Gluster users - Jul 2015 - Read performances low compared to write (second try)

On Friday 10 July 2015 02:18 PM, Olivier JAVAUX wrote:
> Hello,
>
> I am evaluating GlusterFS and I have a question about read performance
compared to write performance.
> Release is 3.6.3-1 on SLES 11 SP 3.
> I have 12 storage nodes, configured in Ditributed-Replicated with 2
replicas.
> Network is 10 Gb ethernet.
> Filesystem used is xfs.
>
> When I am doing a simple test with dd bs=1M count=102400 (100 GB file with
blocksize=1M), I have good perfs when writing:
>    around 550 MB/s - 10 Gb network is the bottleneck (2 replicas)
> but when reading, performances are less good: 470 MB/s
> I read one replica and read performances on the node itself might be better
(around 800 MB/s)
> I tried several parameters:
>    performance.read-ahead: on
>    performance.read-ahead-page-count: 16
>    performance.io-thread-count: 32
>    performance.cache-size: 1GB
> I followed also performances hints for Linux kernel.
>
> Has somebody hints to increase these read performances?
>
Can you disable gluster's read-ahead translator and try again?

Additionally o/p of gluster volume info will be useful.

Regards,
Vijay

> Can you disable gluster's read-ahead translator and try again?
I am new to glusterfs.
To disable read-ahead xlator, I do:

gluster volume set <vol_name> performance.read-ahead off

??


> 
> Additionally o/p of gluster volume info will be useful.
# gluster volume info DFS

Volume Name: DFS
Type: Distributed-Replicate
Volume ID: 2cde4f9e-73c4-4555-a91c-d63873453b2a
Status: Started
Number of Bricks: 6 x 2 = 12
Transport-type: tcp
Bricks:
Brick1: DRS-MM-ADM-01-CLU:/glusterfs/data/brick
Brick2: DRS-MM-DWH-01-CLU:/glusterfs/data/brick
Brick3: DRS-MM-PRO-01-CLU:/glusterfs/data/brick
Brick4: DRS-MM-PRO-02-CLU:/glusterfs/data/brick
Brick5: DRS-MM-PRO-03-CLU:/glusterfs/data/brick
Brick6: DRS-MM-PRO-04-CLU:/glusterfs/data/brick
Brick7: DRS-MM-PRO-05-CLU:/glusterfs/data/brick
Brick8: DRS-MM-PRO-06-CLU:/glusterfs/data/brick
Brick9: DRS-MM-PRO-07-CLU:/glusterfs/data/brick
Brick10: DRS-MM-PRO-08-CLU:/glusterfs/data/brick
Brick11: DRS-MM-PRO-09-CLU:/glusterfs/data/brick
Brick12: DRS-MM-PRO-10-CLU:/glusterfs/data/brick
Options Reconfigured:
performance.read-ahead: on
performance.read-ahead-page-count: 16
performance.io-thread-count: 32
performance.cache-size: 1GB

Thanks for your help

Best regards,

	Olivier