#Cloud File System

Overview

cfs (cloud file system) is a low-level filesystem interface for building the cloud. cfs is not a distributed file system. It is designed to be the lowest building block of cloud infrastructure that is available on all machines. The design goal of cfs is reliability, simplicity and usability.

Status

Current status is pre-alpha

TODO:

1. basic file system interface (write, read, remove, mkdir, rename)
2. copy from another cfs server
3. bit-matrix based data reconstruction
4. expose basic run time metrics
5. basic resource enforcement
6. container deployment

alpha

TODO:

1. profiling and benchmark
2. per disk metadata store
3. simple ACL support
4. user level buffer
5. tons of tests

We will BREAK everything (data format, API, command line tool, etc.) before 1.0.

Dependencies

cfs depends on GF-complete and Jerasure for erasure coding.

For now, to install these packages:

go get github.com/c-fs/gf-complete
go get github.com/c-fs/Jerasure

TODO: write build/MAKE file

Play with cfs

Run Server

cd server

go build

./server

cfs listens on 15524 by default. The root path of cfs is the current directory by default.

cfs creates a /cfs0 disk with root path /cfs0000 by default.

TODO: make all these configurable.

Run Server in a Docker Container

You can run a cfs to provide file service in container easily:

make docker

sudo docker run \
  --volume=/:/rootfs:ro \
  --volume=/var/run:/var/run:rw \
  --volume=/sys:/sys:ro \
  --volume=/var/lib/docker/:/var/lib/docker:ro \
  --volume=/tmp:/tmp:rw \
  --volume=${PWD}/cfs0000:/cfs0000
  --volume=${PWD}/cfs0001:/cfs0001
  --publish=15524:15524 \
  --detach=true \
  --name=cfs \
  c-fs/cfs

cfs is now running in the background on http://localhost:15524, and it uses ./cfs0000/ and ./cfs0001/ as data volume. For development, you can replace --detach=true with -ti to let it run as an interactive process.

Write and Read file

cd cfsctl

go build

cfsctl write --name="cfs0/foo" --data="bar"
2015/05/24 11:16:48 3 bytes written to foo at offset 0

cfsctl read --name="cfs0/foo" --length=100
2015/05/24 11:17:34 bar

Rename and Remove file

cfsctl rename --oldname="cfs0/foo" --newname="cfs0/food"
2015/05/28 15:20:22 rename cfs0/foo into cfs0/food

cfsctl remove --name="cfs0/food"
2015/05/28 15:20:43 deletion succeeded

Read a corrupted file

echo "corrupt" -> ./server/cfs0000/foo

Try to read out the file again

cfsctl read --name="cfs0/foo" --length=100
2015/05/24 11:18:56

Nothing is read out.

We can see the log output from the server side

2015/05/24 11:18:56 server: read error disk: not a valid CRC