A > B, B > A, Sites Basics

In case that you have 2 or more of geo locations, infrastructure you may need can look something like this ?

                                                             [___Internet___]                                                        
  _____________________________________________________             |             _____________________________________________________ 
 | [ an-node01 ]                                       |            |            |                                       [ an-node02 ] |
 |                       ____________    ______________|        ____|____        |______________    ____________                       |
 |                      |    vbr2    |--| bond2        |       | [ IFN ] |       |        bond2 |--|   vbr2     |                      |
 |  _________________   | 10.255.0.1 |  | ______       |      _|_________|_      |       ______ |  | 10.255.0.2 |  ................... |
 | | [ vm0001-dev ]  |  |____________|  || eth2 =--\   |     |   Switch 1  |     |   /--= eth2 ||  |____________|  :  [ vm0001-dev ] : |
 | | [ Dev Server ]  |    | | : :       ||_____|    \--=-----|_____________|-----=--/    |_____||       | | : :    :  [ Dev Server ] : |
 | |           ______|    | | : :       | ______    /--=-----|   Switch 2  |-----=--\    ______ |       | | : :    :.......          : |
 | |          | eth0 =----/ | : :       || eth5 =--/   |     |_____________|     |   \--= eth5 ||       | | : :----= eth0 :          : |
 | |          |_____||      | : :       ||_____|       |                         |       |_____||       | | :      ::.....:          : |
 | |      10.254.0.1 |      | : :       |______________|                         |______________|       | | :      :                 : |
 | |_________________|      | : :        ______________|                         |______________        | | :      :.................: |
 |                          | : :       | bond1        |        _________        |        bond1 |       | | :                          |
 |  _________________       | : :       |   10.10.0.1  |       | [ SN  ] |       | 10.10.0.2    |       | | :      ................... |
 | | [ vm0002-web ]  |      | : :       | ______       |      _|_________|_      |       ______ |       | | :      :  [ vm0002-web ] : |
 | | [ Web Server ]  |      | : :       || eth1 =--\   |     |   Switch 1  |     |   /--= eth1 ||       | | :      :  [ Web Server ] : |
 | |           ______|      | : :       ||_____|    \--=-----|_____________|-----=--/    |_____||       | | :      :.......          : |
 | |          | eth0 =------/ : :       | ______    /--=-----|   Switch 2  |-----=--\    ______ |       | | :------= eth0 :          : |
 | |          |_____||        : :       || eth4 =--/   |     |_____________|     |   \--= eth4 ||       | |        ::.....:          : |
 | |      10.254.0.2 |        : :       ||_____|       |                         |       |_____||       | |        :                 : |
 | |_________________|        : :       |______________|                         |______________|       | |        :.................: |
 |                            : :        ______________|                         |______________        | |                            |
 | ...................        : :       | bond0        |        _________        |        bond0 |       | |         _________________  |
 | : [ vm0003-db  ]  :        : :       |   10.20.0.1  |       | [ BCN ] |       | 10.20.0.2    |       | |        |  [ vm0003-db  ] | |
 | : [ DB Server  ]  :        : :       | ______       |      _|_________|_      |       ______ |       | |        |  [ DB Server  ] | |
 | :          .......:        : :       || eth0 =--\   |  /--|   Switch 1  |--\  |   /--= eth0 ||       | |        |______           | |
 | :          : eth0 =--------: :       ||_____|    \--=--+--|_____________|--+--=--/    |_____||       | \--------= eth0 |          | |
 | :          :.....::          :       | ______    /--=--+--|   Switch 2  |--+--=--\    ______ |       |          ||_____|          | |
 | :                 :          :       || eth3 =--/   |  |  |_____________|  |  |   \--= eth3 ||       |          | 10.254.0.3      | |
 | :.................:          :       ||_____|       |  |     |       |     |  |       |_____||       |          |_________________| |
 |                              :       |______________|  |     |       |     |  |______________|       |                              |
 | ...................          :                      |  |     |       |     |  |                      |           _________________  |
 | : [ vm0004-win ]  :          :                      |  |     |       |     |  |                      |          |  [ vm0004-win ] | |
 | : [ MS Server  ]  :          :                      |  |     |       |     |  |                      |          |  [ MS Server  ] | |
 | :          .......:          :                      |  |     |       |     |  |                      |          |______           | |
 | :          : NIC0 =----------:                      |  |     |       |     |  |                      \----------= NIC0 |          | |
 | :          :.....::                           ______|  |     |       |     |  |______                           ||_____|          | |
 | :                 :                  _____   | IPMI =--/     |       |     \--= IPMI |   _____                  | 10.254.0.4      | |
 | :.................:                 [_BMC_]--|_____||        |       |        ||_____|--[_BMC_]                 |_________________| |
 |                                                     |        |       |        |                                                     |
 |                                 ______ ______       |        |       |        |       ______ ______                                 |
 |                                | PSU1 | PSU2 |      |        |       |        |      | PSU2 | PSU1 |                                |
 |________________________________|______|______|______|        |       |        |______|______|______|________________________________|
                                       || ||                ____|_     _|____                || ||                                      
                                       || ||               | PDU1 |   | PDU2 |               || ||                                      
                                       || ||               |______|   |______|               || ||                                      
                                       || ||                 || ||     || ||                 || ||                                      
                                       || \\===[ Power 1 ]===// ||     || \\===[ Power 1 ]===// ||                                      
                                       \\======[ Power 2 ]======||=====//                       ||                                      
                                                                \\=============[ Power 2 ]======//


#### Storage part

 _________________________________________________                 _________________________________________________ 
| [ an-node01 ]                                   |               |                                   [ an-node02 ] |
|  ________       __________                      |               |                      __________       ________  |
| [_disk_1_]--+--[_/dev/sda_]                     |               |                     [_/dev/sda_]--+--[_disk_1_] |
|  ________   |    |   ___________    _______     |               |     _______    ___________   |    |   ________  |
| [_disk_2_]--+    +--[_/dev/sda1_]--[_/boot_]    |               |    [_/boot_]--[_/dev/sda1_]--+    +--[_disk_2_] |
|  ________   |    |   ___________    _______     |               |    ________    ___________   |    |   ________  |
| [_disk_3_]--+    +--[_/dev/sda2_]--[__swap_]    |               |   [__swap__]--[_/dev/sda2_]--+    +--[_disk_3_] |
|  ________   |    |   ___________    ___         |               |         ___    ___________   |    |   ________  |
| [_disk_4_]--/    +--[_/dev/sda3_]--[_/_]        |               |        [_/_]--[_/dev/sda3_]--+    \--[_disk_4_] |
|                  |   ___________                |               |                ___________   |                  |
|                  +--[_/dev/sda5_]------------\  |               |  /------------[_/dev/sda5_]--+                  |
|                  |   ___________             |  |               |  |             ___________   |                  |
|                  +--[_/dev/sda6_]----------\ |  |               |  | /----------[_/dev/sda6_]--+                  |
|                  |   ___________           | |  |               |  | |           ___________   |                  |
|                  \--[_/dev/sda7_]--------\ | |  |               |  | | /--------[_/dev/sda7_]--/                  |
|        _______________    ____________   | | |  |               |  | | |   ____________    _______________        |
|    /--[_Clustered_LVM_]--[_/dev/drbd2_]--/ | |  |               |  | | \--[_/dev/drbd2_]--[_Clustered_LVM_]--\    |
|   _|__                     |   _______     | |  |               |  | |      |   _______                    __|_   |
|  [_PV_]                    \--{_bond1_}    | |  |               |  | |      \--{_bond1_}                  [_PV_]  |
|   _|________                               | |  |               |  | |                               ________|_   |
|  [_an02-vg0_]                              | |  |               |  | |                              [_an02-vg0_]  |
|    |   ________________________    ....... | |  |               |  | |  _____     ________________________   |    |
|    +--[_/dev/an02-vg0/vm0003_1_]---:.vm3.: | |  |               |  | | [_vm3_]---[_/dev/an02-vg0/vm0003_1_]--+    |
|    |   ________________________    ....... | |  |               |  | |  _____     ________________________   |    |
|    \--[_/dev/an02-vg0/vm0004_1_]---:.vm4.: | |  |               |  | | [_vm4_]---[_/dev/an02-vg0/vm0004_1_]--/    |
|          _______________    ____________   | |  |               |  | |   ____________    _______________          |
|      /--[_Clustered_LVM_]--[_/dev/drbd1_]--/ |  |               |  | \--[_/dev/drbd1_]--[_Clustered_LVM_]--\      |
|     _|__                     |   _______     |  |               |  |      |   _______                    __|_     |
|    [_PV_]                    \--{_bond1_}    |  |               |  |      \--{_bond1_}                  [_PV_]    |
|     _|________                               |  |               |  |                               ________|_     |
|    [_an01-vg0_]                              |  |               |  |                              [_an01-vg0_]    |
|      |   ________________________     _____  |  |               |  | .......    ________________________   |      |
|      +--[_/dev/an01-vg0/vm0001_1_]---[_vm1_] |  |               |  | :.vm1.:---[_/dev/an01-vg0/vm0001_1_]--+      |
|      |   ________________________     _____  |  |               |  | .......    ________________________   |      |
|      \--[_/dev/an01-vg0/vm0002_1_]---[_vm2_] |  |               |  | :.vm2.:---[_/dev/an01-vg0/vm0002_1_]--/      |
|            _______________    ____________   |  |               |  |   ____________    _______________            |
|        /--[_Clustered_LVM_]--[_/dev/drbd0_]--/  |               |  \--[_/dev/drbd0_]--[_Clustered_LVM_]--\        |
|       _|__                     |   _______      |               |       |   _______                    __|_       |
|      [_PV_]                    \--{_bond1_}     |               |       \--{_bond1_}                  [_PV_]      |
|       _|__________                              |               |                              __________|_       |
|      [_shared-vg0_]                             |               |                             [_shared-vg0_]      |
|       _|_________________________               |               |               _________________________|_       |
|      [_/dev/shared-vg0/lv_shared_]              |               |              [_/dev/shared-vg0/lv_shared_]      |
|        |   ______    _________                  |               |                  _________    ______   |        |
|        \--[_GFS2_]--[_/shared_]                 |               |                 [_/shared_]--[_GFS2_]--/        |
|                                          _______|   _________   |_______                                          |
|                                         | bond1 =--| Storage |--= bond1 |                                         |
|                                         |______||  | Network |  ||______|                                         |
|_________________________________________________|  |_________|  |_________________________________________________|

Let's look at two scenarios showing how locks are handled using CPG; Storage part: Messages can only be sent to the members of the CPG while the node has a totem token from corosync.

Copyleft Enes Bosnić aka n00b 1977 - 2020 enes.bosnic.net