Hello, here is an snippet from the documentation[0] that explains this behavior: *The data pool used to create the file system is the “default” data pool and the location for storing all inode backtrace information, used for hard link management and disaster recovery. For this reason, all inodes created in CephFS have at least one object in the default data pool. If erasure-coded pools are planned for the file system, it is usually better to use a replicated pool for the default data pool to improve small-object write and read performance for updating backtraces.* [0] https://docs.ceph.com/en/latest/cephfs/createfs/ On Thu, Jul 30, 2026 at 12:04 PM Loïc Tortay via ceph-users < ceph-users@ceph.io> wrote:

On 30/07/2026 11:42, Robert Sander via ceph-users wrote:

...

Hi,

we have a CephFS with a replicated data pool and an additional EC data pool. All files store their data in the EC pool.

But "ceph df" shows that the replicated data pool contains over 200 million objects with a total size of 700 bytes. So the vast majority are empty objects.

How can this be?

Hello, The replicated pool is the "default pool" and contains files metadata ? (unlike the "metadata" pool)

Like in this filesystem with ~1.4 billion files and 85 million directories: POOL ID PGS STORED OBJECTS USED %USED MAX AVAIL cephfs_EC_data 3 8192 6.6 PiB 3.00G 8.3 PiB 79.90 1.7 PiB cephfs_metadata 4 256 778 GiB 84.70M 2.3 TiB 3.38 22 TiB cephfs_default 5 128 0 B 1.37G 0 B 0 22 TiB

Loïc. -- | Loic Tortay <tortay@cc.in2p3.fr> - IN2P3 Computing Centre | _______________________________________________ ceph-users mailing list -- ceph-users@ceph.io To unsubscribe send an email to ceph-users-leave@ceph.io