topic Re: OpenVMS RA8000 w/ software shadowing in Operating System - OpenVMS

OpenVMS RA8000 w/ software shadowing

Kyle Snavely_1 — Mon, 21 Jul 2003 12:13:58 GMT

Does anyone know if there's a performance advantage when using VMS software shadowing with the RA8000 (HSZ80) and staggering the mirrored pair across ports?

ex. D=Drive, O=Open Slot

OOOOOO
OOOOOO
DOOOOO
ODOOOO

Instead of:

OOOOOO
OOOOOO
DOOOOO
DOOOOO

Thanks

Re: OpenVMS RA8000 w/ software shadowing

Richard W Hunt — Thu, 24 Jul 2003 19:16:49 GMT

Regardless of the performance, there is an issue of single points of failure if you DON'T stagger the drives across ports as you suggest.

Staggering is better.

Re: OpenVMS RA8000 w/ software shadowing

Warren Landrum — Thu, 24 Jul 2003 21:39:47 GMT

Kyle,

As Richard says, the main advantage of staggering is for fault-tolerance for a mirrorset so that you don't have them both on the same channel. (assuming channels are running up and down as in you having both drives in the 1st channel in your 2nd example)

I don't know if there would be much of a performance advantage unless you perhaps had each channel going to a different controller.