After going through a number of posts stating about the Big Funnel Issues and going through it after an Exchange 2019 CU update in November 2021. We found earlier on that by migrating the mailboxes that may fix the funnel issue and it resets the Not indexed count back to zero. This is also recommended by the Microsoft initial Exchange engineers, whenever we created any tickets for the problem. We had recently completed the migration to 2019 and found that it had a large number of enormous mailboxes for that to get a solution.
After five months and countless number of Microsoft Engineers, one can drop a setting that can be never heard of and neither have any Google results.
New-SettingOverride -Name "Big Funnel Permanent Retry" -Component "BigFunnel" -Section "BigFunnelFailedItemsQuerySettings" -Parameters @("ExcludePermanentFailures=false") -Reason "Re-Index Messages" -MinVersion "15.2.922.7" -MaxVersion "15.2.986.22
I have used BigFunnelNotIndexed queries across all the mailboxes, ran this rule, waited for some time and ran this query again. Earlier, around one third of the mailboxes had not indexed counts in the triple digits and all of the mailboxes had some large number of them. Once we add this setting override, around 95% of the mailboxes were at zero, and none of them were more than 20.
As far as I know, this setting Big Funnel to always retry where earlier it was marking these products as lost causes. And for most of these retries, it works.
Hope, that this undocumented settings may help you without needing to juggle around terabytes of mail as the Microsoft suggest.
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