On 02/26/2014 07:42 PM, Zhang Huan wrote:
Hello guys,
Anyone know about my question?
Zhang Huan
On Sun, Feb 23, 2014 at 11:28 AM, Zhang Huan <zhh...@gmail.com
<mailto:zhh...@gmail.com>> wrote:
Hello all,
While reading codes about how to choose healing source, there is
one thing that confuse me. Say we have 3 replica, and 2 of them
are OK and the left one is outdated due to temporary IO failure.
For some reason, one of the 2 correct replica is truncated to 0
due to some underlying correction. Will glusterfs kick the 0 size
file out? or still consider it a correct one and may corrupt the
left correct replica by healing?
Out of the two correct replicas, gluster will pick the first healthy
replica brick as source [see afr_sh_select_source()]. If that brick is
truncated at the back-end due to 'underlying correction' (not sure what
that means), then yes I'm afraid it will still be considered as correct
source and you would get zero byte file in other 2 bricks because of the
healing.
In function afr_mark_sources(), it kicks 0 size file out when all
nodes are innocent. Even when all nodes are fools, the file with
largest size will be chosen as source. When it comes to the case
that there is wise nodes, it won't further check file size.
Considering different file size of replicate will trigger healing
to work, I am wondering if there is any reason behind the code?
The changelog extended attributes are marked by AFR based on the result
of whether the file operation succeeded or not on each of the replica.
It uses those attributes to determine the source/sink. Direct
modification of the file at the brick will invalidate any meaning that
the changelog holds.
Thanks,
Ravi
Thanks.
Zhang Huan
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