PRIMECLUSTER Global File Services Configuration and Administration Guide 4.1 (Solaris(TM) 10 Operating System)

14.1.1 Amount of Cache

It is possible to tune the following items:

• Amount of extent-based management information to be cached in memory
  (SFCFS_NCACHE_EXTENT)
• Amount of directory information to be cached in memory
  (SFCFS_NCACHE_DIRECTORY)
• Amount of i-nodes on the disk to be cached in memory
  (SFCFS_NCACHE_INODE)

These values can be specified using sfcadm(1M).

For each file system, an area with a size equal to the specified value multiplied by 1 kilobyte is reserved for the extent-based management information and for the directory information, and an area with a size equal to the specified value multiplied by 4 kilobytes is reserved for i-nodes. All of these areas are in the MDS process space.

By default, 2 megabytes (2048) of memory is used for caching extent management information, 10 megabytes (10240) of memory is used for caching directory information, and 8 megabytes (8192) of memory is used for caching i-node information.

If the size of a directory exceeds the directory cache's size, performance of file creation in the directory or reference will fall. When a large directory is created, we recommend strongly that users increase the size of the directory information cache significantly.

Use sfcstat(1M), the statistics command specific to the GFS Shared File System, to determine the cache hit ratios for the items above and perform tuning if necessary.

(Example)

# sfcadm -o SFCFS_NCACHE_EXTENT=4096 /dev/sfdsk/gfs01/rdsk/volume01 <Enter>
# sfcadm -o SFCFS_NCACHE_DIRECTORY=20480 /dev/sfdsk/gfs01/rdsk/volume01 <Enter>
# sfcadm -o SFCFS_NCACHE_INODE=5120 /dev/sfdsk/gfs01/rdsk/volume01 <Enter>