ has an memory limit, then RabbitMQ hits this limit weird things starts to happen. Example The .NET library for RabbitMQ Client hangs then you try to dispose the connection.

How do you know that RabbitMQ has run out of memory? you have to check the RabbitMQ node (picture below)

Then Memory is read you are out of memory

RabbitMQ will not allocate all available memory in the VM or container you have set up.

High memory watermark blocks publishers and prevents new messages from being enqueued. Since garbage collection can double the memory used by a queue, it is unsafe to set the high memory watermark above 0.5. The default high memory watermark is set to 0.4 since this is safer as not all memory is used by queues. This is entirely workload specific, which differs across RabbitMQ deployments.

https://www.rabbitmq.com/memory-use.html

A freshly started RabbitMQ uses roughly 100MB, that means that you cannot limit your container to less than 250MB of memory if you want your RabbitMQ to actually be useable

Autostart a Virtual Machine in Xenserver

1. Enable poweron on pool
xe pool-list
xe pool-param-set uuid=89d4a986-2b3e-e771-b6d3-9a6cad4b7e52 other-config:auto_poweron=true
xe pool-param-list uuid=89d4a986-2b3e-e771-b6d3-9a6cad4b7e52
2. Enable poweron on Virtual Machine
xe vm-list
xe vm-param-set uuid=de89d51b-e581-553f-992d-f0a5044dccd2 other-config:auto_poweron=true
xe vm-param-list uuid=de89d51b-e581-553f-992d-f0a5044dccd2

OpenMediaVault / Debian network configuration for bonding/lacp and vlan

This is an example of an network configuration on my OpenMediaVault server. It takes two network interfaces (eth3 and rename3) and bonds them together using LACP. On top off this bond i have created three bridges. br1 witch is for untagged traffic and. br641 and 642 for vlan tagged traffic on vlan 641 and 642 respectively. br1/br641/br642 are all attached to the host and is configured for dhcp. they can also be attached to virtual machines.

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KVM With usb/pci passthrough

Creating a Virtual Machine for Windows 10

virt-install \
    --name=Windows10-VM1 \
    --ram=4096 \
    --cpu=host \
    --vcpus=2 \
    --os-type=windows \
    --os-variant=win7 \
    --disk /srv/dev-disk-by-label-SSD/kvm/Windows10-VM1,size=200,sparse=true,bus=virtio \
    --disk /zfs-pool-1/kvm/iso/Windows10.iso,device=cdrom,bus=ide \
    --disk /zfs-pool-1/kvm/iso/virtio-win.iso,device=cdrom,bus=ide \
    --network bridge=br0 \
    --graphics vnc,listen=0.0.0.0 

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