Hello, thank you for your response. Erasure Coding gets better and we really cannot afford the storage overhead of x3 replication. Anyway, as I understand the problem, it is also present with replication, just less amplified (blocks are not divided between OSDs, just replicated fully). Le 2021-02-02 16:50, Steven Pine a écrit :

You are unlikely to avoid the space amplification bug by using larger block sizes. I honestly do not recommend using an EC pool, it is generally less performant and EC pools are not as well supported by the ceph development community.

On Tue, Feb 2, 2021 at 5:11 AM Gilles Mocellin <gilles.mocellin@nuagelibre.org> wrote:

...

Hello,

As we know, with 64k for bluestore_min_alloc_size_hdd (I'm only using HDDs), in certain conditions, especially with erasure coding, there's a leak of space while writing objects smaller than 64k x k (EC:k+m).

Every object is divided in k elements, written on different OSD.

My main use case is big (40TB) RBD images mounted as XFS filesystems on Linux servers, exposed to our backup software. So, it's mainly big files.

My though, but I'd like some other point of view, is that I could deal with the amplification by using bigger block sizes on my XFS filesystems. Instead of reducing bluestore_min_alloc_size_hdd on all OSDs.

What do you think ? _______________________________________________ ceph-users mailing list -- ceph-users@ceph.io To unsubscribe send an email to ceph-users-leave@ceph.io

--

Steven Pine

E steven.pine@webair.com | P 516.938.4100 x

Webair | 501 Franklin Avenue Suite 200, Garden City NY, 11530

webair.com [1]

[2] [3] [4]

NOTICE: This electronic mail message and all attachments transmitted with it are intended solely for the use of the addressee and may contain legally privileged proprietary and confidential information. If the reader of this message is not the intended recipient, or if you are an employee or agent responsible for delivering this message to the intended recipient, you are hereby notified that any dissemination, distribution, copying, or other use of this message or its attachments is strictly prohibited. If you have received this message in error, please notify the sender immediately by replying to this message and delete it from your computer.

Links: ------ [1] http://webair.com [2] https://www.facebook.com/WebairInc/ [3] https://twitter.com/WebairInc [4] https://www.linkedin.com/company/webair