Note: The information contained in this article is structured as help information for the System Management Interface Tool (SMIT) and is not intended for general reading.
You can use SMIT to change configurable attributes related to asynchronous I/O. You can also configure asynchronous I/O using SMIT. To start SMIT at the main menu for Legacy Asynchronous I/O, type smit aio. To start SMIT at the main menu for Posix Asynchronous I/O, type smit posixaio.
Allows you to change the configurable attributes for asynchronous I/O.
Posix Asynchronous I/O is an asynchronous I/O that is compliant with the current Posix Standards that are supported.
Legacy Asynchronous I/O is an asynchronous I/O that has been used by the operating system in the past and which is still available in the current operating system.
To remove legacy asynchronous I/O and keep its definition, perform the following steps:
Step 1. Select "Change Show Characteristics of Asynchronous I/O".
Step 2. In the next screen, use the tab key to select "defined" in the "STATE to be configured at system restart" field, then press the Enter key.
Step 3. Reboot the machine.
To remove Posix asynchronous I/O and keep its definition, perform the following steps:
Step 1. Select "Change Show Characteristics of Posix Asynchronous I/O".
Step 2. In the next screen, use the tab key to select "defined" in the "STATE to be configured at system restart" field, then press the Enter key.
Step 3. Reboot the machine.
Enabling interrupts increases the overall load on the system. Before you choose to enable this option, you should consider whether the adapter is being used with applications or devices with special timing requirements, and which need to move small amounts of data in both directions, for example, ack and nack protocols. Interrupts should not be enabled for printers or for modems being used for file transfers. The default value is "disable".
When set to "enable", the adapter is configured to generate interrupts and the interrupt handling code is loaded and enabled. Otherwise, the existing poller code is used. The values of the attributes passed to the driver by the config method are saved by the driver.
When an 8-port PCI adapter is not configured and this value is set to "enable", adapter interrupts are disabled as part of the configuration process.
The current state of the fast path. When the fast path is enabled, the asynchronous I/O device runs with requests over a raw logical volume and avoids calls to the file system or Virtual Memory Manager (VMM). When the fast path is disabled, the asynchronous I/O passes its requests through file system code. The default value is "Enable".
If asynchronous I/O is working over a file system, the state of the fast path does not matter because it will pass its requests to file system calls that depend on VMM caching. If asynchronous I/O is using a raw logical volume with the fast path enabled, requests are sent directly to the Logical Volume Manager (LVM). File system calls are not made and requests are not passed by the Virtual Memory Manager (VMM).
If asynchronous I/O is using a raw logical volume with the fast path disabled, it treats the raw logical volume as a special file and passes its requests through the file system and VMM caching code.
The IBM 2-Port Async (PCI) Adapter supports two DB-9 connectors and programmable line speeds up to 920K baud. It can provide connectivity to asynchronous RS-232 devices such as modems and TTY terminals. Primary features of the adapter include 64-byte transmit and receive FIFOs, automatic hardware flow control, a global interrupt source register, and 16C550 compatible UART registers.
Displays a list of all IBM 2-Port Async (PCI) Adapters installed or available on this system.
Displays information about all the adapter's characteristics such as logical name, status, and location.
The logical name that is given to this adapter, for example, "sa2".
Identifies the type of adapter this is.
Identifies whether the current state of the adapter, which is "Available" (configured and ready to use) or "Defined" (known by the system, but not configured for use).
Identifies the location of the adapter and the bus that the device is attached to.