[Gluster-devel] very strange in disk reads

[Krishna Srinivas]

Billy,

As long as there are no error messages in the log and "wc" gives correct
results, there is no need to worry. However your observation is strange,
but lets see if it can be explained...

what are the sizes of the two files?
are the order of sub vols same in both client confs?
do you use "option read-sobvolume" in afr definition?
what are the inode numbers of the two files on node1?

>  We are using round robin for writes (probably unrelated)

Where are you using RR for writes?

Thanks
Krishna

On Thu, Feb 28, 2008 at 11:56 PM, billy cokalopolous
<billy.cokalopolous at gmail.com> wrote:
> Hello,
>
>  I have AFR setup on 2 nodes. The nodes are on a wireless connection, so I
>  can really see a performance lag when reading data.  On each node, a
>  glusterfs client is mounted pointing to the same glusterfs directory.
>
>
>
>  Here is the strange part:
>
>  node 1:
>  read file1.txt
>  read file2.txt
>  node 2:
>  read file1.txt
>  read file2.txt
>
>  We are seeing inconsistent performance from one of the nodes. Suddenly
>  instead of reading over the gluster fs network, it seems to be reading the
>  file only from the local node's gluster filesystem as if failover occurred.
>
>  word count on file1.txt  takes 5 seconds on node 1 and node 2
>
>  Then all of a sudden word count on file1.txt takes .2 seconds on node 1, but
>  same 5 seconds on node 2, almost as if the client on node 1 saw a terminated
>  connection of node 2 and only pulled locally.
>
>  Now here is the stranger part.
>  file2.txt takes 5 seconds to obtain a word count on node 1 and node 2
>  consistently. Even when file1.txt on node 1 takes .2 seconds to obtain a
>  word count, file2.txt on that same node still takes 5 seconds.
>
>  We are using round robin for writes (probably unrelated)
>
>  No errors or messages of disconnect in glusterfs.log or glusterfsd.log. All
>  seems healthy.
>
>  Using posix-locks and AFR. No other features/etc
>
>  Any ideas? Thanks.
>
>  Billy
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