I'm still missing something. I can check on the monitor to see that the running 
config on the cluster has rbd cache = false

[root@essperf13 ceph]# ceph --admin-daemon 
/var/run/ceph/ceph-mon.essperf13.asok config show | grep rbd
  "debug_rbd": "0\/5",
  "rbd_cache": "false",

Since rbd caching is a client setting I've added the following to the rbd 
client /etc/ceph/ceph.conf

[global]
log file = /var/log/ceph/rbd.log
rbd cache = false
rbd readahead max bytes = 0  "should be" disabled if rbd cache = false, but I'm 
paranoid 

 [client]
admin socket = /var/run/ceph/rbd-$pid.asok

I never see a rbd*asok file in /var/run/ceph. I started the rbd driver on the 
client without /var/run/ceph directory and then see:
2015-02-02 14:40:30.254509 7f81888257c0 -1 asok(0x7f8189182390) 
AdminSocketConfigObs::init: failed: AdminSocket::bind_and_listen: failed to 
bind the UNIX domain socket to '/var/run/ceph/rbd-1716.asok': (2) No such file 
or directory

When I attempt to map the rbd image to the client device with "rbd map". Once I 
create /var/run/ceph these messages don't occur. So it appears that the admin 
sockets are being created, but only for the duration of the command. 

I still see the effects of rbd caching if I run fio/vdbench with 4K random 
reads, but I have not been able to create a persistant rbd admin socket so that 
I can dump the running configuration and/or change it at run time.

Any ideas on what I've overlooked?

Any pointers to documentation on the [client] section of ceph.conf? rbd admin 
sockets? Nothing at ceph.com/docs on either topic.
Thanks,
Bruce

-----Original Message-----
From: Mykola Golub [mailto:to.my.troc...@gmail.com] 
Sent: Sunday, February 01, 2015 1:24 PM
To: Udo Lembke
Cc: Bruce McFarland; ceph-us...@ceph.com; Prashanth Nednoor
Subject: Re: [ceph-users] RBD caching on 4K reads???

On Fri, Jan 30, 2015 at 10:09:32PM +0100, Udo Lembke wrote:
> Hi Bruce,
> you can also look on the mon, like
> ceph --admin-daemon /var/run/ceph/ceph-mon.b.asok config show | grep 
> cache

rbd cache is a client setting, so you have to check this connecting to the 
client admin socket. Its location is defined in ceph.conf, [client] section, 
"admin socket" parameter.

--
Mykola Golub
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