[Gluster-users] is glusterfs DHT really distributed?
wdong.pku at gmail.com
Mon Sep 28 14:51:20 UTC 2009
Your reply makes all sense to me. I remember that auto-heal happens at
file reading; doest that mean opening a file for read is also a global
operation? Do you mean that there's no other way of copying 30 million
files to our 66-node glusterfs cluster for parallel processing other
than waiting for half a month? Can I somehow disable self-heal and get
Things turn out to be too bad for me.
Mark Mielke wrote:
> On 09/28/2009 10:35 AM, Wei Dong wrote:
>> 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.
> Although there is probably room for the GlusterFS folk to optimize...
> You should consider directory write operations to involve the whole
> cluster. Creating a file is a directory write operation. Think of how
> it might have to do self-heal across the cluster, make sure the name
> is right and not already in use across the cluster, and such things.
> Once you get to reads and writes for a particular file, it should be
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