Re: Disabling gluster cache

[Prashanth kumar N <prashanth.kumar.n@xxxxxxxxx>]

Hi,

Can anyone please provide your inputs on the issue?

-Prashanth

On Thu, Dec 17, 2015 at 11:33 AM, Prashanth kumar N <prashanth.kumar.n@xxxxxxxxx> wrote:

Hi,

One of my gluster deployment requires to completely disable Gluster caching and put in proprietary caching logic. Setup is as follows:

- PCI flash will be used as flash

- Two node connected using 40GB Melanox cards

- Gluster version 3.7.6

With fresh installation of Gluster, using fio with libgapi with bs=1M/4M, seq_write i am able to achieve speeds up to 2.4GB/s from user point of view. When i check the raw flash speed, seeing bandwidth of 1.1GB/s but flash is capable of getting speeds of 1.5GB/s. 

Before putting in our own cache, i disabled Gluster  caching by disabling below options and measured fio speed 

gluster vol set $vol_name performance.io-cache off

gluster vol set $vol_name performance.write-behind off

gluster vol set $vol_name performance.flush-behind off

service glusterd restart

[ $vol_name was my name name passed in shell script ]

With the above parameters disabled, i was drop in fio speed ( as expected ) to around 1.4GB/s but raw flash speed measured was around 250-350MB/s using iostat. This shows that Gluster caching might not be completely disabled or i am missing some piece of information.

Please provide your valuable inputs if any other settings need to be disabled.

-Prashanth

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