Re: Larry Ellison comments on Microsoft's benchmark

Is this a strength or a weakness for HA? In shared nothing, a node has exclusive ownership of a disk If it goes down, another node can take over the disk without having to compete with anyone, and there is no need to use a distributed lock manager to request access to the disk.

With shared disk, a node can fail, and the disk cannot be released to another node to start crash recovery (replaying any transactions in the logs) until other nodes accessing that disk get out of the way. Hence the need for another layer of locking (the distributed lock manager). There are HA advantages to shared disk: work can be directed to another node without first having that node establish ownership of the disk (the disk already belongs to more than one node anyway). Perhaps an application need not reconnect to the IP of the node that failed (as is the case with shared nothing).

bob1_at_sns-access.com wrote:

> On Wed, 05 Jul 2000 10:58:24 -0400, "Garfield A. Lewis"
> <galewis_at_ca.ibm.com> wrote:
>
> >Ivana Humpalot wrote:
> >
> >> Thank you for your honest and straightforward answer.
> >>
> >> This basically means the TPC-C benchmark is not extremely useful.
> >>
> >> Although IBM's result tops the charts, the IBM system as used
> >> in the benchmark test may not be as reliable as some other vendor's
> >
> >Please..., let us know of any other TPC-C benchmark that includes HA...
> >
> Galewis,
> The harder question is "Which Oracle Cluster *didn't* have HA.
> Basically oracle has to have it to work since it's a kind of symmetric
> server. All nodes have to have access to the database disks...
> Think about what it means to say oracle is not shared nothing .
> Bob
Received on Thu Jul 06 2000 - 00:00:00 CDT