Re: Poor RAC inter-instance performance

"Ivan Vasquez" <ivan_at_looker.itos.uga.edu> wrote in message news:<c4f3eo$2je$1_at_cronkite.cc.uga.edu>...
> Yes Mike, I have both, and for the interconnect I have entries on
> /etc/hosts.
>
> Right now I'm considering tweaking the sysctl.conf as Daniel has suggested.
> Any other suggestions are welcome. I would also like to hear if others have
> had the same issues.
>
> Ivan.
>
> "Mike Ault" <mikerault_at_earthlink.net> wrote in message
> news:37fab3ab.0403301206.470e1965_at_posting.google.com...
> > "Ivan Vasquez" <ivan_at_looker.itos.uga.edu> wrote in message
> news:<c4aafk$897$1_at_cronkite.cc.uga.edu>...
> > > I'm testing a 2-node Linux RAC installation that's performing poorly
> under
> > > certain circumstances. The cluster is using 1G NICs as interconnect. I
> > > already know I'm not supposed to ask for great performance out of it,
> > > however the interconnect's capacity is far from reached whenever I
> notice
> > > bad performance.
> > >
> > > Here is the behavior:
> > >
> > > With only one instance up, any query runs quickly, as expected.
> > >
> > > With both instances up, I connect to instance A, run a long query (say,
> > > 30-seconds) and it runs normally. At this point I assume instance A has
> > > cached some or all the blocks used for the query.
> > >
> > > Then I connect to instance B and issue the same query as above. Rows are
> > > returned intermittently, up to 4-second delays in between. I assume in
> this
> > > case RAC is trying to ship whichever buffers are found in instance A
> instead
> > > of reading from disk. No DML activity is going on, it's just me and the
> > > database.
> > >
> > > What confuses me is that I don't see much traffic thru the interconnect,
> and
> > > CPU and disk utilization are far from high. Using vmstat I see increased
> > > context switches, but they are just as high as those in the instance
> that
> > > runs fine! I have read note 181489.1 but haven't found much help from it
> and
> > > wonder if it's something else inherent to my architechture (i386).
> > >
> > > Thanks in advance for any clues.
> > > Ivan.
> >
> > Of course I mean a private interconnect and public network...not to
> > confuse the more literal of the group...
> >
> > Mike

Ivan,

I tried to send you some tuning ideas, but your email bounced back as not found.

Mike Received on Thu Apr 01 2004 - 13:26:10 CST