From b77df851b1f4ad408ee80d02a5bf15c23e2f9afc Mon Sep 17 00:00:00 2001 From: Brendan Cully Date: Thu, 14 Nov 2024 09:07:09 -0800 Subject: [PATCH] Add warning about restart migration (#116769) We have gotten more than one SDH due to customers not understanding why restarts involving fully-mounted indices can pull a lot of data from the snapshot tier, so it may help to be more explicit about why this happens and how it can be avoided. --- docs/reference/searchable-snapshots/index.asciidoc | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/docs/reference/searchable-snapshots/index.asciidoc b/docs/reference/searchable-snapshots/index.asciidoc index a38971a0bae6..8b0b3dc57686 100644 --- a/docs/reference/searchable-snapshots/index.asciidoc +++ b/docs/reference/searchable-snapshots/index.asciidoc @@ -176,10 +176,10 @@ nodes that have a shared cache. ==== Manually mounting snapshots captured by an Index Lifecycle Management ({ilm-init}) policy can interfere with {ilm-init}'s automatic management. This may lead to issues such as data loss -or complications with snapshot handling. +or complications with snapshot handling. For optimal results, allow {ilm-init} to manage -snapshots automatically. +snapshots automatically. <>. ==== @@ -293,6 +293,14 @@ repository. If you wish to search data across multiple regions, configure multiple clusters and use <> or <> instead of {search-snaps}. +It's worth noting that if a searchable snapshot index has no replicas, then when the node +hosting it is shut down, allocation will immediately try to relocate the index to a new node +in order to maximize availability. For fully mounted indices this will result in the new node +downloading the entire index snapshot from the cloud repository. Under a rolling cluster restart, +this may happen multiple times for each searchable snapshot index. Temporarily +disabling allocation during planned node restart will prevent this, as described in +the <>. + [discrete] [[back-up-restore-searchable-snapshots]] === Back up and restore {search-snaps}