How to open asynchronous IO in HP host

First, talk about asynchronous IO (AIO) in HP-UX, when using synchronous IO, this means that the previous IO must return "Successful Write Complete" before the next write IO is performed, you can see Synchronous IO modes There is a performance bottleneck in systems that are relatively large in IO load. When using asynchronous IO methods, the operating system will immediately reflect immediately after the write request, and the remaining things are completed by the operating system. When using Oracle, Sybase in HP-UX, in order to reduce the bottleneck of IO, improve the performance of the library, it is recommended to open asynchronous IO, HP is relatively troubles with AIX in this regard.

Second, HP-UX open AIO setting 1, HP-UX uses AIO patch requirements A, HP-UX 11.00 patch requirements: phkl_22126: S700_800 VM, Async, Hyperfabric B, HP-UX 11i patch requirements To: phkl_25212 VM preemption point, mlock / ask / async_io phkl_25506 asyncio driver patch Using Swlist -l Product Checking the above patch, if there is no HP's Supporter hopped. 2. Create AIO character device A. Establish AIO character device # / sbin / mknod / dev / async C 101 0x0 b, adjust the host of the device, assuming that the user is Oracle, group is DBA #Chown Oracle: DBA / DEV / ASYNC C, adjustment device permission bit #CHMOD 660 / dev / async3, HP-UX To adjust the kernel parameters to adjust the kernel parameters to use root user A, set AsyncDSK as in Sam-> Kernel Configuration -> Drivers -> asyncdsk Adjusts to IN B, adjust the max_async_ports parameter This parameter is limited to the maximum number of processes for using / dev / async devices, and the parameters of Oracle should be greater than equal to the processes background of the Processes background in INIT . Sybase it identifies the maximum number of working processes. When the value of MAX_ASYNC_PORTS is reached, the remaining processes will use synchronous IO. C. Adjust the SET AIO_MAX_OPS parameter This parameter is defined by the maximum number of AIO operations queued at any point in time. You can keep the default value can be monitored with Glance. D, adjusting the parameter of the fs_async parameter indicates whether the write of the file system uses AIO, set fs_async = 0 Specifies that the file system does not need AIO, set fs_async = 1 specified the way AIO, Oracle is not recommended This is set to 14, and the weight of the other aspect is to set the permissions of the Mlock for the Oracle user's group (general DBA), otherwise there will be an inexplicable database when the database will be reported or in the library. HANG's phenomenon, I simply say. a, involving two commands getPrivGRP for checking groups, setPrivGRP is used to set the permissions of the group, and an example of everyone understands EG1: Check if the DBA group has mlock rights root # getprivgrp DBA EG2: Set The Mlock of the DBA group Roolt # setPrivGRP DBA Mlock B can also be added to the configuration file, so that it will automatically take effect when starting next time. The following line is added to / etc / privgroup: DBA mlock If privget does not exist, you can edit one.

Third, the database uses AIO to do set setting 1, Oracle aspect a. 7.3.0 Previous version: No need to configure the parameter b in INIT . 7.3.x: in Init . OA Setting Use_async_io = true c. 8.x and later version: Set disk_asynch_io = true2 in INIT . Ot, Sybase default is to open AIO. Fourth, other 1. Check if the AIO takes effect. #Fuser / dev / async has a process list that AIO has taken effect. 2, my HP11.00 ORACLE8.1.6.0.0 environment is enabled when AIO is enabled, and there will be a bad block problem (ORA-01578), please pay attention, but in HP11i system and Oracle8i, 9i matching did not appear This issue.