# Applying knobs dynamically

**URL:** <https://forums.foundationdb.org/t/applying-knobs-dynamically/2355>\
**Category:** Running FoundationDB\
**Created:** [September 22, 2020, 11:38pm UTC](https://forums.foundationdb.org/t/applying-knobs-dynamically/2355 "2020-09-22T23:38:57Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![ajames](https://avatars.discourse-cdn.com/v4/letter/a/9de0a6/32.png) [@ajames](https://forums.foundationdb.org/u/ajames)\
**Post date:** [September 22, 2020, 11:38pm UTC](https://forums.foundationdb.org/t/applying-knobs-dynamically/2355/1 "2020-09-22T23:38:57Z")

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We are running 16 node fdb cluster (6.2). When we add more nodes, it takes days for data cleanup to complete and regain full disk space. Saw that we can use `--knob_cleaning_inerval=0.1` to increase cleanup speed. Is there a way to dynamically apply this to all fdb processes rather than editing `foundationdb.conf` file?

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**Author:** ![ajbeamon](https://sea1.discourse-cdn.com/foundationdb/user_avatar/forums.foundationdb.org/ajbeamon/32/13_2.png) [@ajbeamon](https://forums.foundationdb.org/u/ajbeamon)\
**Post date:** [September 23, 2020, 5:43pm UTC](https://forums.foundationdb.org/t/applying-knobs-dynamically/2355/2 "2020-09-23T17:43:49Z")

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Currently, there is no mechanism to set knobs besides passing the knob option to every process you want to affect at startup time. If you are using fdbmonitor, then this requires updating your `foundationdb.conf` files.

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**Author:** ![ajames](https://avatars.discourse-cdn.com/v4/letter/a/9de0a6/32.png) [@ajames](https://forums.foundationdb.org/u/ajames)\
**Post date:** [September 23, 2020, 6:09pm UTC](https://forums.foundationdb.org/t/applying-knobs-dynamically/2355/3 "2020-09-23T18:09:22Z")

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Thank you @ajbeamon for the reply. Are there any plans to add the same in near future?

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**Author:** ![ajbeamon](https://sea1.discourse-cdn.com/foundationdb/user_avatar/forums.foundationdb.org/ajbeamon/32/13_2.png) [@ajbeamon](https://forums.foundationdb.org/u/ajbeamon)\
**Post date:** [September 23, 2020, 7:36pm UTC](https://forums.foundationdb.org/t/applying-knobs-dynamically/2355/4 "2020-09-23T19:36:55Z")

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There have been discussions about trying to make knobs configurable through something like `fdbcli`, potentially even changing some while the cluster is running, but there are a number of things that make that somewhat complex. Partly for that reason, I don’t think it’s currently on the roadmap. At the same time, I think it’s a nice-to-have feature that we’d like to see make it in some day.