2장. 멀티패스 장치
Without DM Multipath, each path from a server node to a storage controller is treated by the system as a separate device, even when the I/O path connects the same server node to the same storage controller. DM Multipath provides a way of organizing the I/O paths logically, by creating a single multipath device on top of the underlying devices.
2.1. 멀티패스 장치 식별자
각각의 멀티패스 장치에는 WWID (World Wide Identifier)가 있어, 고유하게 구별되고 변경되지 않게 합니다. 기본값으로 멀티패스 장치 이름은 해당 WWID로 설정됩니다. 다른 방법으로, 멀티패스 설정 파일에서
mpathn 형식의 고유한 노드명으로 별칭을 설정하는 user_friendly_names 옵션을 설정할 수 있습니다.
For example, a node with two HBAs attached to a storage controller with two ports by means of a single unzoned FC switch sees four devices:
/dev/sda, /dev/sdb, dev/sdc, and /dev/sdd. DM Multipath creates a single device with a unique WWID that reroutes I/O to those four underlying devices according to the multipath configuration. When the user_friendly_names configuration option is set to yes, the name of the multipath device is set to mpathn.
When new devices are brought under the control of DM Multipath, the new devices may be seen in two different places under the
/dev directory: /dev/mapper/mpathn and /dev/dm-n.
/dev/mapper에 있는 장치는 이전의 부팅 프로세스에서 생성된 것입니다. 논리 볼륨을 생성할 때와 같이 멀티패스된 장치를 액세스하기 위해 이 장치를 사용합니다.- Any devices of the form
/dev/dm-nare for internal use only should never be used by the administrator directly.
For information on the multipath configuration defaults, including the
user_friendly_names configuration option, see 4.3절. “설정 파일 기본값 ”.
You can also set the name of a multipath device to a name of your choosing by using the
alias option in the multipaths section of the multipath configuration file. For information on the multipaths section of the multipath configuration file, see 4.4절. “멀티패스 장치 설정 속성 ”.
