fcache_seqlimit_scope man page on HP-UX

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fcache_seqlimit_scope(5)			      fcache_seqlimit_scope(5)

NAME
       fcache_seqlimit_scope  -	 sequential  access detection control for file
       cache

VALUES
   Failsafe
   Default
   Allowed values
       The minimum value allowed is
       The maximum value allowed is

DESCRIPTION
       This parameter controls sequential access detection for different types
       of sequential accesses.

       It  is  important to note the relationship between this tunable and and
       These two tunables must be set to a value other than the	 default  val‐
       ues.   If not, setting the tunable will not have any effect on the sys‐
       tem.  See  fcache_seqlimit_file(5)  and	fcache_seqlimit_system(5)  for
       more information.

       Customers  must consider the file system sequential operations in their
       workload environment before changing the value of this tunable from the
       default	value  on  production  systems.	  It  is  specifically used to
       improving sequential I/O	 performance  for  large  files.   Setting  an
       improper	 value	may  cause  system  performance	 degradation.  In most
       cases, the default value should be sufficient.

       This tunable has four settings:

	      This is the default setting.  It corresponds to the HP-UX 11i v3
		     default behavior.	Allows detection of all the sequential
		     accesses.

	      This setting allows detection of all the sequential reads.
		     It	 is  appropriate  to  set this value if file system is
		     doing more sequential reads to a large file than writes.

	      This setting allows detection of all the sequential writes.

	      This setting allows detection of sequential append only writes.

   Who is Expected to Change This Tunable?
       System administrators that run applications which do  large  sequential
       file  I/O's.   Typically,  these	 files are larger than the size of the
       file cache on the system.

   Restrictions on Changing
       Changes to this tunable take effect immediately.

   When Should the Value of This Tunable Be Changed to 1?
       This tunable should be changed from 0 to 1 if applications are expected
       to do more sequential reads than writes.

   When Should the Value of This Tunable Be Changed to 2?
       This  tunable should be changed to 2 if applications are expected to do
       more sequential writes to a large file than reads.

   When Should the Value of This Tunable Be Changed to 3?
       This tunable should be changed to 3 if applications are expected to  do
       more sequential append only writes than sequential reads and non-append
       writes.

   What Are the Side Effects of Changing the Value?
       Setting the tunable other than the default value may  cause  more  page
       outs.   Setting the tunable to an improper value may yield poor perfor‐
       mance for large sequential I/O's on large files (larger	than  physical
       memory  size).	For example if an application is doing more sequential
       writes than reads, setting the tunable to a value  other	 than  2  will
       cause system performance degradation.

       The  tunable  should  be exercised with extreme caution as it will have
       impact on file system throughput.

   What Other Tunable Values Should Be Changed at the Same Time?
       and should be changed to other than the default value.

WARNINGS
       All HP-UX kernel tunable parameters are release specific.  This parame‐
       ter  may	 be  removed or have its meaning changed in future releases of
       HP-UX.

       Installation of optional kernel software, from HP or other vendors, may
       cause  changes  to  tunable parameter values.  After installation, some
       tunable parameters may no longer be at the default or recommended  val‐
       ues.  For information about the effects of installation on tunable val‐
       ues, consult the documentation for the kernel software being installed.
       For  information	 about	optional  kernel  software  that  was  factory
       installed on your system, see at

AUTHOR
       was developed by HP.

SEE ALSO
       fcache_seqlimit_file(5), fcache_seqlimit_system(5).

			   Tunable Kernel Parameters  fcache_seqlimit_scope(5)
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