sys_attrs_ufs(5)						File Formats Manual						  sys_attrs_ufs(5)

NAME

       sys_attrs_ufs - ufs subsystem attributes

DESCRIPTION

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

	      A value that enables (1) or disables (0) the creation of fast symbolic link files.

	      Default value: 1 (enabled)

	      Size of (number of slots in) the inode hash chain table for the inode least recently used (LRU) cache.

	      Default value: 2048 (slots)

	      Minimum value: 64

	      Maximum value:  16,384

	      Large inode hash chain tables spread the inode structures and may make chain lengths short.  This can  reduce  linear  searches  and
	      improve lookup speeds.  In general, chains should contain only 2 or 3 elements.

	      Obsolete.   This	attribute  has	been  replaced	by the vfs subsystem's max_ufs_mounts attribute, which is tunable at run time. See
	      sys_attrs_vfs(5) for information about max_ufs_mounts.

	      The range of blocks behind the current block location through which to search for a free block to allocate  for  an  indirect  block
	      write operation (for all writes other than the first). A value greater than 1 enables a look-behind search before writing each indi-
	      rect block after the first block write operation.

	      Default value: 16 (blocks)

	      Minimum value: 1

	      Maximum value: 64

	      The maximum number of vnodes that UFS can process while flushing dirty buffers on the mount list before releasing the  lock  on  the
	      mount  list  to other components.  If ufs_lockholdmax number of vnodes is reached before all dirty buffers on all vnodes are flushed
	      from the mount list, UFS releases the mount list lock and regains it later to process (flush dirty buffers on) the remaining vnodes.

	      Default value: 500 (vnodes)

	      Minimum value: 0 (means that UFS must release the mount list lock each time a vnode is processed)

	      Maximum value: 5000

	      Reducing the value of ufs_lockholdmax can improve system responsiveness for systems under heavy I/O load. The cost is an increase in
	      CPU  overhead (more time required to flush dirty buffers from the mount list). Reducing the ufs_lockholdmax value too low or on sys-
	      tems with low I/O overhead incurs CPU cost without increasing system responsiveness.

	      If the rt_preempt_opt attribute is set, ufs_lockholdmax is automatically reduced to 50  to  better  support  the	strict	preemption
	      requirements of realtime operations.

	      A  value	that  enables  (nonzero)  or  disables	(0) an operation that restricts how blocks of stale UFS data and metadata (such as
	      inodes) are reused. When ufs_object_safety is set to a nonzero value, blocks are cleared before being rewritten  and  update  opera-
	      tions  are  ordered  in  a certain way to conform to C2 security requirements. For example, during file creation, a dinode is always
	      written before a directory entry is updated to point to that dinode. When a file is deleted, the directory entry is  always  updated
	      before the dinode is deleted.

	      Default value: 0

	      Change  ufs_object_safety to a nonzero value only if a C2 security level is a system requirement. There is a serious UFS performance
	      cost associated with this change. Furthermore, the default setting, even though not in strict conformance with C2 security  require-
	      ments, leaves a low probability that confidential data will be exposed.

SEE ALSO

       sys_attrs(5)

																  sys_attrs_ufs(5)