EMC Qlogic QLA23xx Guía de instalación descargar pdf (Pagina 116)

116

EMC Fibre Channel and iSCSI with QLogic Host Bus Adapters in the Windows Environment

Troubleshooting

\\.\PHYSICALDRIVE1, and \\.\PHYSICALDRIVE2. The number

is assigned during the disk discovery part of the Windows boot

process.

During boot-up, the Windows OS loads the driver for the storage

HBAs. Once loaded, the OS performs a SCSI Inquiry command to

obtain information about all the attached storage devices. Each disk

drive it discovers is assigned a number in a semi-biased first come, first

serve fashion based on HBA. (Semi-biased means that the Windows

system always begins with the controller in the lowest-numbered PCI

slot where a storage controller resides. Once the driver for the storage

controller is loaded, the OS selects the adapter in the

lowest-numbered PCI slot to begin the drive discovery process.)

It is this naming convention and the process by which drives are

discovered that makes persistent binding (by definition) impossible

for Windows. Persistent binding requires a continuous logical route

from a storage device object in the Windows host to a volume in an

EMC storage array across the fabric. As mentioned above, each disk

drive is assigned a number in a first-come, first-serve basis. This is

where faults can occur.

Example Imagine this scenario: A host system contains controllers in slots 0, 1,

and 2. Someone removes a cable from the QLogic controller in host

PCI slot 0, then reboots the host.

During reboot, the Windows OS loads the QLogic driver during

reboot and begins disk discovery. Under the scenario presented

above, there are no devices discovered on controller 0, so the OS

moves to the controller in slot 1 and begins naming the disks it finds,

starting with \\.\PHYSICALDRIVE0. Any software applications

accessing \\.\PHSYICALDRIVE0 before the reboot will be unable

to locate their data on the device, because it changed.

The following figure shows the original configuration before the

reboot. HBA0 is in PCI slot 0 of the Windows host. Each HBA has

four disk devices connected to it, so Windows has assigned the name

\\.\PHYSICALDRIVE0 to the first disk on HBA0. Each disk after

that is assigned a number in sequence as shown in Figure 65 on

page 117.

1 2 ... 111 112 113 114 115 116 117 118 119 120 121 ... 127 128

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EMC Qlogic QLA23xx Guía de instalación Pagina 116