说的比较直白，不做翻译，直接贴
APPLIES TO:
Oracle Database - Enterprise Edition - Version 11.2.0.1 to 12.1.0.2 [Release 11.2 to 12.1]
Information in this document applies to any platform.
SYMPTOMS
1) Monitoring a 20TB ACFS filesystem (using "df -i" command) alerted that very few files are using many inodes.
2) Per 'df -i' command, e.g. Inodes is = 41943040000, IUsed is = 419430400, and IFree is = 41523609600:
[root@dbaasm ~]# df -i /u04acfs
Filesystem Inodes IUsed IFree IUse% Mounted on
/dev/asm/ebernal-225 41943040000 419430400 41523609600 1% /u04acfs
3) Whereas "df -m" command shows the space allocation in MB:
[root@dbaasm ~]# df -m /u04acfs
Filesystem 1M-blocks Used Available Use% Mounted on
/dev/asm/ebernal-225 20971520 209715 20761805 1% /u04acfs
4) Per 'ls -lR | wc -l' lists just 246 files.
5) It was unclear why 246 files + small number of directories is using 419,430,400 Inodes.
6) Can anything be done to increase # of inodes in ACFS filesystems?
CAUSE
a) ACFS filesystems does not use the inode architecture.
b) ACFS filesystems does not have a pre-allocated inode table.
SOLUTION
1) Therefore, "df -i" command returns the number of inodes that are theoretically possible given the space remaining.
2) On ACFS filesystems, the inode table grows dynamically. Any free storage is eligible for inode creation.
3) Thus, "df -m" command (with the "-m" option or equivalent) needs to be used instead to report the real ACFS filesystem allocation and available free space, as follows:
[root@dbaasm ~]# df -m /u04acfs
Filesystem 1M-blocks Used Available Use% Mounted on
/dev/asm/ebernal-225 20971520 209715 20761805 1% /u04acfs
