Big troubles upgrading elastic cluter

Hi,

I got a big issue upgrading my elastic cluster.
I think the only option is to stop all 5 servers, restore the FS backup I have and re-start the 5 servers.

I would like to get advice to restart my cluster.

Thank you for helping me.

Jean-Marc

I finally removed all the indices with 2 unassigned shards on 2.
I suppose I cannot recover indices without at least one assigned shards.
I finally lost some data but the cluster is back.

Quoting the docs:

WARNING: The only reliable and supported way to back up a cluster is by taking a snapshot . You cannot back up an Elasticsearch cluster by making copies of the data directories of its nodes. There are no supported methods to restore any data from a filesystem-level backup. If you try to restore a cluster from such a backup, it may fail with reports of corruption or missing files or other data inconsistencies, or it may appear to have succeeded having silently lost some of your data.

You should restore from the snapshot you took before starting the upgrade, not from a filesystem backup.

Thnak's for the info, David.
I just deleted the indices without shards.
As I have no space available to snapshot the 3TB data of the cluster, I knew the risk was to loose data.
What happened during my upgrade.