st_ats_enable(5)						File Formats Manual						  st_ats_enable(5)

NAME

       st_ats_enable - determine whether to reserve a tape device on open

VALUES

   Default
   Allowed values
   Recommended values
DESCRIPTION

       Note: this tunable was named in releases prior to HP-UX 11i v3.

       This  tunable  notifies	the stape or estape driver whether it needs to reserve a tape device on open and subsequently release it on close.
       When this tunable is on, the stape or estape driver will attempt to reserve any tape device on open.  The driver has  a	few  tape  devices
       flagged	as  suitable  devices  for this functionality including: DLT 8000, DLT 7000, STK 9840, HP Ultrium, and others.	DDS drives are not
       flagged for this functionality.

       The tunable allows the safe sharing of tape devices in multinode configurations like MC/ServiceGuard's Advanced Tape  Sharing.	The  auto-
       matic  reserve  and release protects the tape device from being accessed from multiple nodes, which would corrupt a backup.  If the reserve
       portion of the stape or estape driver's open routine fails, a status of is returned.

   Who Is Expected to Change This Tunable?
       Anyone.

   Restrictions on Changing
       Changes to this tunable take effect immediately and are used during the next open or close.

   When Should the Tunable Be Turned On?
       This tunable should be turned on if the system is going to be used in an MC/ServiceGuard's Advanced Tape Sharing configuration or the  user
       wants the stape or estape driver to use automatic reserve and release on open and close for multinode manageability.

   What Are the Side Effects of Turning the Tunable On?
       A  reserve is sent to the tape device by the stape or estape driver on open and a release is sent on close.  No other initiator or HBA will
       be able to access the tape device while it is opened on another initiator or HBA.

   When Should the Tunable Be Turned Off?
       This tunable should be turned off for any SAN tape sharing solution configuration other than ATS.  Most multinode backup applications  (for
       example,  Omniback)  manage  device  reservation themselves, and any interference by the stape or estape driver may produce problems.  This
       tunable should also be turned off for any multiplatform SAN configuration to keep tape access across platforms more uniform.

   What Are the Side Effects of Turning the Tunable Off?
       Unauthorized access from another initiator might interfere with any current tape operation.

   What Other Tunables Should Be Changed at the Same Time?
       None.

EXAMPLES

       Query the current value of the tunable:

       Set the value of the tunable to

       To save the value of the tunable across reboots:

WARNINGS

       All HP-UX kernel tunable parameters are release specific.  This parameter 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 values.  For information about the effects of installation  on  tun-
       able  values,  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

       scsi_tape(7), scsimgr_estape(7).

							     Tunable Kernel Parameters						  st_ats_enable(5)