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Some question about SAN on HP 4400 EVA
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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)
