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https://github.com/ceph/ceph-csi.git
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75fa1927fc
To recover from split brain (up+error) state the image need to be
demoted and requested for resync on site-a and then the image on site-b
should gets demoted.The volume should be marked to ready=true when the
image state on both the clusters are up+unknown because during the last
snapshot syncing the data gets copied first and then image state on the
site-a changes to up+unknown.
If the image state on both the sites are up+unknown consider that
complete data is synced as the last snapshot
gets exchanged between the clusters.
* create 10 GB of file and validate the data after resync
* Do Failover when the site-a goes down
* Force promote the image and write data in GiB
* Once the site-a comes back, Demote the image and issue resync
* Demote the image on site-b
* The status will get reflected on the other site when the last
snapshot sync happens
* The image will go to up+unknown state. and complete data will
be copied to site a
* Promote the image on site-a and use it
```bash
csi-vol-5633715e-a7eb-11eb-bebb-0242ac110006:
global_id: e7f9ec55-06ab-46cb-a1ae-784be75ed96d
state: up+unknown
description: remote image demoted
service: a on minicluster1
last_update: 2021-04-28 07:11:56
peer_sites:
name: e47e29f4-96e8-44ed-b6c6-edf15c5a91d6-rook-ceph
state: up+unknown
description: remote image demoted
last_update: 2021-04-28 07:11:41
```
* Do Failover when the site-a goes down
* Force promote the image on site-b and write data in GiB
* Demote the image on site-b
* Once the site-a comes back, Demote the image on site-a
* The images on the both site will go to split brain state
```bash
csi-vol-37effcb5-a7f1-11eb-bebb-0242ac110006:
global_id: 115c3df9-3d4f-4c04-93a7-531b82155ddf
state: up+error
description: split-brain
service: a on minicluster2
last_update: 2021-04-28 07:25:41
peer_sites:
name: abbda0f0-0117-4425-8cb2-deb4c853da47-rook-ceph
state: up+error
description: split-brain
last_update: 2021-04-28 07:25:26
```
* Issue resync
* The images cannot be resynced because when we issue resync
on site a the image on site-b was in demoted state
* To recover from this state (promote and then demote the
image on site-b after sometime)
```bash
csi-vol-37effcb5-a7f1-11eb-bebb-0242ac110006:
global_id: 115c3df9-3d4f-4c04-93a7-531b82155ddf
state: up+unknown
description: remote image demoted
service: a on minicluster1
last_update: 2021-04-28 07:32:56
peer_sites:
name: e47e29f4-96e8-44ed-b6c6-edf15c5a91d6-rook-ceph
state: up+unknown
description: remote image demoted
last_update: 2021-04-28 07:32:41
```
* Once the data is copied we can see that the image state
is moved to up+unknown on both sites
* Promote the image on site-a and use it
Signed-off-by: Madhu Rajanna <madhupr007@gmail.com>
(cherry picked from commit
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|---|---|---|
| .. | ||
| clone.go | ||
| controllerserver.go | ||
| driver.go | ||
| encryption.go | ||
| errors.go | ||
| identityserver.go | ||
| mirror.go | ||
| nodeserver_test.go | ||
| nodeserver.go | ||
| rbd_attach.go | ||
| rbd_journal.go | ||
| rbd_util_test.go | ||
| rbd_util.go | ||
| replicationcontrollerserver.go | ||
| snapshot.go | ||