MG-K: Raid and ext2

ext2's design means it reads a lot of it's data from the beginning of blocks, when you put ext2 on top of raid, it's possible to create a situation where the beginning of blocks all end on the same disk, creating a performance bottleneck.

Block: 4K Group: 32K Chunk 4K Disks: 4 Bad


Disk1 – Chunk: 4K

Disk2 – Chunk: 4K

Disk3 – Chunk: 4K

Disk4 - Chunk: 4K

E2fs data

Block 1.1 – 4K

Block 1.2 - 8K

Block 1.3 - 12K

Block 1.4 - 16K

E2fs data

Block 1.5 - 20K

Block 1.6 – 24K

Block 1.7 – 28K

Block 1.8 - 32K

E2fs data

Block 2.1 – 4K

Block 2.2 – 8K

Block 2.3 – 12K

Block 2.4 - 16K



Block: 4K Group: 32K Chunk 4K Disks: 3 Good


Disk1 – Chunk: 4K

Disk2 – Chunk: 4K

Disk3 – Chunk: 4K

E2fs data

Block 1.1 – 4K

Block 1.2 - 8K

Block 1.3 - 12K

E2fs data

Block 1.4 - 16K

Block 1.5 - 20K

Block 1.6 – 24K

E2fs data

Block 1.7 – 28K

Block 1.8 - 32K

Block 2.1 – 4K

E2fs data

Block 2.2 – 8K

Block 2.3 – 12K

Block 2.4 - 16K



Block: 1K Group: 8K Chunk: 8K Disks: 4 Good


Disk1 – Chunk: 8K

Disk2 – Chunk: 8K

Disk3 – Chunk: 8K

Disk4 - Chunk: 8K

E2fs data

Group 1.1 - 8K

Group 2.1

Group 3.1

Group 4.1



Block: 4K Group: 32K Chunk: 32K Disks: 4 Good


Disk1 - Chunk: 32K

Disk2 - Chunk: 32K

Disk3 - Chunk: 32K

Disk4 - Chunk: 32K

E2fs data

Group 1.1 - 32K

Group 2.1

Group 3.1

Group 4.1



Block: 4K Group: 32K Chunk: 64K Disks: 4 Good


Disk1 - Chunk: 64K

Disk2 - Chunk: 64K

Disk3 - Chunk: 64K

Disk4 - Chunk: 64K

E2fs data

Group 1.1 – 32K

Group 3.1

Group 5.1

Group 7.1

E2fs data

Group 2.1 - 64K

Group 4.1

Group 6.1

Group 8.1



Block: 1K Group: 8K Chunk: 32K Disks: 4 Good


Disk1 – Chunk: 32K

Disk2 – Chunk: 32K

Disk3 – Chunk: 32K

Disk4 – Chunk: 32K

E2fs data

Block 1.1 - 8K

Block 5.1

Block 9.1

Block 13.1

E2fs data

Block 2.1 - 16K

Block 6.1

Block 10.1

Block 14.1

E2fs data

Block 3.1 - 24K

Block 7.1

Block 11.1

Block 15.1

E2fs data

Block 4.1 - 32K

Block 8.1

Block 12.1

Block 16.1



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