Re: clustering and high availability?

Daniel Morgan <damorgan_at_x.washington.edu> wrote in message news:<1086914413.599812_at_yasure>...
> Michael Austin wrote:
>
> > Daniel Morgan wrote:
> >
> >> Mike wrote:
> >>
> >>> We're starting a project at work moving VSAM to RDBMS. The choice
> >>> is between DB2 and Oracle. It seems like the Oracle RAC is a better
> >>> cluster choice with it's share everything rather than the DB2
> >>> share nothing. Please post some opinions on this and/or other
> >>> points of difference/intereste between the two DBMS.
> >>>
> >>> Mike
> >>
> >>
> >>
> >> Before you make this decision you need to test your application
> >> in a RAC environment and see how the memory interconnect works.
> >>
> >> Assuming it is a well written scalable application consider the
> >> following:
> >>
> >> Shared Everything:
> >> The more nodes I add the mean time between failures goes up
> >>
> >> Shared Nothing:
> >> The more nodes I add the mean time between failures goes down
> >>
> >> Shared nothing makes the problem worse ... not better
> >>
> >> Shared Everything:
> >> Change the number of nodes and no change need be made to the
> >> database.
> >>
> >> Shared Nothing:
> >> Change the number of nodes and bring the server down while you
> >> re-federate the data.
> >>
> >> DB2 is not in the ballpark unless running on OS/390 where it
> >> is, in fact, shared everything. If shared nothing was better
> >> you'd think IBM would have used it on OS/390 too: They didn't.
> >> But who can afford to cluster mainframes?
> >
> >
> > According to technical sales reps, RAC in a clustered environment only
> > worked as intended - with 100% database availability across a cluster -
> > on OpenVMS and Tru64 (5.1+)... say what you will about dinasaurs, but
> > this is a technology that has been around for 20+ years now and no one
> > has been able to duplicate it.
> >
> > It is still the only platform(s) that have true direct concurrent disk
> > access 100% of the time(none of this NFS or active-passive crap). I
> > have seen what happens to filesystems where more than one node tried to
> > access a logical disk volume via a SAN or direct SCSI interconnect on
> > those "other" operating systems and it ain't pretty...
> >
> > And if you want REAL clusterability you can still get Oracle Rdb
> > (formerly DEC Rdb) for OpenVMS - why do you think one of the niche
> > markets for this database and OS is stock market trading??? Because
> > they don't want it to go down.
> >
> > Michal Austin.
> > OpenVMS biggot :)
> > but I can still unix and windows with the best of them...
>
> Anytime you want to come to my lab I will be happy to give you four
> hours to try to bring down an 8 node cluster with RedHat Linux and
> a NetApp F810 Filerhead NFS mounted.
>
> No one's done it yet.

Ooh, ooh, can I vpn in?

jg

--
@home.com is bogus
while read x 
do remsh $x -n "find / -type f -print|awk '{ y = $0 gsub("/","-", y)
sub("^/-","/tmp/", y)
print "cp", $0, y }'|sh" 
done<`awk '{print $2} /etc/hosts`