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Solving Slow Logins and Poor Performance on Applications that use Small Files

Novell Cool Solutions: Tip
By Eric Belcher

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Updated: 9 Feb 2006
 

Updated with new suggestion:

If you have other suggestions, please send them to oesmag@novell.com and we'll post them here.

PROBLEM:

Slow Logins, poor performance on applications that use small files.

SOLUTION:

Reduce the buffer size on the NIC in INETCFG

Using network traffic tool I realised I had high latency onto and between servers.

By reducing the NIC buffer size to 128, my latency was greatly reduced and my average thru-put trippled.

ENVIRONMENT:

OES 6.5SP3 NetWare
Client varies: 4.83, 4.91, 4.91Sp1
Slow logins and NAL loading ZENworks 6.5
Slow applications: LABVOLT, Medical Director

Other Suggestions

Geoffrey Carman

He does not specify what setting he changed to 128.

Also a very common issue for slow performance is a duplex mismatch. 100 Meg Ethernet supports (poorly) Full duplex. The problem is in Flow Control. Gigabit Ethernet requires that you specify a flow control method. 100 Meg allows you to not specify.

One solution that we have seen work across platform (WinNT, Win2K, Solaris, Linux, and Netware) is to run servers at 100 Meg Half Duplex. This is counter intuitive, since one would expect Full Duplex to perform faster. But when you are talking to a slower client (say a 10 Meg ether client), then the 100 Meg server can easily overflow the clients connection with data. The switch port will buffer for a while, but not very long. Then it starts throwing away packets. No problem, TCPIP will notice the missed packets and resend, but that just excerbarates the problem as more packets pile up as the server keeps overflowing the port.

By switching the server to half duplex, then there are at least collisions on the wire to slow down the flow of data, giving the slower client a chance to catch up.

FTP is usually a good test tool to see this in action. Performance is about full load for the 10 meg link, then it starts to slow down to a crawl.

The key though is to make sure that the switch port is hard coded to 100 Half, and that your server is hard coded to 100 Half as well. The worst thing is to have those two settings mismatch.

Gigabit ethernet talking to 100 Meg clients can see similar performance, it is just harder to saturate a 100 Meg link, than a 10 Meg link. And the Gigabit end of it at least has flow control turned on from the switch to the GigE client.


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