Pieter de Goeje wrote:
The fact that the limit is 86MB/sec (which is very low for a raid0 array)
makes me think the box suffers from sub optimal network performance during a
simple stream test like yours. This could be due to FreeBSD having a poor
network driver for your particular NIC or could be due to insufficient tuning
of the TCP parameters for this particular test.
Hi Pieter.
You are right about there being a number of possibilities, however:
*The same machine, which over the years has had a number of revisions of
freebsd on it (have buildworlded the thing from 7-> 7.1 -> 7.2 -> 8),
the performance was always roughly the same amongst the versions, I dont
agree with the possibility of the ftp server being 'slow' as I am the
only person who copies data to that machine, and the machine is always
under a very low (almost non existent) load.
* Network card is an Intel Pro 1000, on the server. This is a PCI card
(not pci-e), so I believe PCI bus bandwidth limitations may be
responsible for me not being able to achieve the maximum 100MB/s network
rate (as you mention that 86MB/s is slow for raid0)
* The intel network card driver on freebsd and linux are both fairly
rock solid and well written. I dont see it being an issue with NIC
drivers (they are not vastly different).
* Both OS's were stock standard installs, no jumbo frames enabled, no
fiddling with sysctl network values.
I am happy with 86MB/s anyway, It's a huge improvement of the 60MB/s
barrier I could never get past when that machine was running FreeBSD. To
get the rest of the speed, I'd probably have to install a pci-e card on
the server.
I do suspect personally that the ext4 filesystem is the reason for the
difference here, since ext4 has a number of features such as deferred
disk writes etc. Even deleting a large file off that raid array I can
see a difference, prior to reformatting, i deleted a 190GB file off the
raid, under UFS the delete took quite some time (well over 10 seconds),
under ext4 the deletion of the same size file took about 3 seconds.
But what I said with ext4 being faster then the aging UFS still rings
true in my mind, look at the recent Phoronix benchmarks for yourself and
see (10 pages of benchmarks).
http://www.phoronix.com/scan.php?page=article&item=freebsd8_benchmarks&num=1
(skip to page 7 of the benchmarks if you want to see the I/O stuff
relating to disk performance)
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