Super User is a question and answer site for computer enthusiasts and power users. It's 100% free, no registration required.

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I am looking between two options, a pair of Emulex LPe1150-E cards or a pair of Dell XR997 cards. What I'm looking to do:

  1. I have a RAID6 array with an NTFS volume on an Areca card.
  2. I have my i5-2500k computer in my room.
  3. My files I want far away (~30m wire path) in a rack case.
  4. I won't settle for 1 gigabit speeds, nor do I want to mix traffic on my network, so I want a dedicated link.
  5. One huge single volume showing up as a drive in Windows 7 x64 Ultimate.
  6. Server will be some Linux distro. It will be an i7-970.

Would the Dell NIC with iSCSI be really too taxing on CPU cycles? This seems like the easiest route, as far as setting it up, and I know it will give me my file, but maybe really taxing on the hardware. I am really clueless about the alternate route, with Fibre Channel. Can that accomplish what I want? I don't get where people get their knowledge. Is it handed down through the IT generations like secret society-type stuff? I only ask because I can't seem to find any information on this. I have no problems understanding hardware, it's just the software side of things that menace my brain. I am racked because the cost of both is pretty equal, but I can't get into adventurism in seeing if one thing works, but then it doesn't. I don't pull much of an income, so I can't just go buying hardware left and right to play around with. I need a solution that I know will work.

share|improve this question
up vote 1 down vote accepted

If the NIC has ToE (TCP Offload Engine), it greatly reduces the amount of processing power required by the CPU. I would say that at anything > 1Gbps speed it is almost mandatory.

The difference between Fibre Channel and iSCSI is that iSCSI runs over IP, which is a lossy protocol (i.e. packets are not guaranteed to arrive in the correct order, or even at all), where as FC is almost the exact opposite.

Personally, I would go the iSCSI route. It's more bang for your buck, and at the end of the day you have a 10Gbps network. FC cannot be used for TCP/IP communications, whereas 10GbE can. Also, you can then just use the Windows iSCSI initator to make the volume show up on your other PC.

FC is rarely seen outside of large datacenters. But it's important to note that just because you're using 10GbE, doesn't mean you can't use fibre. You can (and may very well want to, if it's over 30 meters) use Fiber Optic cables to run your network between locations. That XR997 is a copper (CAT6 with RJ45) card though, so you would need to find two 10GbE fibre cards in order to go that path.

As for where do we get this info from? You're right, there's no real repository on where to learn this stuff, and yes, a lot of it is handed down when there's a need for it. Often by people asking questions just like yours. Or, if you're a business, you would go to Dell/HP/EMC/etc, explain your situation, and then they would hold your hand through the decision making process.

share|improve this answer
The link is going to be for storage data only. I will get my IP traffic from my regular ethernet link/network. For the reason being I don't want to spend money on a crazy switch just to integrate that into my network. I'm the only one going to be using this array. From what I see iSCSI is pretty taxing, even with a NIC with a processor, because the NIC still doesn't process the SCSI blocks from the IP packets, and the CPU has to in software. The actual iSCSI HBAs seem to not be anywhere in my price range. I'd rather go fiber and take a hit down to 4 Gbps if it means almost no CPU usage. – timramich Feb 2 '12 at 0:18
@timramich - sounds like you've got it all sorted out then. FC isn't really designed to be used in a P2P environment, but as Journeyman pointed out, apparently it can be done. As someone who runs a 10GbE iSCSI network in a virtualisation and heavy SQL environment, I can attest that it's almost impossible to staurate 10Gbps as you need a LOT of traditional SAS disks (like, a hundred or so, or if you're using SSD at least a dozen or so) to even come close. So I doubt that the amount of load you'll be putting the disks under will affect your processor too much. And if it really gets bad, – Mark Henderson Feb 2 '12 at 1:18
it may more long-term effective to get a dual-socket workstation and have 2x octo-core processors or the like. – Mark Henderson Feb 2 '12 at 1:19
I will doing a lot of throughput, not really I/Os. I'm going to have 16 hard drives in a RAID-6 array at some point, and when SSDs are affordable in like 5 years, I will switch over to them. I have 6 in there now and I can easily hit 300 MB/sec with sequential reads. That's already 2.4 Gbps. I think a 4 Gbps link will be fine, I just can't find any info about serving up a disk in Linux with this card I'm looking at. I suspect getting it as a disk in Windows will be fairly straightforward. – timramich Feb 2 '12 at 1:24
My FC experience is fairly limited, but I believe it shows up as a storage adapter, and once you configure it, the disks themselves just appear in the OS, like a hot-plugged drive. However, as for "fairly straight-forward", that's not something I would generally use to describe any sort of storage network :) Anyway hope you have success with it. – Mark Henderson Feb 2 '12 at 2:08

Generally most people learn about such stuff at work or through certifications - not through secret handshakes.

I'll start off with 10 gig-e. Most decent network cards (that is to say anything better than consumer level cards) have their own internal processor (the dells seem to have one that is powerful enough to need its own fan), and are unlikely to trouble the main processor excessively. The XR997s seem to use the regular 8p8 connectors, but you need to use cat 6a, not cat 5 cable. There's a lot of variability in 10 gig-e cabling types, which is probably why you're confused.

I'd note other than needing better grade cabling, this is identical to how you'd work with a standard 10/100/1000 network, and should be far simpler. You'd simply need to install drivers, set static ips on either end, and you're cooking with gas.

I don't begin to understand fiber channel - you can use it point to point it seems, however

As for the software side of things, you'll need the server set up as a iscsi target - on linux tgtadm seems to be the thing to use and windows 7 has its own iscsi initator

share|improve this answer
I'm confused about the software end of things, not the hardware. Thanks though! – timramich Feb 2 '12 at 0:08
ahh, I'll update my answer once i've done a little research – Journeyman Geek Feb 2 '12 at 0:08

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.