Chelsio T420 CR /SO

[ekke]

Would I as a home user have use for the extra memory in the CR version ? Or should I go with the cheaper CR-SO version?

The card will sit in my FreeNAS server that servers as many sessions (1Gbit link) and my media/backup etc

 

[izx]

The -CR supports hardware offload of up to 32,768 connections; the no-memory -SO-CR supports 128 connections. Assuming you will exceed 128 concurrent connections (which you will on a seedbox), it's a no-brainer.

 

[Keljian]

Not sure I would want my seed box and my backup box to be in the same machine...

 

[ekke]

Not sure I would want my seed box and my backup box to be in the same machine...

Why? It's a homeserver. Consolidating is a must due to space limitations.

 

[Keljian]

Security, in a nutshell

 

[ekke]

Well I would believe it's more secure to run rtorrent in a jail than other alternatives like µtorrent in windows. Sure there are flaws in rtorrent but I think general browsing is a bigger threat.

 

[MiniKnight]

Well I would believe it's more secure to run rtorrent in a jail than other alternatives like µtorrent in windows. Sure there are flaws in rtorrent but I think general browsing is a bigger threat.

Jail = good.

Biggest security issue is running a torrent seed box anyway.

 

[Fritz]

What are you seeding?

 

[ekke]

flowers

 

[Fritz]

LOL, why did I ask.

 

[sth]

now we got to the bottom of some real world practical differences between the CR and SO-CR, I'd be interested to hear re T-420 vs T-520 too.

 

[izx]

I'd be interested to hear re T-420 vs T-520 too.

For SOHO scenarios, no practical difference. T520 is PCIe 3.0 x8 (64 Gbps theoretical peak) while T420 is PCIe 2.0 x8 (32 Gbps theoretical peak). Both are limited to 2x 10Gbps line rate...

 

[ekke]

I was looking at the specs before, dont know how I could have missed it

Cr so
Memory free & up to 128 connec-tions for offload functionalities Full TCP offload

T420-SO-CR | Chelsio Communications



Cr
Supports Up to 1M connections  Full TCP & UDP offload

T420-CR 10GbE NIC Terminator 4 adapters Product Description | Chelsio Communications


T520
Got more fearures

T520-CR | Chelsio Communications

 

[RTM]

When talking offload, it is usually relevant to discuss support, because as far as I know these things are often disabled.
Are there any known applications or platforms that are known to use these features? (for now, just talking about Chelsio)
If so what is the performance gain?

 

[izx]

When talking offload, it is usually relevant to discuss support, because as far as I know these things are often disabled.
Are there any known applications or platforms that are known to use these features? (for now, just talking about Chelsio) If so what is the performance gain?

See the right sidebar on page 2 of the T420-CR product brief for provided offloads.
This wiki article on TCP offload engine is a good introduction to the basics of offloading for 10GE adapters and provides a general rule of thumb for "performance gained" by freeing up CPU cycles.

 

[ekke]

Wiki said Linux doesn't support offloading, you need to patch it for that. I couldnt find anything about freenas tho.

 

[izx]

Wiki said Linux doesn't support offloading, you need to patch it for that. I couldnt find anything about freenas tho.

Quoting from the FreeBSD 9.3.3 man page on the Chelsio T4 driver (cxgbe):

The cxgbe driver provides support for PCI Express Ethernet adapters based on the Chelsio Terminator 4 and Terminator 5 ASICs (T4 and T5). The driver supports Jumbo Frames, Transmit/Receive checksum offload, TCP segmentation offload (TSO), Large Receive Offload (LRO), VLAN tag insertion/extraction, VLAN checksum offload, VLAN TSO, and Receive Side Steering (RSS).

Chelsio supplies their own Linux drivers which provide full TOE. Enterprise hardware isn't always plug-and-play on Linux, and patching/recompiling kernel modules is par for the course.