[Info-vax] Unpleasant Disk Shadowing Surprise

[abrsvc]

On Oct 12, 1:29 pm, "Richard B. Gilbert" <rgilber... at comcast.net>
wrote:
> On 10/11/2011 10:24 PM, Phillip Helbig---undress to reply wrote:
>
>
>
>
>
> > In article<j72tl2$6k... at online.de>, hel... at astro.multiCLOTHESvax.de
> > (Phillip Helbig---undress to reply) writes:
>
> >> In article
> >> <1750432.79.1318364167195.JavaMail.geo-discussion-forums at yqv33>, Kenneth
> >> Fairfield<ken.fairfi... at gmail.com>  writes:
>
> >>> But as others have noted, having both shadow members
> >>> on the same scsi bus is problematic.  A single "bad"
> >>> error on the one disk can hang the whole bus...
>
> >> Except for the system disk and perhaps one for swap/page, I wouldn't
> >> have two members on the same node, much less the same bus.  SOPF and all
> >> of that.
>
> > SPOF, of course---single point of failure.
>
> When in doubt, spell it out!  It's not that hard to do.- Hide quoted text -
>
> - Show quoted text -

In a host based shadowing scenerio, a failure of a member WILL NOT
cause the entire DSA device to enter mount verification.  The failure
of BOTH members will.  In this case, I suspect that the disk failure
(DKA100) caused the bus to hang or have problems which caused the
remaining member (DKA0) to enter verification as well.

A good rule of thumb is to have as many pathways as possible.  With
the DS10, use 2 controller cards as I mentioned earlier.  A single and
dual are supported.  Separate the shadow members across the
controllers (DKA and DKB for example) and you should be able to avoid
this in the future. If you'd like specifics, shoot me an email at:

dansabrservices AT yahoo DOT com