Peter Jakab
Dabbler
- Joined
- Jun 18, 2015
- Messages
- 37
Hi All,
I am able to test MFU (Most Frequently Used) cache by simple copy same files more times. First copy from NAS slower but second works from cache. arc_summary.py show correctly how they increased as MFU:MRU ratio, global ARC cache size etc.
After I upgraded to 32GB RAM on test system and put OCZ Vertex2 60GB SSD as L2ARC cache drive (just for testing not for production - I know min. 64GB RAM needed).
I would like make load on MRU (Most Recently Used) cache in ARC and as overload could flow into L2ARC.
How I understand first file operation will load into MRU cache and response next question, but after second copy the block moved to MFU instead.
Actually my MRU cache have small ratio 6.77% after the duplicated copy operations (MFU 93.23%).
Results: Also this actually results show that not need for L2ARC for frequently re-reads due mostly ARC uses the MFU side in RAM. But before put to production I would like play with this test.
How I can make a simple traffic load to increase MFU cache and after those cache blocks goes into Ghost MRU cache (land in L2ARC) re-read to increase L2ARC hit ratio (at now 0.00% with 58 operation). And possible check difference between with and without L2ARC cache operation. I don't want install database on that.
My pool relative small so I have about 500-600GB free space to check it.
Many Thanks for ideas,
Jackson
I am able to test MFU (Most Frequently Used) cache by simple copy same files more times. First copy from NAS slower but second works from cache. arc_summary.py show correctly how they increased as MFU:MRU ratio, global ARC cache size etc.
After I upgraded to 32GB RAM on test system and put OCZ Vertex2 60GB SSD as L2ARC cache drive (just for testing not for production - I know min. 64GB RAM needed).
I would like make load on MRU (Most Recently Used) cache in ARC and as overload could flow into L2ARC.
How I understand first file operation will load into MRU cache and response next question, but after second copy the block moved to MFU instead.
Actually my MRU cache have small ratio 6.77% after the duplicated copy operations (MFU 93.23%).
Results: Also this actually results show that not need for L2ARC for frequently re-reads due mostly ARC uses the MFU side in RAM. But before put to production I would like play with this test.
How I can make a simple traffic load to increase MFU cache and after those cache blocks goes into Ghost MRU cache (land in L2ARC) re-read to increase L2ARC hit ratio (at now 0.00% with 58 operation). And possible check difference between with and without L2ARC cache operation. I don't want install database on that.
My pool relative small so I have about 500-600GB free space to check it.
Many Thanks for ideas,
Jackson