Dynamically changing channel paths

To dynamically change a channel path, use the following general steps:

1. For channel paths that you plan to change, if you are changing certain fields in the IODF, you must configure channel paths offline.

   To guard against losing I/O access unexpectedly, you must vary offline I/O devices before you activate an IODF that changes the characteristic fields described in Table 1:

   Table 1. Dynamic I/O Offline Requirements for Channel Path Fields

   Vary the affected components offline before activating a new IODF that changes these channel path characteristics:	Before activating the new IODF, take the following actions:
   Channel Path Type Dynamic Switch ID Operation Mode	In all logical partitions in your processor complex, configure the channel path offline. If the channel path is the last path to an I/O device, you must vary the device offline before you can configure the channel path offline.
   Channel Path Access List Channel Path Candidate List	In each logical partition that will lose access to I/O devices on this channel path, do the following: For I/O devices that will become inaccessible to the logical partition, vary those I/O devices offline. For I/O devices that will remain accessible by the logical partition through other channel paths, vary offline only the logical paths associated with this channel path. Configure the channel path offline. Note: For coupling facility sender channel paths, you must first vary the CF sender channel path offline to the coupling facility. In all logical partitions that will gain access or continue accessing this channel path, you need not configure or vary anything offline.

   Note: This table is also valid for spanned channels.
   You do not, however, have to vary an I/O device offline before activating an IODF when you change any of the following I/O device characteristics:

   • Entry Switch Number
   • Entry Port
   • Description
2. Describe the new I/O configuration definition in an I/O definition file (IODF) that you create through HCD.
3. Activate the new IODF.
   Note: You usually cannot remove a logical partition from a channel path candidate list unless the channel path is offline. You can, however, remove a logical partition, other than your own, from the channel path candidate list for a reconfigurable or shared ESCON® connection (CNC and CTC) or coupling facility sender channel path while the channel path is online to the other logical partition if you perform one of the following actions:
   • Use the ACTIVATE command with the FORCE(CANDIDATE) parameter.
   • On the HCD Activate New Hardware and Software Configuration panel, specify "Yes" in the "Delete partition access to CHPIDs unconditionally (FORCE=CANDIDATE)" field.