background: having a performance issue with a SuSE Linux boxe accessing
a DB2 database running on zOS.
|------ db2 Database---|
| Server |
| |
hipersocket |-------db2Connect-----| Ethernet
| Server |
| |
|-------App server-------|
So, there is an App server accessing a DB2 database via a db2Connect
server. Both the app server and the db2 connect server are running
Suse10 (as VMs of zOS).
They all have ethernet and hipersocket connections.
If I ping from the App server to the db2connect server the return times
are shorter on the hipersocket connection (expected). But I noticed when
copying a large file (350MB) from the db2Connect server to the App
server via the hipersocket the xfer speed was only 2MB/sec! So I tried
it the other way (from the App server to the db2Connect server) and the
speed was the same pitiful 2MB/sec.
So next I copied the file from the App server to the db2Connect server
using the Ethernet port and the speed was 12MB/sec (expected on a 100Mbs
connection). And I copied it back with the same 12MB/sec results.
This was the "AH HA!" moment last night when I figured out that their
problem was with the hipersocket configuration. Not so fast... This
afternoon I was asked to try the same test again with ftp vs. scp. To my
surprise the transfer speed with ftp was over 100MB/sec on the
hipersocket. WTF? How can it go from 2MB/sec with scp to 100MB/sec with
ftp??? There isn't that much overhead with scp is there? Perhaps
whatever is causing the scp to be so slow is also causing the db2 access
to be slow???
Any ideas on how to isolate this problem?
Rob.
p.s. I just got a reply back from the other party involved:
I’m pretty sure the reason is that scp does encryption and since we
don’t have an encryption co-processor it needs to use the IFL and
the GP to do the encryption and decryption and that slows it down
(evidently considerably).
This would only be a problem for DB2 transaction if the data is
being encrypted when it goes across the network.
Humm... I would think that the DB2Connect and the data transfer were
encrypted...
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