11-STABLE vs 11.0-RELENG test

Andriy Gapon avg at FreeBSD.org
Tue Dec 6 17:14:24 UTC 2016

On 06/12/2016 18:17, Alex Tutubalin wrote:
> Followup, same box as in 1st message, but with different HBA and 5 HDD:
> Summary:
>  1) read speed depends on 'on-disk' data, not by code used while read.
>  2) FreeBSD 11.0-releng (svn up today) creates 'fast' big files (420+ Mb/s read
> speed)
>  3)  FreeBSD 11-STABLE creates 'slow' big files. (~200  Mb/s)
>  4) zfs send slow-dataset | zfs recv   (under 11.0-releng) creates
> 'intermediate' files (320Mb/s)
>  5) file copy slow-file ... (under 11.0-releng) creates fast copy (400+Mb/s)
> So, ZFS write code in 11-STABLE looks broken.
> Here detailed log of my tests:
> Box: Intel i5-2400, 16Gb of RAM, Adaptec 5805, 5x4Tb drives (HGST NAS drives) in
> JBOD, merged in RAIDZ2, enough free space:
> $ zpool list
> zdata    18,1T  5,11T  13,0T         -     9%    28%  1.00x  ONLINE -

That's an interesting observation.

Could you please try starting with a freshly created pool and writing some data?
I wonder if 'zpool list -v' will show any significant differences between
different FreeBSD versions?
Another thing to check would be 'zdb -mm' but it could be very large.  However,
a difference should be sufficiently small as most of the space would remain unused.

And, just in case, please compare 'zpool get all' and 'zfs get all' between
those two versions.

Andriy Gapon

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