Skip site navigation (1) Skip section navigation (2)

Re: shadowing (like IB/Firebird)

From: "Glen Parker" <glenebob(at)nwlink(dot)com>
To: "pgsql-general" <pgsql-general(at)postgresql(dot)org>
Subject: Re: shadowing (like IB/Firebird)
Date: 2004-04-26 20:25:59
Message-ID: AJEKKAIECKNMBCEKADJPKEMPCCAA.glenebob@nwlink.com (view raw or flat)
Thread:
Lists: pgsql-general
Sounds an aweful lot like RAID level one :-)  Why would a DB system need to
do what RAID already does quite well?

> Sorry, should've at least described 'shadowing'. A shadow is a
> synchronous page-level (I think) mirror file. That is, when you open a
> database /disk1/dbname.fdb and then issue a:
>
>   > CREATE SHADOW 1 '/disk2/dbname.fdb';
>   > CREATE SHADOW 2 '/disk3/dbname.fdb';
>
> then all 3 files will be kept synchronized at all times. Each subsequent
> page write will go to all 3 files (if any of the write fails, the
> transaction fails, so it's not unlike a synchronous replication).
>
> Now suppose /disk1 fails, one of the shadow can be configured to
> immediately take over as the master database, without any down time. We
> can then add /disk4/dbname.fdb, for instance, to become a new shadow.
>
> Alternatively, when a shadow fails, IB/Firebird can refuse further
> transactions until there is another shadow coming up, so the database is
> shadowed all the time.


In response to

Responses

pgsql-general by date

Next:From: Dave CramerDate: 2004-04-26 20:42:04
Subject: Re: [JDBC] loading data into postgresql became slow
Previous:From: Guy FraserDate: 2004-04-26 19:58:57
Subject: Re: 7.3.4 on Linux: UPDATE .. foo=foo+1 degrades massivly

Privacy Policy | About PostgreSQL
Copyright © 1996-2014 The PostgreSQL Global Development Group