Re: Character limit for rbd block device

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On 11/26/2012 04:52 PM, Josh Durgin wrote:
On 11/26/2012 04:10 PM, brady wrote:
Hello,
     I have a general question. Is there a specific character limit for
rbd block devices? In attempting to map a block device with a name that
is 36 characters or more, I am getting the following error:

rbd map (36+ character name) --user admin --secret /etc/ceph/keyring.key
add failed: (2) No such file or directory

     When using the same command to map a device with 35 characters or
less, the device is mapped as expected. Any insight into this issue
would be greatly appreciated.

-Brady

Which kernel version are you using?

A year ago there was a 40-char limit on objects names in the kernel's
libceph module, hence the failure at 36 char rbd image names (36 char
name + ".rbd" is the format 1 header object name).

This was extended to a 96-char limit in linux 3.2. There's no real limit
in userspace still (http://tracker.newdream.net/issues/1701).

Josh

Thanks, Josh. This information was exactly what we were looking for. Looks like a version issue that we will need to work around. Thanks again!

Brady
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