New XD modes, N+M code for advance disk and node protection
The new XD Mode raises the disk and node redundancy when adding new storage nodes to the SCALA system. You can start with only two storage nodes with disk protection only and upgrade to node protection at a later time. The new SCALA XD mode will dynamically change the algorithms for disk protection and node protection once the minimum requirement is met.
XD mode supports N+M protection schemes, where M is number of disk storing data, and N the allowable number of failures. You data is spread across (N) from 2, 4, 8, 16, while allowable disk failures(M) from 1 to 4 disks. There are total of 14 combination of N+M, and provides the user the flexibility of various degrees of performance and capacity utilization.
XD mode supports N+M protection schemes, where M is number of disk storing data, and N the allowable number of failures. You data is spread across (N) from 2, 4, 8, 16, while allowable disk failures(M) from 1 to 4 disks. There are total of 14 combination of N+M, and provides the user the flexibility of various degrees of performance and capacity utilization.
XD Protection Mode (min. 2 nodes) |
Number of Disk Span (N) |
Disk Failure Allowed (M) |
Min. Node to Allow Node Failure |
Node Failure Allowed |
2+1 |
2 |
1 |
3 |
1 |
2+2 |
2 |
2 |
4 |
2 |
4+1 |
4 |
1 |
5 |
1 |
4+2 |
4 |
2 |
6 |
2 |
4+3 |
4 |
3 |
7 |
3 |
4+4 |
4 |
4 |
8 |
4 |
8+1 |
8 |
1 |
9 |
1 |
8+2 |
8 |
2 |
10 |
2 |
8+3 |
8 |
3 |
11 |
3 |
8+4 |
8 |
4 |
12 |
4 |
16+1 |
16 |
1 |
17 |
1 |
16+2 |
16 |
2 |
18 |
2 |
16+3 |
16 |
3 |
19 |
3 |
16+4 |
16 |
4 |
20 |
4 |
Over 90% Storage Utilization Starting with 2 nodes
New XD mode allows multiple N+M protection mode even with only 2 nodes. It allows up to more than 90% disk utilization to balance performance and protection. XD Mode is a flexible setting that can be changed at anytime to fit your current application or user needs.
XD Protection Mode (min. 2 nodes) |
Storage Utilization |
Performance |
Redundancy |
2+1 |
66% |
Higher |
Balanced |
2+2 |
50% |
Balanced |
Higher |
4+1 |
80% |
Highest |
Balanced |
4+2 |
66% |
Higher |
High |
4+3 |
57% |
High |
Higher |
4+4 |
80% |
Balanced |
Highest |
8+1 |
88% |
Highest |
Balanced |
8+2 |
80% |
Higher |
High |
8+3 |
72% |
High |
Higher |
8+4 |
66% |
Balanced |
Highest |
16+1 |
94% |
Highest |
Balanced |
16+2 |
88% |
Higher |
High |
16+3 |
84% |
High |
Higher |
16+4 |
80% |
Balanced |
Highest |