On 17-03-09 05:38, Max Yehorov wrote:
I was reading through release notes for 10.2.6 and there was a ticket
rbd: rbd-nbd: disallow mapping images >2TB in size (issue#17219,
pr#11870, Mykola Golub)
default nbd block size is 1k, valid values are from 512 to PAGE_SIZE
rbd_nbd.cc sets blocksize to 512 here:
https://github.com/ceph/ceph/blob/master/src/tools/rbd_nbd/rbd-nbd.cc#L635
Why 512 was chosen for rbd_nbd?
krbd also uses 512 sector size. Is there a reason to use 512 block
size vs 4k AF?
I am also interested in >2TB NBD support and was disapointed when I
couldn't mount 10TB images.
Based on issue in that commit for me it seems to be clear why it was
done - some (most?) kernels in the wild do not support larger sizes. But
it looks like support on unaffected kernels is already in master (not
sure if it got backported to current releases). For reference:
http://tracker.ceph.com/issues/17219 ->
https://github.com/ceph/ceph/pull/11741 ->
http://tracker.ceph.com/issues/18335 ->
https://github.com/ceph/ceph/pull/13229
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