[Gluster-users] Basic gluster questions

[John Hanks]

The culprit appears to be my source NFS server, looks like some of
it's RAID sets decided they needed to rebuild at about the same time I
was doing my testing. One should never assume that because something
worked well yesterday it will work well today, will retry things with
a different source that works as expected.

jbh

On Wed, Jun 1, 2011 at 12:44 AM, Pavan <tcp at gluster.com> wrote:
> On Tuesday 31 May 2011 11:01 PM, John Hanks wrote:
>> Hi,
>>
>> I'm setting up gluster for the first time and have a single server
>> with two bricks set up for testing:
>>
>> [root at filer-jdn1bp1 etc]# gluster volume info
>>
>> Volume Name: projects
>> Type: Distribute
>> Status: Started
>> Number of Bricks: 2
>> Transport-type: tcp
>> Bricks:
>> Brick1: filer-jdn1bp1:/glusterfs/0.0
>> Brick2: filer-jdn1bp1:/glusterfs/0.1
>> Options Reconfigured:
>> nfs.disable: on
>>
>> Mounting this volume on the server or on a separate client over a 10
>> Gbps link is working, but I'm seeing weird performance patterns. If I
>> do this:
>>
>> time sh -c "dd if=/dev/zero of=./testfile count=32768 bs=1M; sync"
>>
>> in the glusterfs mounted directory on either client I see rates of
>> ~250 MB/s but if I try to copy files onto the volume with either rsync
>> or cpio pass-thru, the rates drop to<  10 MB/s. The directories I am
>> attempting to copy are mostly large files (>  10 GB) and as I watch
>> cpu, network and disk i/o stats, nothing seems to be stressed or
>> blocked, it's just slow.
>
> You cannot just look at the cpu, network, io stats and conclude that
> things are fine. You will have to look at these values in comparison
> with dthe dd case where things work according to your expectation.
>
> When you say you are "rsync'ing to the volume", *from where* do you rsync?
>
> Pavan
>
>>
>> I've been searching for documentation on how to possibly tune this or
>> track down the bottleneck but not having much luck. Most things that
>> turn up in searches seem to apply to older gluster versions and the
>> 3.2 documentation is pretty sparse with respect to tuning things.
>>
>> Any suggestions for what I am doing wrong with this setup or any
>> pointers to documentation on how to troubleshoot/tune this would be
>> appreciated, especially any "intro for dummies" type docs that could
>> fill in the big gaps in my understanding of how gluster works. I'm
>> open to an RTFM reply, just haven't found the right manual yet myself
>> and would appreciate a pointer :)
>>
>> Thanks,
>>
>> jbh
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>
>