[Gluster-users] stripped volume in 3.4.0qa5 with horrible read performance

[John Mark Walker]

Please file a bug. There might be time to fix read performance before the 1st beta release. 

-JM 

----- Original Message -----

> Dear folks,

> I've been tried to use replicated stripped volumes with 3.3.
> unsuccessfully due to
> https://bugzilla.redhat.com/show_bug.cgi?id=861423 and I then
> proceed to try 3.4.0qa5. I then find out that the bug was solved and
> I could use replicated stripped volume with the new version.
> Amazingly, write performance was quite astonishing.

> The problem I'm facing now is in the read process: It's horribly
> slow. When I open a file to edit using the gluster native client, it
> takes a few seconds and sometimes I got an error refering to file
> has been modified while I was editing it. There's a ruby application
> reading the files and I got continuously timeout errors.

> I'm using 4 bricks with Centos 6.3 with the following structure:
> Type: Striped-Replicate
> Volume ID: 23dbb8dd-5cb3-4c71-9702-7c16ee9a3b3b
> Status: Started
> Number of Bricks: 1 x 2 x 2 = 4
> Transport-type: tcp
> Bricks:
> Brick1: 10.0.51.31:/gfs
> Brick2: 10.0.51.32:/gfs
> Brick3: 10.0.51.33:/gfs
> Brick4: 10.0.51.34:/gfs
> Options Reconfigured:
> performance.quick-read: on
> performance.io-thread-count: 32
> performance.cache-max-file-size: 128MB
> performance.cache-size: 256MB
> performance.io-cache: on
> cluster.stripe-block-size: 2MB
> nfs.disable: on

> I started profiling and found out one node with absurd latency
> figures. I stopped the node and the problem moved to another brick:
> %-latency Avg-latency Min-Latency Max-Latency No. of calls Fop
> --------- ----------- ----------- ----------- ------------ ----
> 99.94 551292.41 us 10.00 us 1996709.00 us 361 FINODELK

> Could anyone provide some information how to debug this problem?
> Currently the volume is not usable due to the horrible delay.

> Thank you very much in advance,
> Samuel.

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