Linux device-mapper (multipath) (dm)

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Linux device-mapper (multipath) (dm)

sources:

Chapter 1. Device Mapper Multipathing

https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/6/html/DM_Multipath/MPIO_Overview.html

http://n4f.siftusystems.com/index.php/2013/07/03/iscsi-multipathing-mpio/

Device mapper multipathing (DM-Multipath) allows you to configure multiple I/O paths between server nodes and storage arrays into a single device. These I/O paths are physical SAN connections that can include separate cables, switches, and controllers. Multipathing aggregates the I/O paths, creating a new device that consists of the aggregated paths.

iSCSI multipathing - MPIO

- Posted by siftu, 2013-07-03

Networking, NAS4Free

source: http://n4f.siftusystems.com/index.php/2013/07/03/iscsi-multipathing-mpio/

Overview

I’m going to go through the steps of creating a multipath iSCSI connection with NAS4Free. In this configuration it is possible to use multiple NICs to exceed bandwidth of a single NIC for a single TCP session. It is a common misconception that this is also possible with LACP; it is not. No matter how many links you have in a LACP aggregate it is not possible to exceed the bandwidth of a single link for a single TCP session/transfer.

The common use of MPIO is for virtualization, many people use it with VMWare, KVM, Xen etc to provide redundancy and performance. It also has the advantage of not requiring a managed switch as all it’s tricks are done on the TCP level.