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I will show how to use ZFS instant snapshotting and cloning functionality to effortlessly clone a running postgres database regardless of its size. Setup Install your Linux OS of choice then ZFS and Postgres. I use Centos 7 but most commands used in this post are distro-indipendent. Create a zfs pool called tank or use whatever name suits you. In the pool create a filesystem called pgdata . For the sake of following a minimalist ZFS best practice apply the following settings: zfs set compression=lz4 tank/pgdata zfs set xattr=sa tank/pgdata

I was recently asked to recover a mirth instance whose embedded database had grown to fill all available space so this is just a note-to-self kind of post. Btw: the recovery, depending on db size and disk speed, is going to take long. The problem A 1.8 Mirth Connect instance was started, then forgotten (well neglected, actually). The user also forgot to setup pruning so the messages filled the embedded Derby database until it grew to fill all the available space on the disk. The SO is linux. The solution First of all: free some disk space so that the database can be started in embedded mode from the cli. You can also copy the whole mirth install to another server if you cannot free space. Depending on db size you will need a corresponding amount of space: in my case a 5GB db required around 2GB to start, process logs and then store the temp files during shrinking. Then open a shell as the user that mirth runs as (you're not running it as root, are you?) and cd in...

When developing applications for the cloud everybody knows (or should know) that a host, network or disk (in short any resource) failure is not an exceptional event but a rather common one. A resource failure becomes a 'normal', common event in the application lifecycle like the occasional bug. The Amazon approach is that some services (like databases) come with a certain degree of resiliency built-in while others (i.e. EC2 instances) are expected to fail relatively frequently and it is left to the developer to install backup, redundancy and availability countermeasures. My understanding is that other providers, like Rackspace , have instead a more traditional approach and will automatically restart failed virtual servers in case of host failure. If the failed cloud server image cannot be recovered then it will be bootstrapped from the most recent backup. This means that, depending on the requirements, one could move a traditional application to the cloud without having to...