XigmaNAS

Hi,

i have a massive Speed difference with the same Pool on different Systems.
I created the Pool on Nas4Free, 2x Hitachi 3TB -> mirror
I tested the Write/Read with DD:

dd if=/dev/zero of=/mnt/raid1-hd/Data/test.dat bs=2M count=1400
dd if=/mnt/raid1-hd/Data/test.dat of=/dev/null bs=2M

Between write and read Test i rebooted the System and I've done the Tests on each System multiple times:

Nas4Free 9.1.0.1 - Sandstorm (Revision 804)
Write: ~103 MB/Sec
Read: ~105 MB /Sec

FreeNAS 9.1
Write: ~105 MB/Sec
Read: ~155 MB /Sec

Debian Wheezy - ZFS on Linux:
Write: ~105 MB/Sec
Read: ~160 MB /Sec

The Write Speed is almost equal on the Systems. But why is the Read Speed on Nas4Free so slow compared with the Others?
I hvae alredeady tested "kernel tune", but no Difference.

Any Ideas?

Did you enable prefetch in zfskerntune? This seems like the likely cause. If you system has >4GB of RAM the other systems will enable it by default but NAS4Free has is explicitly disabled.

The following shows you how to check.

http://n4f.siftusystems.com/index.php/2 ... it-in-gui/

And here is some performance with it enabled and disabled.

http://n4f.siftusystems.com/index.php/2 ... -prefetch/

Hope that helps.

That's it!

vfs.zfs.prefetch_disable="0"

is the Solution.


I had taken the tuning Parameters from viewtopic.php?f=71&t=1278&p=10011&hilit=tune#p21974 an there is written vfs.zfs.prefetch_disable="1" !?


The DD Speed is ok now, similar to Freenas and ZoL.
But my AFP Speed is the same as befor, see Post viewtopic.php?f=26&t=4736
Also any Ideas?

Just curious, how stable is ZFS on Linux?

Before check and compare disk speed with dd pls check disk performance with and see output for Transfer rates.
See differences between outside, middle, inside

See my last Post, i had written that the speed is ok now with:

vfs.zfs.prefetch_disable="0"

Now I have only a Problem with AFP Speed -> viewtopic.php?f=26&t=4736