Hitachi MK-96RD647-01 manual AIX Shared Open Function, Shared Volume and FX Version

•Reserved by open-system host. When an FX volume is reserved by the open-system host, FX operations can be performed only from the host that reserved the volume. FX operations from any other open-system host will terminate unsuccessfully. Open-system reserve does not affect z/OS access to the FX volume.

•Unreserved. When an FX volume is not reserved by any z/OS or open- system host, FX operations can be performed from any open-system host using FAL/FCU. All z/OS hosts and all open-system hosts have access to unreserved volumes.

The user should implement exclusive access control and job coordination at the system level for the FX volumes. The user should also take the following steps to avoid I/O contention problems for the FX volumes:

•Open-system access. When the open-system host needs to access an FX volume, vary the volume and its channel path offline from all z/OS hosts.

•z/OS access. When the z/OS host needs to access an FX volume, stop all open-system access to the corresponding LU. For AIX, vary off the volume group(s). For Windows 2000/2003/Windows NT, use unaccess. Do not use any open-system program which accesses unmounted LUs (e.g., AIX SMIT, HP-UX SAM, and NT Disk Administrator).

AIX Shared Open Function

To share FileExchange volumes on multiple AIX operating systems:

•For FX versions 01-xx-59 and earlier, when one AIX OS opens a FileExchange volume, the other AIX OS cannot open the FileExchange volume. This is because the AIX OS reserves the FileExchange volume when it opens the it.

•For FX 01-xx-60 and later, it is possible to share an FileExchange volume across multiple AIX operating systems by specifying the environment variable:

FAL_NO_RESERVE.

The following table (Table 2-6) shows the relationship between shared volumes and FX versions.

Table 2-6 Shared Volume and FX Version

Object

Version

Description

FAL for AIX (32/64 bit)

01-xx-59 and earlier	Cannot open a shared volume from multiple AIX OSs.
01-xx-60 and later	Can open a shared volume from multiple AIX OSs by specifying the
	environment variable.

To define environment variables:

2-32 About Cross-OS File Exchange Operations

Hitachi USP V Cross-OS File Exchange User’s Guide