Thanks, Krutika!

So, if I understand you correctly...if both Brick 1 and Brick 2 have a good 
copy of the file, then we can't tell for sure if the file will be read only 
from Brick 1 all the time and not Brick 2? in other words, for read#1, the file 
could be read from brick 2 and for another read which could happen a few 
minutes later, the file could be read from brick 1?

________________________________
From: Krutika Dhananjay <[email protected]>
Sent: Friday, April 10, 2015 9:30 PM
To: Bharathram Sivasubramanian
Cc: [email protected]
Subject: Re: [Gluster-users] Question on file reads from a distributed 
replicated volume



________________________________
From: "Bharathram Sivasubramanian" <[email protected]>
To: [email protected]
Sent: Saturday, April 11, 2015 3:03:48 AM
Subject: [Gluster-users] Question on file reads from a distributed        
replicated volume

Let us assume that we have a distributed replicated gluster volume with 4 
bricks. Brick 1 is replicating its data with Brick 2 and Brick 3 is replicating 
its data with Brick 4. Suppose a file called aa.txt is present and replicated 
on Bricks 1 & 2. A gluster client would like to read this file. Which brick 
will the file come from? In other words:

-        Will the file always be fetched from brick 1?

-        Will the file always be fetched from brick 2?

-        Will the file be fetched from brick 1 or 2 depending on the attempt? 
i.e. is there some load balancing where sometimes the file comes from brick 1 
and at other times the file will come from brick 2?

A given file will consistently be "read" from one of the N (in this case 2) 
replicas, as long as it holds a good copy of the file (that which does not need 
heal), even with client restart. We call it the "read child" of the file. Load 
balancing within a volume is done across different files wherein different 
files would have different but constant read children.

-Krutika
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