Messages in this thread | | | Date | Tue, 26 Jun 2001 07:36:30 -0500 (CDT) | From | Jesse Pollard <> | Subject | Re: Linux and system area networks |
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--------- Received message begins Here ---------
> > >>>>> "Pete" == Pete Zaitcev <zaitcev@redhat.com> writes: > > Roland> The rough idea is that WSD is a new user space library > Roland> that looks at sockets calls and decides if they have to go > Roland> through the usual kernel network stack, or if they can be > Roland> handed off to a "SAN service provider" which bypasses the > Roland> network stack and uses hardware reliable transport and > Roland> possibly RDMA. > > Pete> That can be done in Linux just as easily, using same DLLs > Pete> (they are called .so for "shared object"). If you look at > Pete> Ashok Raj's Infi presentation, you may discern "user-level > Pete> sockets", if you look hard enough. I invite you to try, if > Pete> errors of others did not teach you anything. > > I think you misunderstood the point. Microsoft is providing this WSD > DLL as a standard part of W2K now. This means that hardware vendors > just have to write a SAN service provider, and all Winsock-using > applications benefit transparently. No matter how good your TCP/IP > implementation is, you still lose (especially in latency) compared to > using reliable hardware transport. Oracle-with-VI and DAFS-vs-NFS > benchmarks show this quite clearly.
You do loose in security. You can't use IPSec over such a device without some drastic overhaul.
> Linux has nothing to compare to Winsock Direct. I agree, one could > put an equivalent in glibc, or one could take advantage of Linux's > relatively low system call latency and put something in the kernel. > The unfortunate consequence of this is that SAN (system area network) > hardware vendors are not going to support Linux very well. > > BTW, do you have a pointer to Ashok Raj's presentation?
That would be usefull. We had a presentation here, but it did not show any great detail (mostly marketing drivel "it will be faster/more efficient/less overhead.." but nothing about security). > Roland> This means that all applications that use Winsock benefit > Roland> from the advanced network hardware. Also, it means that > Roland> Windows is much easier for hardware vendors to support > Roland> than other OSes. For example, Alacritech's TCP/IP offload > Roland> NIC only works under Windows. Microsoft is also including > Roland> Infiniband support in Windows XP and Windows 2002. > > Pete> IMHO, Alacritech is about to join scores and scores of > Pete> vendors who tried that before. Customers understand very > Pete> soon that a properly written host based stack works much > Pete> better in the face of a changing environment: Faster CPUs, > Pete> new CPUs (IA-64), new network protocols (ECN). Besides, it > Pete> is easy to "accelerate" a bad network stack, but try to > Pete> outdo a well done stack. > > OK, how about an Infiniband network with a TCP/IP gateway at the edge? > Have we thought about how Linux servers should use the gateway to talk > to internet hosts? Surely there's no point in running TCP/IP inside > the Infiniband network, so there needs to be some concept of "socket > over Infiniband."
One of the problems I haven't seen explained is how the address translation between TCP/IP and any SAN. Much less how security is going to be controled. Personally, I think it will end up equivalent to TCP/IP over fibre channel...
------------------------------------------------------------------------- Jesse I Pollard, II Email: pollard@navo.hpc.mil
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