Hi all,
DB version is 11.2.0.2. Recently migraged the datafiles of db from filesystem to ASM. We faced general over all db slowness. Raised SR with Oracle initially and oracle said increase your sga to atleast thrice when moving from filesystem to ASM to compensate the loss of filesystem cache. Initial size of sga was 2gb and now increased to 10gb.
After that too the issue not resolved and avg read time of database is high 0.93ms - 14.7ms where as in filesystem it was around 0.02ms - 0.06ms.
Old server
]$ cat /proc/meminfo
MemTotal: 66567004 kB
MemFree: 45224652 kB
Buffers: 156712 kB
Cached: 18330832 kB
Here the cached is around 18gb which means actual data of the files and
SQL> show parameter filesystem
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
filesystemio_options string none
Is that when we migrate to ASM, we need take that file system cache also into consideration and set the value of sga to a higher value. Say here from original 3gb to now around ten times more than that?
baskar.l