[Gluster-users] is glusterfs DHT really distributed?

[Wei Dong]

Hi All,

I noticed a very weird phenomenon when I'm copying data (200KB image 
files) to our glusterfs storage.  When I run only run client, it copies 
roughly 20 files per second and as soon as I start a second client on 
another machine, the copy rate of the first client immediately degrade 
to 5 files per second.   When I stop the second client, the first client 
will immediately speed up to the original 20 files per second.  When I 
run 15 clients, the aggregate throughput is about 8 files per second, 
much worse than running only one client.  Neither CPU nor network is 
saturated.  My volume file is attached.  The servers are running on a 66 
node cluster and the clients are a 15-node cluster.

We have 33x2 servers and at most 15 separate machines, with each server 
serving < 0.5 clients on average.  I cannot think of a reason for a 
distributed system to behave like this.  There must be some kind of 
central access point.

- Wei





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