DistributedFileSystem/ErasureCodingVSReplication.txt at master · OvroAbir/DistributedFileSystem · GitHub

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
Erasure coding scheme is better than Replication scheme overall.
Pros of Replication scheme :
- Less computation needed.
- As less computation needed, it is faster to download a file (without considering network bandwith)
Cons of Replication scheme :
- More disk space needed in chunk server side.
- Bigger network traffic between chunk servers.

Pros of Erasure coding :
- Less memory needed in Chunk server side.
Cons of Erasure Coding :
- Computationally expensive than Replication scheme.

If download frequency is laarge for a file, then it is good to follow replication scheme, as it requires less computation.
If we want to save space in Server side and download frequency is low then Erasure coding is good.

If we want to compare memory usage,
Let's say a file size is 64KB.
Replication level is 3.
For erasure coding, K = 6 and m = 3.

In case of replication scheme 64*3 = 192KB memory will be nneded in total.
In case of Erasure coding scheme (64/6)*(6+3) = 96KB memory will be needed in total.