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sys_attrs_advfs(5)					   sys_attrs_advfs(5)


  sys_attrs_advfs - advfs subsystem attributes


  This reference page lists and	describes attributes for the Advanced File
  System (advfs) kernel	subsystem. Refer to the	sys_attrs(5) reference page
  for an introduction to the topic of kernel subsystem attributes.

  An asterisk (*) preceding the	name of	an attribute in	the following list
  means	that the attribute can be configured at	run time. Values of other
  attributes cannot be changed without rebooting the system.

  * AdvfsAccessMaxPercent
      The maximum percentage of	the malloc pool	(pageable memory) that can be
      possibly be allocated for	AdvFS access structures.

      Default value: 25	(percent)

      Minimum value: 5 (percent)

      Maximum value: 95	(percent)

      AdvfsAccessMaxPercent is a high-water mark of possible memory use	for
      access structures. If AdvFS cannot allocate any more access structures
      because of the memory limit imposed by AdvfsAccessMaxPercent, AdvFS
      posts an event and writes	a message in the following form	to the con-

      Could not	create new AdvFS access	structure;
      already at AdvFS memory limit as specified by
       AdvfsAccessMaxPercent value of  percent.

      At this point, the system	administrator can either kill processes	to
      cause files to be	closed or set AdvfsAccessMaxPercent to a higher



  * AdvfsDomainPanicLevel
      One of the following four	values that control what AdvFS does in the
      event of a domain	panic. The live_dump() function	mentioned in these
      descriptions is a	system call used only inside the kernel. This system
      call creates vmunix and vmcore files in the /var/adm/crash directory.
      In other words, values that enable the live_dump() call allow the
      creation of dump files without calling panic() to	crash the system.

      0	      Do not call live_dump() for a domain panic in either an
	      unmounted	or mounted domain.

      1	(the default)
	      Call live_dump() only if the domain panic	occurred in a domain
	      that is mounted.

      2	      Call live_dump() if a domain panic occurred in either a mounted
	      or unmounted domain.

      3	      Promote the domain panic to a system panic.  This	causes the
	      system to	crash, which yields a crash dump when the system is

  * AdvfsFavorBlockingQueue
      The value	that controls the priority for moving synchronous  or asyn-
      chronous I/O requests from the consolidation queue to the	device queue.
      When the value is	1, AdvFS first flushes synchronous I/O to disk.	 When
      the value	is 0 (zero), asynchronous I/O is flushed to disk, regardless
      of synchronous I/O.

      Default value: 1

      Do not modify the	default	setting	for this attribute unless instructed
      to do so by support personnel or by patch	kit documentation.

  * AdvfsMaxDevQLen
      The highest number of I/O	requests that can be on	the AdvFS device
      queue before that	queue is limited to synchronous	requests. The AdvFS
      device queue accepts both	asynchronous I/O requests and synchronous I/O
      requests.	 When the number of requests on	the device queue exceeds the
      value of this attribute, only synchronous	requests are accepted onto
      the queue.

      Default value: 24	(requests)

      Minimum value: 0 (requests)

      Maximum value: 65536 (requests)

      The default value	should be appropriate for most configurations.	How-
      ever, you	may need to modify the default value for systems with very
      fast or very slow	devices	and adapters.  One guideline is	to specify a
      value for	the AdvfsMaxDevQLen attribute that is less than	or equal to
      the average number of I/O	operations that	can be performed in 0.5
      seconds.	If you do not want to limit the	size of	the device queue, set
      the value	of the AdvfsMaxDevQLen parameter to 0 (zero).

  * AdvfsMaxFragGrps
      The threshold number of fragment groups on the free list that starts
      fragment group deallocation from the list. Deallocation starts when the
      number of	fragment groups	on the free list is higher than	this value.

      Default value: 48	(groups)

      Minimum value: 4 (groups)

      Maximum value: 8,388,608 (groups)

  * AdvfsMaxFreeAccessPercent

  * AdvfsMinFragGrps
      The threshold number of fragment groups on the free list that stops
      fragment group deallocation from the list. Deallocation stops when the
      number of	fragment groups	on the free list is less than this value.

      Default value: 16	(groups)

      Minimum value: 3 (groups)

      Maximum value: 8,388,607 (groups)

  * AdvfsMinFreeAccess

  * AdvfsReadyQLim
      The number of 512-byte blocks that can be	on the readylazy queue before
      AdvFS starts moving I/O requests to the device queue.

      Default value: 16	K (blocks)

      Minimum value: 0,	which disables buffering on the	readylazy queue

      Maximum value: 32	K (blocks)

  * AdvfsSyncMmapPages
      A	value that controls whether modified (dirty) mmapped pages are
      flushed to disk during a sync() system call.  If the value is 1, the
      dirty mmapped pages are asynchronously written to	disk.  If the value
      is 0 (zero), dirty mmapped pages are not written to disk during a	sync
      system call.

      Default value: 1



  AdvFS	Administration

  System Configuration and Tuning