PRIMECLUSTER Global File Services Configuration and Administration Guide 4.2 (Solaris(TM) Operating Environment)

25.2 Tuning Parameters

The MDS(Meta-Data Server) of the GFS Shared File System allows tuning of 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)
• Number 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 x 1 kilobytes is reserved for the extent-based management information cache and for the directory information cache, and an area with a size equal to the specified value x 4 kilobytes is reserved for i-nodes cache. All of these areas are in the MDS process space.

By the default, two megabytes (2,048) of memory is allocated as extent management information cache, ten megabytes (10,240) of memory is allocated as directory information cache and eight megabytes (8,192) of memory is allocated as an i node cache.

If the size of a directory exceeds directory information cache size, the performance of the file creation to the directory or reference will fall. When a large directory may be created, it is strongly recommended that the amount of directory cache be set appropriately.

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

For details on sfcstat(1M), see Appendix F.2.28, "sfcstat(1M)."

(Example)

# sfcadm -o SFCFS_NCACHE_EXTENT=4096 /dev/sfdsk/gfs/rdsk/volume1
# sfcadm -o SFCFS_NCACHE_DIRECTORY=20480 /dev/sfdsk/gfs/rdsk/volume1
# sfcadm -o SFCFS_NCACHE_INODE=4096 /dev/sfdsk/gfs/rdsk/volume1