[Gluster-devel] Spurious disconnections / connectivity loss

Gordan Bobic gordan at bobich.net
Mon Feb 1 13:53:29 UTC 2010

Stephan von Krawczynski wrote:
> On Mon, 01 Feb 2010 11:10:16 +0000
> Gordan Bobic <gordan at bobich.net> wrote:
>> Stephan von Krawczynski wrote:
>>> On Sun, 31 Jan 2010 13:37:49 +0000
>>> Gordan Bobic <gordan at bobich.net> wrote:
>>>> Stephan von Krawczynski wrote:
>>>>> On Sun, 31 Jan 2010 00:29:55 +0000
>>>>> Gordan Bobic <gordan at bobich.net> wrote:
>>>>> Slightly offtopic I would like to ask if you, too, experienced glusterfs using
>>>>> a lot more bandwith than a comparable nfs connection on the server network
>>>>> side. It really looks a bit like a waste of resources to me...
>>>> I haven't noticed bandwidth going "missing", if that's what you mean. I 
>>>> do my replication server-side, so the server replicates the writes n-1 
>>>> times for n servers, and my cacti graphs are broadly in line with the 
>>>> bandwidth usage expected. If I disconnect all the mirrors except the 
>>>> server I'm connecting to,the bandwidth usage between the client and the 
>>>> server is similar to NFS.
>>>> What bandwidth "leakage" are you observing?
>>> My replication is done on client-side, because this is the only way to have it
>>> redundantly access the data if one server goes down (in theory).
>>> If I compare the bandwith used by glusterfs and the bandwith used by nfs for
>>> the same client it is obvious that nfs uses far less bandwith than glusterfs
>>> (comparing use of only one server of course). Interestingly incoming and
>>> outgoing server traffic is merely the same, whereas nfs has far less incoming
>>> traffic (server side), obviously because the client writes a lot less than it
>>> reads.
>> That's hardly unexpected. If you are using client-side replicate, I'd 
>> expect to see the bandwidth requirements multiply with the number of 
>> replicas. For all clustered configurations (not limited to glfs) I use a 
>> separate LAN for cluster communication to ensure best possible 
>> throughput/latencies, and specifically in case of glfs, I do server side 
>> replicate so that the replicate traffic gets offloaded to that private 
>> cluster LAN, so the bandwidth requirements to the clients can be kept 
>> down to sane levels.
> Sorry, Gordan, but that is completely unexpected. If I am using a client-side
> replicate with _one_ server there should be no more traffic expected than by
> using nfs. But in fact incoming traffic on server side jumped up to about the
> same level as outgoing. And that is obviously bogus.
> Please read "comparing use of only one server of course" above.

Sorry, I see what you mean now. Certainly, in a single server case that 
seems very wrong. I'd rather like to hear the developers' comments on this.


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