Re: Repeat given pattern with buffer_compress_percentage

[Jens Axboe <axboe@kernel.dk>]

On 12/05/2014 12:25 AM, Karthick Srinivasachary wrote:
> Hi Jens,
>
> Awesome.. Thanks for the fix..!
> With compress_percentage 80 or more, fio verify is failing. I don't
> think there any issue with storage in my test environment. Do you
> think we have a bug here. Complete command and output below.
>
> /usr/local/bin/fio --name=global --ioengine=libaio --bsrange=16k-64k
> --rw=randrw --iodepth=16 --direct=1 --verify=md5 --name=job0
> --size=100m --filename=/fio/fio.dat --rw=randrw --rate=20m
> --buffer_compress_percentage=80 --refill_buffers --buffer_pattern=123
> --verify_dump=1

You can't do a random read/write test, it'll fail on the reads that have 
not been populated. It might sometimes work if the file had been laid 
out prior with the right contents, but generally you cannot depend upon 
it. You want to do just --rw=randwrite and then the verify phase will 
take place after the writes are done, verifying those.

Try and delete fio.dat prior to running this job, and it should fail 
consistently with or without buffer_compress_percentage.

-- 
Jens Axboe