*nix Documentation Project
·  Home
 +   man pages
·  Linux HOWTOs
·  FreeBSD Tips
·  *niX Forums

  man pages->Tru64 Unix man pages -> sys_attrs_ufs (5)              



NAME    [Toc]    [Back]

       sys_attrs_ufs - ufs subsystem attributes

DESCRIPTION    [Toc]    [Back]

       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)

              A value that enables (1) or disables (0) the delaying
 of full write buffer flushing to  disk  at  the
              next  sync  call.  Enabling  this  attribute  might
              adversely affect real-time workload performance.

              Default value: 0 (disabled)

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

              Default value: 2048 (slots)

              Minimum value: 64

              Maximum value:  1,073,741,824

              Large inode hash  chain  tables  spread  the  inode
              structures  and  may  make  chain lengths short. In
              general, chains should contain only  2  or  3  elements.
  This can reduce linear searches and improve
              lookup speeds. Therefore, ncreasing  the  value  of
              inode_hash_size   can   improve   performance   but
              requires more memory; values closer to the  maximum
              are  recommended  only  for Very Large Memory (VLM)

              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  This attribute has been replaced by  the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 indirect block after  the  first  block  write

              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

              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 systems 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

              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 operations
 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 (disabled)

              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
              requirements, leaves a low probability that  confidential
 data will be exposed.

SEE ALSO    [Toc]    [Back]


[ Back ]
 Similar pages
Name OS Title
sys_attrs_bcm Tru64 bcm subsystem attributes
sys_attrs_lag Tru64 lag subsystem attributes
sys_attrs_isp Tru64 isp subsystem attributes
sys_attrs_xpr Tru64 xpr subsystem attributes
sys_attrs_dli Tru64 dli subsystem attributes
sys_attrs_sec Tru64 sec subsystem attributes
sys_attrs_lta Tru64 lta subsystem attributes
sys_attrs_ee Tru64 ee subsystem attributes
sys_attrs_net Tru64 net subsystem attributes
sys_attrs_i2o Tru64 i2o subsystem attributes
Copyright © 2004-2005 DeniX Solutions SRL
newsletter delivery service