topic Re: Vax CI in Operating System - OpenVMS

Vax CI

Phillip Bruce_2 — Fri, 20 Jun 2003 19:04:13 GMT

It has been years since I've worked on Vaxes and the question was posed to me as followed:

Is the VAX CI considered a SAN (Storage Area Network) as we now it today? If not can you elaborate the differences?

Re: Vax CI

Martin Johnson — Fri, 20 Jun 2003 20:01:10 GMT

The VAX CI can be considered the grand daddy of the SAN, but there are differences.

The VAX CI provides access to storage, but only to members of the cluster, whereas, a SAN can offer access to any member of the network.

Depending on the hardware, SAN throughput may be faster.

Generally, all data in the VAX CI can be shared with all nodes of the cluster. The distributed lock manager handles conflicts and prevents corruption. In a SAN, generally data is not shared and is usually accessed by only one system at a time.

HTH
Marty

Re: Vax CI

Phillip Bruce_2 — Sat, 21 Jun 2003 15:56:23 GMT

Thanks for the comments, I do appreciate that. I have to agree with you after going thru the documents. I'm quite supprise by how much I have forgotten about the Vax Cluster CI.

If memory servers me correctly, The star coupler was nothing but a hughe tranformer interconnect. The HSC controllers I worked with back then were the HSC 70 (I think) and they had 4 RA60's attached along with a mirror in which they called it shadowing back then.

Is there any detail documentation that explains the Fiber Channel protocols to the CI. It seems to me unlike in a true SAN today you have all the FC layers from 0 to 4. Fiber Channel Interfaces came out much later after I left the Vax world to the Unix side.

In my opinion, DEC should never sold out. The Vax systems were way ahead of it's time.

BTW, did get a notification that anyone replied to me question. Please be sure to email me at pbbruce@mindspring.com

Re: Vax CI

Phillip Bruce_2 — Sat, 21 Jun 2003 20:55:22 GMT

Have you or anyone ever replicated the Data over the WAN with a VAX? If so, would you mind sharing your thoughts on that?

Re: Vax CI

Vinit Adya — Mon, 23 Jun 2003 13:53:53 GMT

Hi,

A CI Cluster or Hardware cluster can server disks to any and all nodes connected to the Star Coupler, no matter they are in a VMS cluster or not. Pretty much like a SAN.

Like a SAN, we can have redundant Path of each of the disks/controllers/Tape drives etc.

Unlike a SAN, disk resource level zoning cannot be implimented on the Star Coupler (like one can do on a SAN Switch/Director)

Regards,
Vinit Adya

Re: Vax CI

Keith Parris — Wed, 30 Jul 2003 21:40:37 GMT

> Have you or anyone ever replicated the Data over the WAN with a VAX? If so, would you mind sharing your thoughts on that? <

There are at least hundreds of sites which have used Host-Based Volume Shadowing to replicate (shadow, mirror) disks between clustered VAX systems at two sites.

Such a VAXcluster setup saved Credit Lyonnais from losing their data during a fire in Paris in 1996. More recently, Commerzbank survived the 9/11 attacks thanks to a VMS disaster-tolerant cluster based on Alphas (see http://h71000.www7.hp.com/openvms/brochures/commerzbank/commerzbank.pdf), although I know of others who also survived who used VAX systems in their DT clusters.

I managed a disaster-tolerant VAXcluster with sites 130 miles apart at E*Trade a few years back.

See my DECUS presentations on "Using OpenVMS Clusters for Disaster Tolerance" at http://www2.openvms.org/kparris/ and http://www.geocities.com/keithparris/ for more information.