The message <(E-Mail Removed)>
from Char Jackson <(E-Mail Removed)> contains these words:
> On Mon, 15 Feb 2010 20:19:47 -0500, Alan Browne
> <(E-Mail Removed)> wrote:
> >Set up a gigabit switch and a new NAS file server.
> >
> >New CAT 6 cables.
> >
> >Set the NAS to hard 1000 Mb/s.
> >Checked the Mac ethernet was auto con. to 1000 Mb/s.
> >
> >All I get as a transfer speed is, top, 20 MB/s (160 Mb/s).
> >
> >I returned the switch, and ordered a different one (a D-Link) online
> >(along with a gigabit ethernet PCI card for the PC). Maybe it will be a
> >bit better.
> >
> >But kinda disappointed in the throughput. I thought I'd be hitting 500
> >Mb/s at least (60 MB/s). (Mac has serial ATA 3 Gb/s, so does the NAS).
> >
> >I'll see how well Mac->PC flows in RAMDisk to RAMDisk - but I doubt I'm
> >going to see a huge improvement. Also need to try jumbo frames for a
> >few more %.
> >
> ><sigh>
> I'm running bottom of the barrel TrendNet Gigabit NIC's that I got on
> sale at Newegg for $7 each a couple of years ago, and the best
> throughput I've seen is about 370 Mbps. My Gigabit D-Link switch is
> the DGS-2208. I've been told I could see a 2x improvement in
> throughput if I had better NICs, but these are fine for me. Anyway,
> make sure your duplex settings are set correctly, drivers updated,
> etc.
I didn't see Alan's original posting (his domain must in my killfile
list) but, ime, this sort of shortfall on expectations with Gbit
ethernet is pretty normal with consumer grade PC hardware (although, in
his case, the 20MB/s transfer speeds are particularly disappointing).
As you've said, it's particularly important to experiment with the
advanced settings on the Gbit ethernet adapter. Usually, enabling jumbo
frames makes a noticable improvement (in my case, it made transfer
speeds slightly worse with the current FreeNAS hardware since the LAN
driver seems to have a bug which prevents the jumbo frame option from
actually being applied).
A few years ago, this, now almost 6 year old, setup with win2kSP4
managed speeds of 40MB/s (reading and writing) into a "Bleeding Edge'
3GHz clocked P4 system running winXP. The win2k box has a Jetway V600DAP
via chipset socket A motherboard with an XP2500+ Barton Cored CPU and a
Netgear GA311 NIC plugged into a PCI slot (actually a "Realtek
RTL8169/8110 Family Gigabit Ethernet NIC" according device manager - the
on-board NIC now being disabled in the BIOS).
At that time, I had jumbo frames enabled on both machines (afaicr, it
gave something like a 50% boost in speed). When I upgraded the FreeNAS
box about a year ago with a cheap Asrock MoBo with 4 sata ports and
built in Gbit ethernet, I still had to plug another GA311 card in since
the then current version of FreeNAS lacked driver support for the
on-board NIC. With jumbo frames enabled, I think I was seeing somewhere
in the region of 25 to 30MB/s transfers (I had 4 1TB Samsung drives in
the server).
Eventually, a few months after that upgrade, the current version of
FreeNAS became available which allowed me to remove the GA311 adapter
and use the on-board adapter. As I've already mentioned, there is an
issue with jumbo frame support and it turned out that my optimum
performance setting on the win2k box was with jumbo frames disabled (and
it still is).
I've since done a bit more tweaking of cpu multiplier settings[1] (it
seems you need stupendous amounts of cpu 'grunt' to service the Gbit
ethernet adapter compared to the actual file server needs) and now see
35MB/s or better between the win2k box and the server. This, when the
transfer isn't fighting the effects of file fragmentation on the client,
equates to a tad over the magic 2GB per minute mark. For the time being,
I'm happy with this since it isn't so far behind the disk to disk
transfer speeds within the win2k box itself.
Although the benefit of a Gbit network appears to be wasted with most
PC kit, even a twofold boost is a welcome improvement over the
limitations of Fast ethernet. And, it's worth bearing in mind that
you're running transfers over a network that has plenty of capacity to
spare, not only to allow PC hardware/driver upgrades to offer
performance gains but also to allow traffic from other connected PCs to
proceed without impinging on each other's performance.
[1] I'd fitted the cheapest AM2 socket CPU I could get my hands on, a
Semperon LE-1250 rated for a clock speed (actual) of 2.2GH and had
originally tried the slowest 100MHz FSB setting of 800MHz (200MHz DDR
FSB and x4 multiplier) along with a Vcore voltage reduced to 0.8v (from
the 1.35v setting this cpu normally requires) on the basis that file
serving requires but a fraction of the obscenely huge amount of cpu
grunt available from this processor at its rated speed.
Unfortunately, I hadn't counted on the out of all proportionate demands
of the Gbit ethernet adapter (add in PCI or on-board) and had to use a
faster setting to improve the Gbit performance. I chose a x6 multiplier
with the standard 100MHz (200MHz DDR) FSB to give me a 1.2GHz cpu clock
(along with a Vcore boost to 0.95v) as the optimum trade off between
power consumption and speed gain. Going all the way to 2.2GHz would only
give another 2 or 3 percent improvement for the extra 10 to 15 watts
consumption this entailed.
If a later version of FreeNAS becomes available with the jumbo frames
issue fixed, I might be able to see a further boost in Gbit performance
(possibly by as much as another 50%) making 3GB per minute transfers a
distinct possibility.
HTH & HAND
--
Regards, John.
Please remove the "ohggcyht" before replying.
The address has been munged to reject Spam-bots.
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