[Gluster-users] NFS versus Fuse file locking problem (NFS works, fuse doesn't...)

[Krist van Besien]

Hi
This is gluster 3.8.4. Volume options are out of the box. Sharding is off
(and I don't think enabling it would matter)

I haven't done much performance tuning. For one thing, using a simple
script that just creates files I can easily flood the network, so I don't
expect a performance issue.

The problem we see is that after a certain time the fuse clients completely
stop accepting writes. Something is preventing the application to write
after a while.
We see this on the fuse client, but not when we use nfs. So the question I
am interested in seeing an answer too is in what way is nfs different from
fuse that could cause this.

My suspicion is it is locking related.

Krist


On 24 August 2017 at 14:36, Everton Brogliatto <brogliatto at gmail.com> wrote:

> Hi Krist,
>
> What are your volume options on that setup? Have you tried tuning it for
> the kind of workload and files size you have?
>
> I would definitely do some tests with feature.shard=on/off first. If shard
> is on, try playing with features.shard-block-size.
> Do you have jumbo frames (MTU=9000) enabled across the switch and nodes?
> if you have concurrent clients writing/reading, it could be beneficial to
> increase the number of client and server threads as well, try setting
> higher values for client.event-threads and server.event-threads.
>
> Best regards,
> Everton Brogliatto
>
>
>
> On Thu, Aug 24, 2017 at 7:48 PM, Krist van Besien <krist at redhat.com>
> wrote:
>
>> Hi all,
>>
>> I usualy advise clients to use the native client if at all possible, as
>> it is very robust. But I am running in to problems here.
>>
>> In this case the gluster system is used to store video streams. Basicaly
>> the setup is the following:
>> - A gluster cluster of 3 nodes, with ample storage. They export several
>> volumes.
>> - The network is 10GB, switched.
>> - A "recording server" which subscribes to multi cast video streams, and
>> records them to disk. The recorder writes the streams in 10s blocks, so
>> when it is for example recording 50 streams it is creating 5 files a
>> second, each about 5M. it uses a write-then-rename process.
>>
>> I simulated that with a small script, that wrote 5M files and renamed
>> them as fast as it could, and could easily create around 100 files/s (which
>> abouts saturates the network). So I think the cluster is up to the task.
>>
>> However if we try the actualy workload we run in to trouble. Running the
>> recorder software we can gradually ramp up the number of streams it records
>> (and thus the number of files it creates), and at arou d 50 streams the
>> recorder eventually stops writing files. According to the programmers that
>> wrote it, it appears that it can no longer get the needed locks¸ and as a
>> result just stops writing.
>>
>> We decided to test using the NFS client as well, and there the problem
>> does not exist. But again, I (and the customer) would prefer not to use
>> NFS, but use the native client in stead.
>>
>> So if the problem is file locking, and the problem exists with the native
>> client, and not using NFS, what could be the cause?
>>
>> In what way do locking differ between the two different file systems,
>> between NFS and Fuse, and how can the programmers work around any issues
>> the fuse client might be causing?
>>
>> This video stream software is a bespoke solution, developped in house and
>> it is thus possible to change the way it handles files so it works with the
>> native client, but the programmers are looking at me for guidance.
>>
>> Any suggestions?
>>
>> Krist
>>
>>
>>
>>
>> --
>> Vriendelijke Groet |  Best Regards | Freundliche Grüße | Cordialement
>> ------------------------------
>>
>> Krist van Besien
>>
>> senior architect, RHCE, RHCSA Open Stack
>>
>> Red Hat Red Hat Switzerland S.A. <https://www.redhat.com>
>>
>> krist at redhat.com    M: +41-79-5936260
>> <https://red.ht/sig>
>> TRIED. TESTED. TRUSTED. <https://redhat.com/trusted>
>>
>> _______________________________________________
>> Gluster-users mailing list
>> Gluster-users at gluster.org
>> http://lists.gluster.org/mailman/listinfo/gluster-users
>>
>
>


-- 
Vriendelijke Groet |  Best Regards | Freundliche Grüße | Cordialement
------------------------------

Krist van Besien

senior architect, RHCE, RHCSA Open Stack

Red Hat Red Hat Switzerland S.A. <https://www.redhat.com>

krist at redhat.com    M: +41-79-5936260
<https://red.ht/sig>
TRIED. TESTED. TRUSTED. <https://redhat.com/trusted>
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