I didn't mean to pick on you specifically,, I was just pointing out
that it would be very difficult to justify from a business perspective,
huge amounts of DASD if you have a stable environment and fault-tolerant
devices. I realize not everyone has all of those things, so I apologize
for those that don't and still stand by my opinion about mirroring being
excessive in certain shops.
> -----Original Message-----
> From: Pittson, Timothy ,HiServ/NA [SMTP:tpittson AT HIMAIL.HCC DOT COM]
> Sent: Tuesday, January 06, 1998 12:33 PM
> To: ADSM-L AT VM.MARIST DOT EDU
> Subject: Re: ADSM mirroring vs. AIX mirroring
>
> David,
>
> If you read thru my note, I wasn't engaged in any 'scare tactics' but
> was replying to the question 'if you were going to use AIX or ADSM
> mirroring', which would you use. I was simply offering an opinion on
> what I would use if those were my options In my case, the ADSM DB is
> on
> a 7137 disk array and this provides sufficient redundancy in the
> hardware to warant not having to mirror the database. However, when
> we
> ran on ADSM on MVS, I made the decision to mirror the ADSM DB - it
> was
> spread out across many 3390-2 disks. For those of you familiar with
> mainframe disk technology, the 3390-2 disk drives had some reliability
> problems as they became 'more mature' :-). This saved me from having
> to
> recover the ADSM DB on 5 different occasions over a 2-3 year period.
> Any decision on mirroring or any form of redundancy needs to be
> predicated by such things as how critical the system is, how long
> would
> it take to recover, how much would it cost to provide that redundancy,
> etc.
>
> Tim
>
> p.s. Doesn't DB2 provide other means of redundancy such as dual disk
> logging, table mirroring, and MVS related stuff such as data set level
> dual copy using SMS, etc. ?
>
> >-----Original Message-----
> >From: Sanders, David [SMTP:DSanders AT INTERNAL.MASSMUTUAL DOT COM]
> >Sent: Tuesday, January 06, 1998 9:18 AM
> >To: ADSM-L AT VM.MARIST DOT EDU
> >Subject: Re: ADSM mirroring vs. AIX mirroring
> >
> >Wow, this sounds suspiciously like the old scare tactics that would
> >cause folks to buy a ton of hardware!! To double your capacity just
> so
> >that you "have a prayer that a bad write during ADSM crashed" only
> got
> >propogated to 1 of the mirrored sets, is unjustified. Since ADSM is
> >stable program-wise, if that improbable corruption occurred, how
> about
> >using the recovery procedures? MassMutual hasn't had ANY corruption
> of
> >DB's (crossed fingers) in the last 2 years. Think of how much
> mainframe
> >DASD we've saved. If this philosiphy was common practise,, would we
> >have to mirror DB2 and other DB's?? Yikes, there goes the hardware
> >budget!!!!!!!
> >
> >> -----Original Message-----
> >> From: Pittson, Timothy ,HiServ/NA [SMTP:tpittson AT HIMAIL.HCC DOT COM]
> >> Sent: Monday, January 05, 1998 11:45 AM
> >> To: ADSM-L AT VM.MARIST DOT EDU
> >> Subject: Re: ADSM mirroring vs. AIX mirroring
> >>
> >> Joe,
> >> If it comes down to using ADSM or AIX to mirror the
> database,
> >> I'd use
> >> ADSM mirroring. I think the big advantage to using ADSM mirroring
> is
> >> in
> >> the event of the system crashing during a DB write and causing DB
> >> corruption. With AIX mirroring, I think you're SOL but with ADSM
> >> mirroring, if the write didn't complete to both copies of the DB,
> you
> >> stand a chance of one copy of the database not being corrupted.
> >> Regarding RAID, I had posted questions to the ADSM-L listserver a
> >> couple
> >> of years ago about this and received some very helpful information
> -
> >> somebody had even done some benchmarking (7137 array vs. SCSI vs.
> SSA
> >> or
> >> something like that - this was a long time ago - at the time, the
> 7137
> >> outperformed the other options ). We decided on using a dedicated
> >> 7137-514 disk array configured for RAID-5 w/hot spare for our ADSM
> DB
> >> (16 GB) and have been very happy with the performance. There had
> also
> >> been some posts about using mirroring/striping with SSA disks but I
> >> don't know what the results of that were. I keep the recovery logs
> on
> >> separate dedicated SSA disks and use ADSM mirroring to mirror them.
> >>
> >> Tim Pittson
> >>
> >>
> >> >-----Original Message-----
> >> >From: Joe Morris [SMTP:morris AT UNC DOT EDU]
> >> >Sent: Monday, January 05, 1998 10:49 AM
> >> >To: ADSM-L AT VM.MARIST DOT EDU
> >> >Subject: ADSM mirroring vs. AIX mirroring
> >> >
> >> >I've been browsing through the ADSM archives at Marist and could
> not
> >> find
> >> >what I was looking for. Setting up a new server that has ample
> space
> >> to
> >> >replace our old ADSM server.
> >> >
> >> >What are the pros and cons of using ADSM and AIX to mirror the
> >> database
> >> >and log volumes. Mainly focusing on differences between using AIX
> >> >mirroring and the built-in mirroring in ADSM.
> >> >
> >> >I had considered a RAID configuration, but it seems like that is
> not
> >> such
> >> >a hot solution for the database for performance reasons. Am I
> wrong?
> >> >
> >> >_______________________________________________________________
> >> >Joe Morris - morris AT unc DOT edu - http://sunsite.unc.edu/morris
> >> >Academic Technology and Networks, Development and Eval Services
> >> >University of North Carolina at Chapel Hill PGP by request
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