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Conference 7.286::fddi

Title:	FDDI - The Next Generation

Moderator:	NETCAD::STEFANI

Created:	Thu Apr 27 1989
Last Modified:	Thu Jun 05 1997
Last Successful Update:	Fri Jun 06 1997
Number of topics:	2259
Total number of notes:	8590

1721.0. "PCNFS <-> OSF1 over FDDI performance. What should I get? " by LARVAE::TREVENNOR_A (A child of init) Mon Jun 19 1995 14:01

    Xposted from the NFS conference.
    
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             -< SunNet - the defacto distributed system standard >-
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Note 419.0  PCNFS <-> OSF1 over FDDI performance. What should I get?  No replies
LARVAE::TREVENNOR_A "A child of init"                16 lines  19-JUN-1995 12:41
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    Hi All,
    		I have a DEC 2100 sitting back to back with a PC over FDDI
    (single attached stations in the server and the PC). The PC is a 66mhz
    486. The Server is running DEC Unix V3. The PC is running PCNFS. 
    
    I have a file in the PC hard disk (an RZ26 which is capable of
    delivering 3.8 Mbytes/sec according to the Adaptec SCSI bench program).
    I want to transfer this file at maximum warp to an RZ28 on the DEC
    2100. I'd expect to be able to put about 800 Kbytes/second downline to
    the server in this scenario (is that realistic?) but in fact I can only
    put about 100Kbytes. In my view something's wrong. Anyone know what, or
    is it my expectations that are wrong!
    
    Regards
    Alan T.

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1721.1 NETCAD::STEFANI Welcome to the Revolution! Mon Jun 19 1995 14:26 20

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1721.1		NETCAD::STEFANI	Welcome to the Revolution!	`Mon Jun 19 1995 14:26`	20
	>>put about 100Kbytes. In my view something's wrong. Anyone know what, or >>is it my expectations that are wrong! If you're running PC-NFS, you're likely using the NDIS 2.01 drivers. These drivers (because of the DOS/Windows architecture) are quite limited in performance compared to the 32-bit drivers. The drivers translate from Ethernet/FDDI on both receive and transmit, they limit the packet size to max Ethernet (~1500 bytes), they use I/O mapping of the adapter registers instead of memory mapping, and they only allocate a few host buffers for transmit/receive because of size limitations. DOS and Windows don't lend themselves that well to Bus Master DMA devices, for other reasons I won't go into, and that's why the industry push towards 32-bit and beyond OS's is so important to vendors like us selling high performance controllers. I would recommend that you use Windows NT rather than DOS and see if you achieve the throughput you're looking for. /l

    >>put about 100Kbytes. In my view something's wrong. Anyone know what, or
    >>is it my expectations that are wrong!
    
    If you're running PC-NFS, you're likely using the NDIS 2.01 drivers. 
    These drivers (because of the DOS/Windows architecture) are quite
    limited in performance compared to the 32-bit drivers.  The drivers
    translate from Ethernet/FDDI on both receive and transmit, they limit
    the packet size to max Ethernet (~1500 bytes), they use I/O mapping of
    the adapter registers instead of memory mapping, and they only allocate
    a few host buffers for transmit/receive because of size limitations.
    
    DOS and Windows don't lend themselves that well to Bus Master DMA
    devices, for other reasons I won't go into, and that's why the industry
    push towards 32-bit and beyond OS's is so important to vendors like us
    selling high performance controllers.
    
    I would recommend that you use Windows NT rather than DOS and see if
    you achieve the throughput you're looking for.
    
    /l