324 Fabric OS Administrator’s Guide
53-1001763-02
Coordinated Hot Code Load
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Coordinated Hot Code Load

Coordinated Hot Code Load (HCL) removes the limitations on the number of E_Ports that can be
supported. Fabric OS v6.2.0 and later supports Coordinated HCL on all Fabric OS switches when
connected to a mixed fabric with M-EOS switches running in either McDATA Fabric or McDATA Open
Fabric mode. Coordinated HCL provides:
•Fabric-wide pause and resume
•No limitations on E_Port count or fabric membership
•Flood pause frame to all switches in the fabric before initiating a reboot
Fabric OS running on switches takes approximately 120 seconds to restart as part of the Hot Code
Activation process. During the 120 seconds when the Fabric OS switches are waiting to restart and
the switch service is not available, the M-EOS switches in the fabric may send point-to-point frames
and domain controller frames (GEPT) to the Fabric OS switches. A Fabric OS v6.3.0 switch notifies
all switches in the fabric about a pending Hot Code Activation so that they can stop sending control
frames to the specified switch until it restarts and sends a resume notification. When the switch
initiates a graceful shutdown sequence to prepare for Hot Code load, it sends a Pause notification
frame that support Coordinated HCL switches in the fabric. When the specified switch restarts it
sends out a resume notification.

Bypassing the Coordinated HCL check on firmware download

When you download the Fabric OS firmware on switches in interoperable fabrics, it automatically
starts the Coordinated HCL. The firmwareDownload command checks whether all switches in the
fabric support Coordinated HCL. If Coordinated HCL is supported, the firmwareDownload operation
proceeds and displays the normal message. If Coordinated HCL is not supported, the
firmwareDownload operation fails and prompts you to use the -o option to bypass checking the
Coordinated HCL. All domains are not capable of supporting Coordinated HCL
On switches in interop fabrics, the Coordinated HCL protocol is used to ensure data traffic is not
disrupted during firmware upgrades. Using the firmwareDownload with the -o allows the firmware
download to continue even if Coordinated HCL is not supported in the fabric or the protocol fails.
1. Enter the firmwareDownload command without any option to automatically start Coordinated
HCL.
If Coordinated HCL is not supported, the firmwareDownload operation fails and prompts you to
use the -o option to bypass checking the Coordinated HCL. All domains are not capable of
supporting Coordinated HCL.
Firmwaredownload is not running at that point.
2. Enter firmwareDownload -o to continue the download.
If Coordinated HCL is not supported in the fabric or if there is an Coordinated HCL protocol
failure to one or more of the supported switches, a best effort is made to run the Coordinated
HCL protocol. Traffic disruption can still occur for some switches in the fabric.
The normal firmwaredownload messages are displayed along with the following message:
You have elected to bypass the checking of Coordinated HCL. This may cause
traffic disruption for some switches in the fabric.
Do you want to proceed?