Приветствую, коллеги!
Глянул я тут давеча в zfs-stats:
root@cs0:~# zfs-stats -EZ
------------------------------------------------------------------------
ZFS Subsystem Report Sat Apr 12 16:23:52 2014
------------------------------------------------------------------------
ARC Efficiency: 175.62m
Cache Hit Ratio: 75.28% 132.20m
Cache Miss Ratio: 24.72% 43.42m
Actual Hit Ratio: 66.37% 116.56m
Data Demand Efficiency: 99.75% 67.16m
Data Prefetch Efficiency: 31.35% 62.32m
CACHE HITS BY CACHE LIST:
Anonymously Used: 9.38% 12.41m
Most Recently Used: 44.64% 59.02m
Most Frequently Used: 43.53% 57.54m
Most Recently Used Ghost: 0.06% 82.10k
Most Frequently Used Ghost: 2.38% 3.15m
CACHE HITS BY DATA TYPE:
Demand Data: 50.68% 67.00m
Prefetch Data: 14.78% 19.54m
Demand Metadata: 34.33% 45.38m
Prefetch Metadata: 0.22% 292.31k
CACHE MISSES BY DATA TYPE:
Demand Data: 0.39% 169.03k
Prefetch Data: 98.54% 42.78m
Demand Metadata: 1.03% 445.84k
Prefetch Metadata: 0.05% 19.97k
------------------------------------------------------------------------
File-Level Prefetch: (HEALTHY)
DMU Efficiency: 170.30m
Hit Ratio: 85.98% 146.42m
Miss Ratio: 14.02% 23.88m
Colinear: 23.88m
Hit Ratio: 0.02% 4.09k
Miss Ratio: 99.98% 23.87m
Stride: 103.95m
Hit Ratio: 100.00% 103.95m
Miss Ratio: 0.00% 4.21k
DMU Misc:
Reclaim: 23.87m
Successes: 1.12% 268.30k
Failures: 98.88% 23.61m
Streams: 42.48m
+Resets: 0.02% 9.57k
-Resets: 99.98% 42.47m
Bogus: 0
------------------------------------------------------------------------
root@cs0:~#
То ли я неправильно смотрю, то ли что-то неправильно показывается:
Data Prefetch Efficiency: 31.35% 62.32m
DMU Efficiency: 170.30m
Hit Ratio: 85.98% 146.42m
Miss Ratio: 14.02% 23.88m
Prefetch всё-таки эффективен или нет?
