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Solaris File System Tuning
This section discusses changes that can be made for file system tuning, and includes topics that
address the following issues:
■
“High File System Page-In Rate” on page 93
■
“Reduce File System Housekeeping” on page 93
■
“Long Service Times on Busy Disks or Volumes” on page 93
Please read the descriptions of the following parameters carefully. If the description matches
your situation, consider making the adjustment.
High File System Page-In Rate
If you are seeing high file system page-in rates on Solaris 8 or 9, you might benefit from
increasing the value of
segmap_percent
. This parameter is set by adding the following line to
the
/etc/system
file:
set segmap_percent=25
segmap_percent
adjusts the percentage of memory that the kernel maps into its address space
for the file system cache. The default value is 12; that is, the kernel reserves enough space to map
at most 12% of memory for the file system cache. On a heavily loaded machine with 4 GB of
physical memory, improvements have been seen with values as high as 60. You should
experiment with this value, starting with values around 25. On systems with large amounts of
physical memory, you should raise this value in small increments, as it can significantly increase
kernel memory requirements.
Reduce File System Housekeeping
UNIX file system (UFS) volumes maintain the time that each file was accessed. Note that the
following change does not turn off the access time updates when the file is modified, but only
when the file is accessed. If the file access time updates are not important in your environment,
you could turn them off by adding the
noatime
parameter to the data volume's mount point in
/etc/vfstab
. For example:
/dev/dsk/c0t5d0s6 /dev/rdsk/c0t5d0s6 /data0 ufs 1 yes noatime
Long Service Times on Busy Disks or Volumes
Web Server's responsiveness depends greatly on the performance of the disk subsystem. Use the
iostat
utility to monitor how busy the disks are and how rapidly they complete I/O requests
Solaris File System Tuning
Chapter 4 • Platform-Specific Issues and Tips 93