[Info-vax] RDB Question

[Kerry Main]

> -----Original Message-----
> From: Info-vax <info-vax-bounces at rbnsn.com> On Behalf Of Arne Vajhøj
> via Info-vax
> Sent: December 4, 2018 8:43 AM
> To: info-vax at rbnsn.com
> Cc: Arne Vajhøj <arne at vajhoej.dk>
> Subject: Re: [Info-vax] RDB Question
> 
> On 12/3/2018 9:50 PM, Kerry Main wrote:
> >> From: Info-vax <info-vax-bounces at rbnsn.com> On Behalf Of Arne Vajhøj
> >> Sent: December 3, 2018 3:17 PM
> >> On 12/3/2018 12:41 AM, Phillip Helbig (undress to reply) wrote:
> >>> In article <pu1po7$oh5$1 at gioia.aioe.org>, =?UTF-
> >> 8?Q?Arne_Vajh=c3=b8j?=
> >>> <arne at vajhoej.dk> writes:
> >>>> Mimer if it still supports VMS.
> >>>
> >>> Not really an alternative to Rdb.
> >>
> >> Mimer is a relational database server.
> >>
> >> I think I looked a little into it 15-20 years ago, but I do not
> >> remember anything.
> >>
> >> Any particular shortcomings compared to RDB.
> >
> > Std question I always have for DB's on OpenVMS when comparing to Rdb -
> > does the DB support active-active clustering?
> 
> Active/active is rarely a hard requirement.
> 
> If one look at Oracle and DB2 then even though they have RAC and PureScale
> then only a small fraction actually use them.
> 
> > May of the popular DB's today like MySQL (if memory serves correctly)
> > do not support active-active .. only the traditional active-passive mode.
> 
> MySQL can do active/active cluster, but it is using data replication not shared
> storage.

Active-active implies full read-write directly to the DB from any system. Hence, you can not do active-active using data replication.

You also need a DLM to coordinate the writes between servers (either at OS or DB level)

Kerry