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NFS is production ready | LV2 will have lower guarantees

This year we introduced NFS for highly available file volumes and LV2 for very fast local block storage.

NFS is worry-free, just use NFS

NFS is sufficiently complete that its the second service to be marked production ready in the product specification and the first to come with a money back guarantee. It is fully single-zone redundant with active/passive failover and automatic snapshots. This is the default storage everyone should be using. It offers complete worry free file storage that works with most docker containers out of the box. NFS is also accessible via webdav and S3. This allows easy collaboration on file based workloads.

Later this year we're planning to make snapshots explicitly controlled by users, so that you can instantly rollback yourself instead of asking customer support to do it.

LV2 requires special attention

Some customers prefer "virtual disks" instead of file storage. The primary advantage is that they're generally faster for single process workloads. There are several different ways to implement "virtual disks". If a competitor does not tell you which technology they use, it is very likely what we call LV1, that is locally redundant (RAID) storage directly attached to the host. In case of a host failure, the volume becomes unavailable and the associated pod will not be rescheduled.

With LV2 we tried to approach similar high availability and guarantees to our HA system, but ultimately the two worlds are just too dissimilar, and customers have much lower expectations. Instead we are reducing high availability of LV2 for the benefit of much quicker launch times. Users may choose to either restore from cold storage with a Recovery Point Objective of 1 Hour, or wait for manual recovery of the host (usually within a business day).

If you look out there you may notice that services like AWS EBS or Hetzners CEPH volumes offer much lower RPO than krauds LV2. This is because they're network volumes, not directly attached. These products are very unpopular, so we currently do not offer them. The primary disadvantage is that network storage has a significant latency penalty, at which point you might just use NFS.

However, if you would like to see zero RPO block volumes at kraud, let us know!

get ready to move your pods to Berlin


Earlier this year we semi-announced the intention to move to a new datacenter location. Kraud is on a mission to build carbon negative infrastructure, and the current datacenter provider misrepresented the origin of their elecricity in a way that does not align with our values.

The new location is 3U Telecom in Berlin. 3U Holding, the parent company of 3U Telecom is heavily invested in renewable energy, and we hope to have found a partner that shares our vision.

We also picked new network partners, , Core-Backbone, and BCIX, significantly increasing the connection quality of the new site.

We spent half a year building out the new site with an entirely new storage architecture based on ZFS. The old site had extremly poor IOPS and frequent total cluster freezes due to bugs in ceph. We can now offer LV2 storage with half a million IOPS, and automatic instant snapshots. A huge shift away from thinking first about compute to thinking first about storage.

The old site will be shut in July, so please prepare your workloads asap.


Moving pods with no storage attached is easy. Just delete the container and relaunch with the zone label -l The site will become default in july, after which you need to specify -l to launch a pod in the legacy zone.

If you have storage attached, moving is slighly more involved. We currently recommend moving from rbd to lv2 and from gfs to nfs, as this will most likely match your expectations.

  1. stop all pods
  2. create a new volume with docker volume create myvol --driver nfs
  3. copy all the files from the old to the new volume, for example by using webdav or with docker exec, depending on your use case.
  4. delete the old volume with docker volume rm oldvol
  5. recreate your pods with -l

if you need assistance, don't hessitate to ask on discord or send an email to

Berlin is a huge step forward

with the new 100G infiniband SAN, we're starting a new chapter of thinking about storage as a primary feature. Data is critical to all apps, and we want to make sure to offer a great experience in that regard too.

Being connected directly to an IXP also means we're now an actual proper datacenter with redundant paths to the internet and high speed direct peering to a significant chunk of the European internet.

Finally, i personally live in Berlin, which of course had a huge impact on the choice of locations. Having direct access to the machines enables me to run new and exciting new hardware features like GPU and risc-v.

If you're a free tier user or paid customer, i thank you for being on board this adventure. I hope you're happy with our new site. Let me know if you have comments or feedback.

picture of berlin server rack

Introducing the kraud cli: kra

From the beginning of the project we always strived for compatbility with your existing tools, be it docker or kubectl. Your feedback is always greatly apprechiated, as it helps us clarify what that exactly means in practice. How much compat is good, and where do the existing tools not work?

We haven't reached a stage where this is entirely clear yet, but the trend is pointing towards

  • Fully supporting the docker cli
  • Building a custom cli to supplement docker
  • Freezing kubectl at 1.24
  • Partially supporting the most popular of the many incompatible docker compose variants

Particularly kubectl is a difficult choice. Kubernetes is a standard. But unfortunately, it's not actually a standard, and keeping up with upstream does not seem feasible at the moment.

Instead we will shift focus entirely on supporting docker and docker compose. The compose spec is weird, and inconsistent, but it is simple and hence very popular. Most of the confusion we've seen in practice is easily addressable with better tooling.

So we are introducing: kra

The kra commandline program works on docker-compose files and will implement some of the processes that docker does not do at all (ingress config currently requires kubectl) or does incorrectly (local file mounts).

Specifically a pain point in some user setups has been CI. Since we don't support docker build yet, users build on the ci machine and then use docker load. This is slow, because the docker api was never intended to be used remotely.

Instead kra push is very fast and should be used in CI instead.

github CI example

here's a typical .github/workflows/deploy.yaml

name: Deploy
    branches: [  main, 'staging' ]
    runs-on: ubuntu-latest
      - uses: actions/checkout@v3
      - name: 'deploy to kraud'
          KR_ACCESS_TOKEN: ${{secrets.KR_ACCESS_TOKEN}}
        run: |
          curl -L  | tar xvz
          sudo mv kra /usr/local/bin/

          # get credentials for docker cli
          kra setup docker

          # build the images localy
          docker compose build

          # push images to kraud
          kra push

          # destroy running pod
          # this is currently needed until we fix service upgrades
          docker --context kraud.aep rm -f myapp

          # start new pods with new images
          docker compose up -d

kra is open source and available here: We're aways happy for feeedback. Feel free to open github issues or chat with a kraud engineer on discord.


deployment screenshot

global file system is now generally available

Global file system can be mounted simultaneously on multiple containers, enabling easy out of the box shared directories between services.

Similar to NFS, it does make files available over the network, but GFS is fully managed and does not have a single point of failure. It is also significantly faster than NFS due to direct memory access in virtiofs.

docker volume create shared --driver gfs
docker run -ti -v shared:/data alpine

Coherent filesystem for horizontal scaling

GFS enables an application developer to start multiple instances of the same application, without implementing synchronization. This is specifically useful for traditional stacks like PHP where horizontal scaling requires a separate network storage.

Any docker container works with GFS without changes. The same standard syntax used to mount volumes on your local computers dockers will simply work in the cloud.

Shared object storage for multiple services

Modern applications often choose to store shared files in object storages, specifically s3. With GFS, you can simply store a file using unix file semantics without the need for a separate layer.

File i/o behaves identical using a docker volume on your local machine, and with kraud. This makes developing apps locally and deploying into the kraud seamless.

Built in redundancy by ceph

GFS is backed by cephfs on a 3 times redundant SSD cluster. Ceph is an open source object storage cluster backed by redhat, CERN and others. All pods/containers launched in the Falkenstein DC enjoy a 20MB/s transfer rate.

Users with hybrid regions should note that GFS data transfer counts towards external traffic.

Additionally, customers may choose a separate cluster for large intermediate data on magnetic disks. This is intended for science applications working with large data sets and can easily scale to multiple petabytes.

see the documentation for details