Overview

This repository is created for "Optimal Data Placement for Stripe Merging in Locally Repairable Codes", including the system implementation(stripe-merging/ms_code/ directory). Our contribution is to propose merging-style redundancy transitions for LRC(Locally-Repairable-Codes) and PC(Product Codes). We Design novel stripe data placement schemes that achieve excellent transition performance for modern data centers. We find that merging-style transition is better than existed approaches in terms of the transition performance.

For LRC: Overall,our stripe-merging transition consists of two parts:Coding technique and Pre-designed Placement,they play a major role for different redundancy requirements.Specifically, We are interested in two special case:1)x (k-l-g) lrc stripes merging to a (x * k,x * l,g) lrc stripe.2)x (k-l-g) stripes merging to a (x * k,x * l,x * g) lrc stripe.Also,since cross cluster traffic proves to be dominant,we use cross cluster traffic blocks as transition performance metric.For more details,We recommend referring to our paper.

For PC: Overall,our stripe-merging transition consists of two parts:Coding technique and Pre-designed Placement,they play a major role for different redundancy requirements.Specifically, We are interested in two special case:1)x (h,v) pc stripes merging to a (xh,v) pc stripe.2)x (h,v) stripes merging to a (h,xv) pc stripe.

Simulation

We perform simulations to show advantages of our design and explore how much can we gain with different configurations.We consider different $x$ and different parameters $(h,v)$. We set the number of stripes as 100, and the number of clusters (i.e., $c$) as $xv+1$, i.e., the number of clusters the DIS placement spans. We calculate the average transitioning cost for merging every $x$ small-size stripes.

System Implementation

We implement an erasure coding tiny dfs of about 4000 sloc as testbed and further perform system evalution on it.The architecture follows master-worker style,like many state-of-art distributed file storage suchas HDFS,Ceph.Three major components are client,coordinator,datanode.

Currently,we do not care availabilty issue and just deploy single coordinator,we encourage anyone to perfect the system,for example,you can bring it more availability by adding more CNs and keep them in consistent state by consensus protocol like raft or existed coordinate service like Zookeeper.

Transition process logically looks similar like this.Briefly Speaking,the client sends a rpc to CN which tells CN to start transition.Then,CN generates a transition plan and guides picked DNs to transfer data blocks or complete coding task parallelly.DN actually perform overall blocks sending and receiving.Once DNs complete the task,they send an ack back to CN,so that CN can further modify corresponding meta data and return transition statistics(we use transition duration) to client.We currently focus on two special cases:x=1(g same) and x=2(g double) in experiments.

For PC,We assume the following default configurations. We adopt the transitioning parameters $x = 2$ PC(2, 4). We set the block size as 64,MB, and the packet size for network transfer as 1,MB. We upload 100,stripes of data and parity blocks, so the total data volume is around 90,GB. We set the number of clusters as 9. We vary different parameters in our experiments. We measure the time for transitioning all stripes.

User is required to input coding parameter,block size,stripe number and placement policy when start a client to upload stripes.When transition,it asks for transition policy and transition cases(i.e. g same or g double),and finally gets transition duration as result from CN.

Note:We use a physical node to simulate a cluster in productive environment.Similarly,cross cluster bandwidth and inner cluster bandwidth correspond to cross node bandwidth(we deploy system in a LAN) and disk io(SSD in our experiments).

How to install protobuf

git clone -b 3.10.x https://github.com/protocolbuffers/protobuf.git
cd protobuf
git submodule update --init --recursive
./autogen.sh
cd cmake
mkdir build
cd build/
cmake -G Ninja -DCMAKE_INSTALL_PREFIX=/home/ms/Documents/peper2022/protobuf -DCMAKE_POSITION_INDEPENDENT_CODE=ON -DCMAKE_BUILD_TYPE=Release -Dprotobuf_BUILD_TESTS=OFF ..
ninja
sudo ninja install
sudo apt install ninja-build 

How to install grpc

git clone https://gitee.com/duduqp/dudugrpc.git
cd grpc
git submodule update --init
mkdir -p cmake/build
cd cmake/build

#set(CMAKE_INSTALL_PREFIX "/home/ms/Documents/peper2022/grpc")

cmake \
  -DCMAKE_BUILD_TYPE=Release \
  -DgRPC_INSTALL=ON \
  -DgRPC_BUILD_TESTS=OFF \
  -DgRPC_SSL_PROVIDER=package \
  ../..

make install -j8 DESTDIR=/home/ms/Documents/peper2022/grpc