Confusing documentation about ceph osd pool set pg_num
Hi, We need to increase the number of PG’s for a pool on a Pacific cluster. I know we can easily do that using: ceph osd pool set $name pg_num $amount However, the documentation [1] states (both for Pacific and for Squid) that you need to upgrade pgp_num as well. But, I seem to remember that in newer versions, pgp_num will be upgraded automatically. And this message claims that as well [2] So which one is true? :) [1]: https://docs.ceph.com/en/squid/rados/operations/placement-groups/#setting-th... [2]: https://lists.ceph.io/hyperkitty/list/ceph-users@ceph.io/message/F6PLHO7BGRI... — Mark Schouten CTO, Tuxis B.V. +31 318 200208 / mark@tuxis.nl
We need to increase the number of PG’s for a pool on a Pacific cluster. I know we can easily do that using:
ceph osd pool set $name pg_num $amount
However, the documentation [1] states (both for Pacific and for Squid) that you need to upgrade pgp_num as well. But, I seem to remember that in newer versions, pgp_num will be upgraded automatically. And this message claims that as well [2]
You set the pg_num and the balancer will split a few at a time until pgp_num reaches pg_num. At some point, ceph started complaining if you try to set pgp_num manually. -- May the most significant bit of your life be positive.
Hi,
You set the pg_num and the balancer will split a few at a time until pgp_num reaches pg_num. At some point, ceph started complaining if you try to set pgp_num manually. Ok. So the documentation is incorrect, or at least incomplete?
— Mark Schouten CTO, Tuxis B.V. +31 318 200208 / mark@tuxis.nl
I’m sure the documentation is incomplete, but I’m working on it. Zac Dover Head of Docs Ceph Foundation Sent from [Proton Mail](https://proton.me/mail/home) for iOS On Mon, Feb 3, 2025 at 22:38, Mark Schouten <[mark@tuxis.nl](mailto:On Mon, Feb 3, 2025 at 22:38, Mark Schouten <<a href=)> wrote:
Hi,
You set the pg_num and the balancer will split a few at a time until pgp_num reaches pg_num. At some point, ceph started complaining if you try to set pgp_num manually. Ok. So the documentation is incorrect, or at least incomplete?
— Mark Schouten CTO, Tuxis B.V. +31 318 200208 / mark@tuxis.nl _______________________________________________ ceph-users mailing list -- ceph-users@ceph.io To unsubscribe send an email to ceph-users-leave@ceph.io
Janne, Is it still possible to set pgp_num manually? I need to know so that I can properly write this section. Zac On Monday, February 3rd, 2025 at 10:43 PM, Zac Dover <zac.dover@proton.me> wrote:
I’m sure the documentation is incomplete, but I’m working on it.
Zac Dover Head of Docs Ceph Foundation
Sent from [Proton Mail](https://proton.me/mail/home) for iOS
On Mon, Feb 3, 2025 at 22:38, Mark Schouten <[mark@tuxis.nl](mailto:On Mon, Feb 3, 2025 at 22:38, Mark Schouten <<a href=)> wrote:
Hi,
You set the pg_num and the balancer will split a few at a time until pgp_num reaches pg_num. At some point, ceph started complaining if you try to set pgp_num manually. Ok. So the documentation is incorrect, or at least incomplete?
— Mark Schouten CTO, Tuxis B.V. +31 318 200208 / mark@tuxis.nl _______________________________________________ ceph-users mailing list -- ceph-users@ceph.io To unsubscribe send an email to ceph-users-leave@ceph.io
I have raised a documentation PR that we can use to clear up the language around when it is appropriate (if ever) to manually set pgp_num: https://github.com/ceph/ceph/pull/61626 Please join me there for discussion of this. Zac Dover Head of Docs Ceph Foundation On Monday, February 3rd, 2025 at 11:36 PM, Zac Dover <zac.dover@proton.me> wrote:
Janne,
Is it still possible to set pgp_num manually?
I need to know so that I can properly write this section.
Zac
On Monday, February 3rd, 2025 at 10:43 PM, Zac Dover <zac.dover@proton.me> wrote:
I’m sure the documentation is incomplete, but I’m working on it.
Zac Dover Head of Docs Ceph Foundation
Sent from [Proton Mail](https://proton.me/mail/home) for iOS
On Mon, Feb 3, 2025 at 22:38, Mark Schouten <[mark@tuxis.nl](mailto:On Mon, Feb 3, 2025 at 22:38, Mark Schouten <<a href=)> wrote:
Hi,
You set the pg_num and the balancer will split a few at a time until pgp_num reaches pg_num. At some point, ceph started complaining if you try to set pgp_num manually. Ok. So the documentation is incorrect, or at least incomplete?
— Mark Schouten CTO, Tuxis B.V. +31 318 200208 / mark@tuxis.nl _______________________________________________ ceph-users mailing list -- ceph-users@ceph.io To unsubscribe send an email to ceph-users-leave@ceph.io
participants (3)
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Janne Johansson
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Mark Schouten
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Zac Dover