Based on kernel version 4.16.1. Page generated on 2018-04-09 11:52 EST.
1 This describes the in kernel data structure for DRBD-9. Starting with 2 Linux v3.14 we are reorganizing DRBD to use this data structure. 3 4 Basic Data Structure 5 ==================== 6 7 A node has a number of DRBD resources. Each such resource has a number of 8 devices (aka volumes) and connections to other nodes ("peer nodes"). Each DRBD 9 device is represented by a block device locally. 10 11 The DRBD objects are interconnected to form a matrix as depicted below; a 12 drbd_peer_device object sits at each intersection between a drbd_device and a 13 drbd_connection: 14 15 /--------------+---------------+.....+---------------\ 16 | resource | device | | device | 17 +--------------+---------------+.....+---------------+ 18 | connection | peer_device | | peer_device | 19 +--------------+---------------+.....+---------------+ 20 : : : : : 21 : : : : : 22 +--------------+---------------+.....+---------------+ 23 | connection | peer_device | | peer_device | 24 \--------------+---------------+.....+---------------/ 25 26 In this table, horizontally, devices can be accessed from resources by their 27 volume number. Likewise, peer_devices can be accessed from connections by 28 their volume number. Objects in the vertical direction are connected by double 29 linked lists. There are back pointers from peer_devices to their connections a 30 devices, and from connections and devices to their resource. 31 32 All resources are in the drbd_resources double-linked list. In addition, all 33 devices can be accessed by their minor device number via the drbd_devices idr. 34 35 The drbd_resource, drbd_connection, and drbd_device objects are reference 36 counted. The peer_device objects only serve to establish the links between 37 devices and connections; their lifetime is determined by the lifetime of the 38 device and connection which they reference.
