mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-12-22 10:31:53 +07:00
d81dc4f45b
The following commits will successively transform DRBD into the structure described here. Signed-off-by: Andreas Gruenbacher <agruen@linbit.com> Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
39 lines
1.9 KiB
Plaintext
39 lines
1.9 KiB
Plaintext
This describes the in kernel data structure for DRBD-9. Starting with
|
|
Linux v3.14 we are reorganizing DRBD to use this data structure.
|
|
|
|
Basic Data Structure
|
|
====================
|
|
|
|
A node has a number of DRBD resources. Each such resource has a number of
|
|
devices (aka volumes) and connections to other nodes ("peer nodes"). Each DRBD
|
|
device is represented by a block device locally.
|
|
|
|
The DRBD objects are interconnected to form a matrix as depicted below; a
|
|
drbd_peer_device object sits at each intersection between a drbd_device and a
|
|
drbd_connection:
|
|
|
|
/--------------+---------------+.....+---------------\
|
|
| resource | device | | device |
|
|
+--------------+---------------+.....+---------------+
|
|
| connection | peer_device | | peer_device |
|
|
+--------------+---------------+.....+---------------+
|
|
: : : : :
|
|
: : : : :
|
|
+--------------+---------------+.....+---------------+
|
|
| connection | peer_device | | peer_device |
|
|
\--------------+---------------+.....+---------------/
|
|
|
|
In this table, horizontally, devices can be accessed from resources by their
|
|
volume number. Likewise, peer_devices can be accessed from connections by
|
|
their volume number. Objects in the vertical direction are connected by double
|
|
linked lists. There are back pointers from peer_devices to their connections a
|
|
devices, and from connections and devices to their resource.
|
|
|
|
All resources are in the drbd_resources double-linked list. In addition, all
|
|
devices can be accessed by their minor device number via the drbd_devices idr.
|
|
|
|
The drbd_resource, drbd_connection, and drbd_device objects are reference
|
|
counted. The peer_device objects only serve to establish the links between
|
|
devices and connections; their lifetime is determined by the lifetime of the
|
|
device and connection which they reference.
|