Name: aliyesami Date: June 2, 2008 at 13:38:01 Pacific Subject: question about performance OS: 7.3-2 CPU/Ram: 8/48GB Model/Manufacturer: AXP
Comment:
hi ! below is the output of 'show memory' command on my system. how can I interpret this output ? The extended cache size free is zero does it mean we should increase it?
Physical Memory Usage (pages): Total Free In Use Modified Main Memory (48.00GB) 6291456 1546060 4715267 30129
Extended File Cache (Time of last reset: 1-JUN-2008 21:58:58.83) Allocated (GBytes) 5.58 Maximum size (GBytes) 24.00 Free (GBytes) 0.00 Minimum size (GBytes) 0.00 In use (GBytes) 5.57 Percentage Read I/Os 42% Read hit rate 96% Write hit rate 0% Read I/O count 13757749 Write I/O count 18873801 Read hit count 13325629 Write hit count 0 Reads bypassing cache 244 Writes bypassing cache 15783149 Files cached open 1352 Files cached closed 14830 Vols in Full XFC mode 0 Vols in VIOC Compatible mode 19 Vols in No Caching mode 28 Vols in Perm. No Caching mode 0
No worry (I even don't know in which situation the allocated cache is not used, i.e. free). The used only 5.58 of the possible 24 Gb of cache (the default, half of the physical memory). Your system seems to be domintated by disk writes, almost all reads (96%) are served from cache. What I am wondering a bit are the 28 volumes in no caching mode: are they explicitly mounted with /NOCACHE ?
yes I checked and the volumes are mounted with NOCACHE . are the cache for disks normally enabled? what are the advantanges n disadvantages of doing this?
As in Your subject "... performance". In Your case, You have still alot free memory for caching. Caching impoves performance for files which are read rather frequently, such as the system disk or sources repositories in development environments.
