Ceph

Ceph: RBD fails to map an image to a block device

When I tried to map an image to block device, I got the below error using ceph “rbd map” command:

#rbd create image01 --size 1024 -p rbdbench
#rbd map image01 -p rbdbench --name client.admin
rbd: sysfs write failed
RBD image feature set mismatch. You can disable features unsupported by the
kernel with "rbd feature disable".
In some cases useful info is found in syslog - try "dmesg | tail" or so.
rbd: map failed: (6) No such device or address

This can be fixed by passing appropriate features enabled either manually or set he default feature set in the Ceph  (/etc/ceph/ceph.conf) configuration.

 To fix the above issue: To resolve this issue, edit

Option#1:  Added the line in ceph config i.e /etc/ceph/ceph.conf file:

rbd default features = 3

Option#2: Alternatively, we can enable the “layering” feature by adding “--image-feature layering" flag, when we create the image. For example:

#rbd create image02 --size 1024 --pool rbdbench --image-feature layering
# rbd map image02 -p rbdbench --name client.admin
/dev/rbd1

 

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