Solaris File SystemTuning
Thissection discusses changes that can be made for le system tuning, and includes topics that
addressthe following issues:
■“HighFile System Page-In Rate” on page 93
■“ReduceFile System Housekeeping” on page 93
■“LongService Times on Busy Disks or Volumes” on page 93
Pleaseread the descriptions of the following parameters carefully. If the description matches
yoursituation, consider making the adjustment.

High FileSystem Page-In Rate

Ifyou are seeing high le system page-in rates on Solaris 8 or 9, you might benet from
increasingthe value of segmap_percent. This parameter is set by adding the following line to
the/etc/system le:
set segmap_percent=25
segmap_percentadjusts the percentage of memory that the kernel maps into its address space
forthe le system cache. The default value is 12; that is, the kernel reserves enough space to map
atmost 12% of memory for the le system cache. On a heavily loaded machine with 4 GB of
physicalmemory, improvements have been seen with values as high as 60. You should
experimentwith this value, starting with values around 25. On systems with large amounts of
physicalmemory, you should raise this value in small increments, as it can signicantly increase
kernelmemory requirements.

ReduceFile System Housekeeping

UNIXle system (UFS) volumes maintain the time that each le was accessed. Note that the
followingchange does not turn o the access time updates when the le is modied, but only
whenthe le is accessed. If the le access time updates are not important in your environment,
youcould turn them o 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

LongS erviceTimes on Busy Disks or Volumes

WebServer's responsiveness depends greatly on the performance of the disk subsystem. Use the
iostatutility to monitor how busy the disks are and how rapidly they complete I/O requests
SolarisFileSystem Tuning
Chapter4 • Platform-Specic Issues and Tips 93