On Thu, 23 Jun 2005, Eric Wagar wrote:

EW> Depending on the version of NetWorker will depend on how many parallel save
EW> streams you can run.  For us, we have the Network edition, so we get 64.
EW> With a library with 10 drives, we use all 64 streams on a save.  We, like
EW> others, can only use one stream on a tape based recover.

What server do you have that can manage that? What aggregated throughput 
speed to you get?

We have a Sun V440, with 4 1281MHz Ultrasparc IIIi CPUs with 1MB cache, 
and that server can handle just about 1gbit of throughput, before the 
kernel just can't get more CPU time. We're using the built-in ce (Cassini) 
NICs. It seems like the excessive CPU useage is caused by network 
processing. We can't use jumbo frames, since some network equimpent, that 
the clients are attached to doesn't support it.

To me, the excessive amount of CPU used to produce 1gbit of network 
throughput seems just plain wrong, since I seem to remember that the ce 
chipset has TCP checksum acceleration? Or are there any faster NICs in 
this regard, how about the bge chipset? Or would a better CPU (same 
speed, but larger cache, and yes I know I need to get a new server 
then :) ) with a larger cache do the trick, since we see a lot of context 
switching going on?

The funny thing is that if I stream data to the drives alone, without 
reading the data from the network, it takes very little kernel CPU.

//Oscar

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