From: Dan van der Ster Date: Wed, 19 Jan 2022 14:17:15 +0000 (+0100) Subject: mds: mds_oft_prefetch_dirfrags default to false X-Git-Tag: v18.0.0~1423^2 X-Git-Url: http://git-server-git.apps.pok.os.sepia.ceph.com/?a=commitdiff_plain;h=e19ef199c94406afd220e574e24d52c03d9b67a3;p=ceph.git mds: mds_oft_prefetch_dirfrags default to false The oft dirfrag prefetch is unpredictable and dangerous because it can delay rejoin by several minutes and balloon memory usage well beyond the mds_cache_memory_limit. In the worst cases this can cause an OOM loop if the memory required for prefetch exceeds the physical memory. The PR which introduced mds_oft_prefetch_dirfrags also optimized the client behaviour to eliminate the bad effects of disabling dirfrags prefetch. And commit d3946e36f89203bd5c7f51c3a73d1a17a4d19863 has been testing setting this option to false. We therefore should default the option to false. Operators can still manually enable it if they know it can speedup their use-cases. Related-to: https://tracker.ceph.com/issues/45835 Fixes: https://tracker.ceph.com/issues/53952 Signed-off-by: Dan van der Ster --- diff --git a/src/common/options/mds.yaml.in b/src/common/options/mds.yaml.in index cfe678ed464d..697710484c8f 100644 --- a/src/common/options/mds.yaml.in +++ b/src/common/options/mds.yaml.in @@ -834,7 +834,7 @@ options: type: bool level: advanced desc: prefetch dirfrags recorded in open file table on startup - default: true + default: false services: - mds flags: