[Gluster-users] Disabling gluster cache

[Prashanth kumar N]

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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