Re: Aggregated results too high when using multiple servers via "client" command

You are absolutely right. Lots of details missing indeed…

fio-3.36 on Ubuntu 24.04.2 LTS

Command: 
fio --client=configs/host.list fio-configs/test.job --output=test.output --output-format=json

cat test.job:
[global]
filename=/mnt/benchmark/testfile.dat
group_reporting
write_bw_log=aggregated

[Full Write]
size=25G
bs=512K
rw=write
ioengine=libaio
direct=1
time_based
runtime=60s

cat host.list
10.100.12.51
10.100.12.52
10.100.12.53
10.100.12.54

My target is a NAS device mounted via CIFS/SMB under /mnt/benchmark/
I played around with write_bw_log=aggregated and group_reporting, but in the end the summarized Bandwidth  is always higher than my target device overall performance.


> Am 02.05.2025 um 09:23 schrieb Sitsofe Wheeler <[email protected]>:
> 
> Hello René,
> 
> On Wed, 30 Apr 2025 at 08:50, René Weber <[email protected]> wrote:
> I am trying to do a benchmark from multiple clients in order to test the performance of a NAS device.
> When running the test each of the clients reports a performance of ~950MB/s. The summarized performance in the log shows 4x950MB/s though the NAS device only supports (and shows) a maximum bandwith of 950 MB/s in total. To my understanding, the servers I am adressing via „client=host.list“ should generate load in parallel which should then reduce each stream to the maximum bandwith supported by the NAS divided by the number of clients… but somehow each client reports the maximum bandwith oft he target and the summary therfor is wrong. I tried group_reporting and various other command without success.
> Any advice here for a newbie?
> 
> Could you post the full command line and job files you are using? Generally the information requested in https://github.com/axboe/fio/blob/master/REPORTING-BUGS is always helpful!
> 
> -- 
> Sitsofe