EMC P/N 300-002-803 manual Device reconfiguration Device numbering

Additional Notes

Device reconfiguration: Device numbering

In the Linux kernel, the SCSI addresses are not used in the device names as they are in other types of UNIX (Sun, SGI, HP-UX, and BSD, for example). Block device filenames take the form /dev/sd ln, where l is the letter denoting the physical drive and n is the number denoting the partition on that physical drive. Disk device file names and major and minor numbers are assigned dynamically at boot time or device loading time in the order of discovery.

Depending upon the hardware configuration, if a device is added and the system rebooted, the device numbering might change, possibly rendering the host's mount table inaccurate. For the most consistent results and to reduce the possibility of mount table inaccuracies, new devices should be appended (if possible) to the list of already attached devices. For example, if the host contains multiple adapters, it would be best to append the new device to the last adapter and to the end of the device list attached to that adapter. This would eliminate the need to alter the preexisting entries in the mount table, since the new device could be appended to that as well.

If a new device were added to the first out of two adapters and the system rebooted, the devices all shift by one number and the mount table entries would also need to be shifted by one device. If there is only one adapter, the new device can more easily be appended to the list of the regularly attached devices and the mount table altered accordingly.

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EMC Host Connectivity with QLogic FC and iSCSI HBAs and FCoE CNAs for the Linux Environment