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sys_attrs_drd(5)
NAME
  sys_attrs_drd - drd subsystem attributes

DESCRIPTION
  This reference page lists and describes attributes for the device request
  dispatcher (drd) kernel subsystem. Refer to the sys_attrs(5) reference page
  for an introduction to the topic of kernel subsystem attributes.



  Module_name
      Name of this subcomponent: DeviceIO Request Dispatcher

      Supported operations: Query



  drd_max_hash_length
      Specifies the length of the largest chain in the device request
      dispatcher subsystem's member/disk map entry hash table.

      Supported operations: Query

      Default value: 1

      Minimum value: 0

      Maximum value: 5000



  drd_hash_size
      Determines the number of hash entires allocated to keep lists of device
      request dispatcher devices.  The default is to set drd_hash_size equal
      to the largest hash list since boot.

      Supported operations: Query; Configure at boot time

      Default value: 256

      Minimum value: 1

      Maximum value: 5000



  drd_served_disks
      If this attribute is set to to 1, the device request dispatcher
      subsystem treats all disks as singly served disks, even direct-access
      I/O disks. A value of 0 (zero) enables direct-access I/O functionality.

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

      Supported operations: Query; Configure at boot time

      Default value: 0

      Minimum value: 0

      Maximum value: 1



  drd_daio_disks
      If this attribute is set to to 1, the device request dispatcher
      subsystem treats all disks as direct-access I/O disks, even single-
      server disks. A value of 0 (zero) enables single-server disks.

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

      Supported operations: Query; Configure at boot time

      Default value: 0

      Minimum value: 0

      Maximum value: 1



  drd_panic_all
      When set to 1, causes any generated panic within the device request
      dispatcher to cause all cluster node members to panic as well. This can
      be useful in determining (relative) clusterwide conditions at the time
      of a crash.

      Supported operations: Query; Configure at boot time; Reconfigure at run
      time

      Default value: 0

      Minimum value: 0

      Maximum value: 1



  drd_nolwc
      When set to 1, DRD does not use lightweight context when handling
      buffered I/O completion for disks against which I/O barriers can be
      posed.

      Supported operations: Query; Configure at boot time; Reconfigure at run
      time

      Default value: 0

      Minimum value: 0

      Maximum value: 1



  drd_remote_maxphys
      Specifies the size of the largest single I/O transfer that is supported
      when using the cluster interconnect.  I/O requests that are larger than
      this value are fragmented.

      Supported operations: Query; Configure at boot time

      Default value: 524288

      Minimum value: 262144

      Maximum value: 1048576



  drd_scan_rate
      Number of seconds between scans for restoration of failed disks.

      Setting drd_scan_rate to 0 disables scanning for restored paths. A
      single scan occurs when a device goes bad.

      Supported operations: Query; Configure at boot time

      Default value: 10

      Minimum value: 0

      Maximum value: 86400 (once per day)



  drd_iobarrier_to
      The number of seconds before timeouts on I/O barrier commands,
      including reservation and registration operations.

      If a device does not respond withing that time limit, the device will
      not be used by device request dispatcher from this member.

      The minimum is 0 (zero), which practically ensures that I/O barrier
      commands will fail, and so is of limited use.

      Supported operations: Query; Configure at boot time

      Default value: 60

      Minimum value: 0

      Maximum value: 86400



  drd_nopr_list
      First entry on the list of hardware IDs for devices on which DRD will
      not perform persistent reservations.

      Supported operations: Query; Configure at boot time; Reconfigure at run
      time

SEE ALSO
  sys_attrs(5), drdmgr(8)

Index for Section 5

Alphabetical listing for S

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