Testing write master and multiple read clients on NFS share

[Michael Weinrich <micxer@micxer.de>]

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Hi,

in my company we have some sort of database that operates on bit lists 
read directly from the files on the hard disk. While this is ok if you 
have an SSD in your server it gets tricky to keep performance up when 
using an NFS share.

While I was trying to assess different solutions I stumbled upon fio and 
was happy to see that it can also run in client-server-mode. So I was 
trying to emulate the following scenario:

- 1 node that takes care of updating the bit lists in the db files,
   nothing else
- 5 nodes that only read from those files and respond to queries, 
hopefully leveraging the local filesystem or NFS client cache

I read through the HOWTO and tried to pick the options that should 
simulate the scenario as best as possible. This is what I came up with:

[global]
ioengine=sync
iodepth=1
size=100%
io_size=4g
filesize=4g
blocksize=64k
direct=0
numjobs=4
directory=/mnt/nfs
filename_format=index.$filenum
fadvise_hint=0
lockfile=readwrite
randrepeat=1
nrfiles=8
openfiles=4
runtime=120
ramp_time=10
blocksize=64k
file_service_type=random:8
overwrite=1
fsync_on_close=1
random_distribution=zipf:0.6
norandommap
file_append=0
rate=1m

[reader]
rw=randread

[writer]
rw=randrw
rwmixwrite=80


Is this a viable approach or is this scenario not really testable with fio?


Thanks,
Michael


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