>When I run 'amdump' to backup Linux hosts, the speed is pretty good.
>When I run 'amdump' to backup Sun Solaris hosts, the speed is extremely
>slow.
>It seems not a network or hardware issue.
As Mitch says, this is almost certainly a duplex mismatch problem.
The Sun hme interface is *notorious* for almost always picking the
wrong setting. As Mitch also said, for lots of things nobody notices.
But when data needs to start really streaming, such as for backups,
performance falls apart.
One indicator of this is "netstat -i". I don't recall which column it
is, but you'll see **lots** of collisions or errors when the duplex is
wrong.
Attached is a little script I ran across called "nicstatus". It knows how
to reach into the Solaris kernel with "ndd" and report what's going on.
Here's the output for one of my machines:
Link: hme0 Autospeed: On
Link: hme0 Status: Up
Link: hme0 Speed: 100Mb
Link: hme0 Mode: Full Duplex
In this case, my Sun box is connected to a Linksys switch that it *does*
properly autonegotiate with (in fact, if you try to force the issue
things go bad in a different way). That's why "Autospeed" is set to "On".
Here it is for a more typical system where autonegotiation has to be
turned off:
Link: hme0 Autospeed: Off
Link: hme0 Status: Up
Link: hme0 Speed: 100Mb
Link: hme0 Mode: Full Duplex
You can make the interface do what you want either via the ndd command
or via /etc/system entries. I've found changing what it's doing at
run time, even during boot, can sometimes not get the job done, so I
usually update /etc/system even though it takes a reboot to take effect.
Here are the entries that match the second system above:
set hme:hme_adv_100fdx_cap = 1
set hme:hme_adv_autoneg_cap = 0
This says "use 100 Mbit/s full duplex" and "do not use autonegotiation".
If you go to docs.sun.com and search for "adv_100fdx_cap" you'll find
all sorts of other information about this mess.
>David
John R. Jackson, Technical Software Specialist, ITaP/RCS, jrj AT purdue DOT edu
nicstatus
Description: nicstatus
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