Author Archives: roger

CockroachDB vs Postgres-BDR

We have been happily using Postgres-BDR for years as a multi-master database for fault-tolerant applications – it’s been incredibly robust for us. The advantage of a multi-master database is that… Read more »

HAProxy option redispatch & backup servers

When we’re creating an API with fault-tolerance, to reduce the number of single points of failure, we often use Postgres BDR, a multi-master database, which allows us to provide two… Read more »

How to migrate large VMWare VMs to remote data-centers using rsync

Using VCenter’s migration over the internet to a remote data-center is often too slow for practical purposes – a 200GB VM may take several hours to move and that may… Read more »

VM disk performance across datastores

Here are some disk performance measurements (made on a Windows 10 VM on vSphere 6.5 with CrystalDiskMark) across different types of datastore (local SSD array, NFS (sync), NFS (async) and… Read more »

Blocking access to an ip address

Sometimes you need to block access to a specific ip address for test purposes – for instance to simulate unavailability of a web-service. Here’s how to do it on macOS… Read more »

Moving Docker container data

If you have created a container without specifying a volume, Docker will create one for you. If you later decide you’d rather have the container’s data somewhere else, you can… Read more »

Repairing a broken Postgres-BDR cluster

Postgres-BDR is an excellent multi-master replication clustering extension for PostgreSQL (https://www.2ndquadrant.com/en/resources/postgres-bdr-2ndquadrant/). We often use it for fault tolerant systems – its asynchronous and uncomplicated to set up (at least if… Read more »