akohlsmith
Technical User
I'm trying to maximize throughput between my Samba server and my Win2k clients. Samba's configured to allow up to 64k packets and the server is on a GigE network with SCSI UW2 drives (software RAID1 and RAID5 volumes). All clients are 100MB/sec FDX on a switched LAN.
I can get sustained 35MB/sec transfers (read and write) on the disk subsystem so I know that's not a limiting factor.
I have read the various TCP/IP and throughput tuning documentation for Win2k (and WinNT) found on various sites, including MSDN and the MSKB. My maximum window size is 128k, MTU is 1500 (well auto-discover but packet traces show that this is where it was autonegotiated at)... TCP window scaling is on and so on and so forth... I don't need TCP/IP tuning, I need CIFS and NBT tuning.
No matter what I do I can't get Win2k to give up limiting the maximum NBT packet size to the MSS. All NBT packets (coming or going) max out at 1460 bytes and all packets have the DF bit set. I have extra CPU to spare so I'd like to have 64k NBT packets that are fragmented to fit into the ethernet frames.
Testing with NFS and FTP has shown that I can hit 9.6MB/sec with larger packets, but am stuck down around 4MB/sec with these measly 1-2k packets. I know it's not a Samba-side issue because if I start four or five transfers from different workstations I can easily aggregate their individual transfer speeds and get 20MB/sec on the GigE interface.
So, Win2k gurus -- How do I get _maximum_ NBT performance out of a Win2k box for local LAN traffic? Everything I've read focuses on TCP/IP tuning and increasing the window size, selective ACK and window scaling in order to do better over long thin links. That's not the issue here; I just need fast LAN speed for file transfers.
I can get sustained 35MB/sec transfers (read and write) on the disk subsystem so I know that's not a limiting factor.
I have read the various TCP/IP and throughput tuning documentation for Win2k (and WinNT) found on various sites, including MSDN and the MSKB. My maximum window size is 128k, MTU is 1500 (well auto-discover but packet traces show that this is where it was autonegotiated at)... TCP window scaling is on and so on and so forth... I don't need TCP/IP tuning, I need CIFS and NBT tuning.
No matter what I do I can't get Win2k to give up limiting the maximum NBT packet size to the MSS. All NBT packets (coming or going) max out at 1460 bytes and all packets have the DF bit set. I have extra CPU to spare so I'd like to have 64k NBT packets that are fragmented to fit into the ethernet frames.
Testing with NFS and FTP has shown that I can hit 9.6MB/sec with larger packets, but am stuck down around 4MB/sec with these measly 1-2k packets. I know it's not a Samba-side issue because if I start four or five transfers from different workstations I can easily aggregate their individual transfer speeds and get 20MB/sec on the GigE interface.
So, Win2k gurus -- How do I get _maximum_ NBT performance out of a Win2k box for local LAN traffic? Everything I've read focuses on TCP/IP tuning and increasing the window size, selective ACK and window scaling in order to do better over long thin links. That's not the issue here; I just need fast LAN speed for file transfers.
