Re: strange discrepancy

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



Hi,

I've modified the .fio file according to the suggestions. Now, it
looks like this

[global]
ioengine=sync
direct=1
blocksize_range=1k-64k
directory=/mnt/drbd/private/
size=5120000000
runtime=7200

[seq_read]
rw=read
write_bw_log=iops_seq_read
write_lat_log=iops_seq_read
write_iops_log=iops_seq_read

[seq_write]
rw=write
write_bw_log=iops_seq_write
write_lat_log=iops_seq_write
write_iops_log=iops_seq_write

[random_read]
rw=randread
write_bw_log=iops_rand_read
write_lat_log=iops_rand_read
write_iops_log=iops_rand_read

[random_write]
rw=randwrite
write_bw_log=iops_rand_write
write_lat_log=iops_rand_write
write_iops_log=iops_rand_write

[random_rw]
rw=randrw
write_bw_log=iops_rand_randrw
write_lat_log=iops_rand_randrw
write_iops_log=iops_rand_randrw



Now, I'm getting much worst results (around 30 IOPS for random). I'm
wondering if the above config is the right approach for measur the
IOPS of this system?

As I written below this is a debian based box, using soft raid with
DRBD and my task is to tell what is the IOPS of this box


Any idea?

Thank you
Lastlo

On 21 February 2014 20:47, Pal, Laszlo <vlad@xxxxxxx> wrote:
> Thank you for your answer. I'm quite new in this, so I'm sure my parameters
> maybe not optimal.
>
> The system is a supermicro appliance running an ubuntu variant and using
> 2x7200 RPM disk in raid1 with DRBD
>
> The other box is a bit stronger and includes and adaptec raid controller
> 12x7200 RPM disk in RAID50 but also with DRBD
>
> The goal is to measure the IOPS of this two hardware running this software.
> Basically the IOPS values I've got with these parameters are very close to
> the average IOPS of a 7200 disk which is as far as I know arund 100
>
> I also put some comments inline, so if you can help me with same appropritae
> parameters for this scenario it would be great
>
> Thank you
> Laszlo
>
>
>
> On 21 February 2014 20:31, Carl Zwanzig <cpz@xxxxxxxxxx> wrote:
>>
>> > From: fio-owner@xxxxxxxxxxxxxxx [mailto:fio-owner@xxxxxxxxxxxxxxx] On
>> > Behalf Of Pal, Laszlo
>>
>> > Finally I've figured out how to use FIO :) now, I can measure several
>> > things, so I've started to get IOPS data for our hardware. The graphs
>> > looks good, however I can see a very strange discrepancy at seq_write
>> > part
>>
>> > [global]
>> > ioengine=libaio
>> Without iodepth >1, you'll effectively be doing synchronous i/o, so
>> there's no benefit to using libaio. If you're interested in throughput (not
>> latency), set iodepth to 512, which will likely be greater than whatever is
>> in the drive/controller/OS.
>>
>> > buffered=0
>> Don't need this if you specify-
>> > direct=1
>>
>>
>> > bs=4k
>> > blocksize_range=1k-64k
>>
>> AFAIK, blocksize_range will supersede bs. Also depending on the drive
>> (what type?), this can cause mis-aligned writes which massively slow the
>> overall process. I've mostly seen this with 4kn and 512e SSDs. You can
>> examine that by trying blockalign=4k.
>>
> it is normal 7200K disk
>>
>> > size=2048m
>> I usually use a runtime spec instead of size, and also set
>> fill_device=true.
>
>
>>
>>
>> [snip]
>>
>> >
>> > the results as the follows
>> (iops or MB/s?)
>
> these numbers from the IOPS log generated by fio
>>
>> > Random Read -- 86
>> > Random Write -- 77
>> > Sequential Read -- 2170
>> > Sequential Write -- 45
>>
>> > I have two questions again.
>> > The parameters above are good approach to determine IOPS for this
>> > system?
>> See above  :)
>>
>> > What can be the reason of the huge difference between Seq_read and
>> > Seq_write?
>>
>> Many things. First off, is this a block level test or is there a file
>> system involved? What drives? What controller? RAID?
>
> it is file system (ext3) soft raid + DRBD
>>
>>
>> z!
>>
>
--
To unsubscribe from this list: send the line "unsubscribe fio" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html




[Index of Archives]     [Linux Kernel]     [Linux SCSI]     [Linux IDE]     [Linux USB Devel]     [Video for Linux]     [Linux Audio Users]     [Yosemite News]     [Linux SCSI]

  Powered by Linux