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mon,mds: make standby-replay state more capable #4

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ifed01 wants to merge 2 commits intomasterfrom
wip-ifed-many-standby-replay-mds
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mon,mds: make standby-replay state more capable #4
ifed01 wants to merge 2 commits intomasterfrom
wip-ifed-many-standby-replay-mds

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@ifed01 ifed01 commented Dec 6, 2025 •
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This allows 2 standby-replay daemons and permits cephfs scrubbing at standby-replay MDS.

To fully benefit from this PR one can use 'ceph mds freeze ' command to 'freeze' specific MDS. This leaves the latter in standby-replay mode permanently but lets other daemons to cycle through their states as designed. Hence FS keeps functioning properly with an additional standby-replay daemon. Which gets an ability to monitor FS in parallel this way.

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ifed01 added 2 commits December 6, 2025 00:44
@ifed01
mds,mon: permit 2 MDS-es in standby-replay state
c8bea0f 
Signed-off-by: Igor Fedotov <igor.fedotov@croit.io>
@ifed01
mds: permit scrub in standby-replay
dbf475d 
Signed-off-by: Igor Fedotov <igor.fedotov@croit.io>
sajibreadd-croit
sajibreadd-croit reviewed Dec 9, 2025
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src/mon/MDSMonitor.cc
Comment on lines +2448 to +2455
int followables = mds_map.is_followable(rank);
if (followables < 2 ) {
dout(1) << " setting mds." << info->global_id
<< " to follow mds rank " << rank << dendl;
fsmap.assign_standby_replay(info->global_id, fs.get_fscid(), rank);
do_propose = true;
changed = true;
break;
//break;
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Is it about having at least 2 standby-replay mds?

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@ifed01 ifed01 Dec 9, 2025

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Generally this should be rather configurable but for now this allows up to 2 MDS-es in standby-replay mode.

sajibreadd-croit
sajibreadd-croit approved these changes Dec 9, 2025
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LGTM

sajibreadd-croit pushed a commit that referenced this pull request Feb 11, 2026
@Matan-B
Revert "common/options: fix heap-use-after-free by using never-destro…
77da5ac 
…yed static"

```
Jan 20 09:27:16 ceph-node-0 ceph-e818662e-f5e1-11f0-b263-525400908ba7-osd-1[12300]: AddressSanitizer:DEADLYSIGNAL
Jan 20 09:27:16 ceph-node-0 ceph-e818662e-f5e1-11f0-b263-525400908ba7-osd-1[12300]: =================================================================
Jan 20 09:27:16 ceph-node-0 ceph-e818662e-f5e1-11f0-b263-525400908ba7-osd-1[12300]: ==3==ERROR: AddressSanitizer: stack-overflow on address 0x7b512f6c8dd8 (pc 0x0000046e7a72 bp 0x7b512de7c900 sp 0x7b512f6c8dd8 T0)
Jan 20 09:27:17 ceph-node-0 ceph-e818662e-f5e1-11f0-b263-525400908ba7-osd-1[12300]:     #0 0x0000046e7a72 in get_global_options() (/usr/bin/ceph-osd-crimson+0x46e7a72) (BuildId: 2a86043f51c9be9cb19801e276fb3ee36239556a)
Jan 20 09:27:17 ceph-node-0 ceph-e818662e-f5e1-11f0-b263-525400908ba7-osd-1[12300]:     #1 0x0000046e540e in build_options() (/usr/bin/ceph-osd-crimson+0x46e540e) (BuildId: 2a86043f51c9be9cb19801e276fb3ee36239556a)
Jan 20 09:27:17 ceph-node-0 ceph-e818662e-f5e1-11f0-b263-525400908ba7-osd-1[12300]:     #2 0x0000033b7949 in get_ceph_options() (/usr/bin/ceph-osd-crimson+0x33b7949) (BuildId: 2a86043f51c9be9cb19801e276fb3ee36239556a)
Jan 20 09:27:17 ceph-node-0 ceph-e818662e-f5e1-11f0-b263-525400908ba7-osd-1[12300]:     #3 0x000003440540 in md_config_t::md_config_t(ConfigValues&, ConfigTracker const&, bool) (/usr/bin/ceph-osd-crimson+0x3440540) (BuildId: 2a860>
Jan 20 09:27:17 ceph-node-0 ceph-e818662e-f5e1-11f0-b263-525400908ba7-osd-1[12300]:     #4 0x0000046856a8 in crimson::common::ConfigProxy::ConfigProxy(EntityName const&, std::basic_string_view<char, std::char_traits<char> >) (/usr>
Jan 20 09:27:17 ceph-node-0 ceph-e818662e-f5e1-11f0-b263-525400908ba7-osd-1[12300]:     #5 0x000000eb6cb5 in seastar::shared_ptr_count_for<crimson::common::ConfigProxy>::shared_ptr_count_for<EntityName&, std::__cxx11::basic_string>
..
Jan 20 09:27:17 ceph-node-0 ceph-e818662e-f5e1-11f0-b263-525400908ba7-osd-1[12300]:     ceph#40 0x000000ed6434 in seastar::future<int> seastar::futurize<int>::apply<crimson::osd::_get_early_config(int, char const**)::{lambda()#1}::ope>
Jan 20 09:27:17 ceph-node-0 ceph-e818662e-f5e1-11f0-b263-525400908ba7-osd-1[12300]:     ceph#41 0x000000ed672b in seastar::async<crimson::osd::_get_early_config(int, char const**)::{lambda()#1}::operator()() const::{lambda()#1}>(seast>
```

This reverts commit 1ab0a8c.

Fixes: https://tracker.ceph.com/issues/74481

Signed-off-by: Matan Breizman <mbreizma@redhat.com>
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