Mirror / Raw device / Informix

Dear IIUG, I would like to ask if I can do a mirror of my database which is installed on raw device into the 2 server by using mirror technology. I heart that this solution won't work with Informix but I'm not sure therefore I asked the question on IIUG. Is there any tool by Informix can help me to mirror the database of my raw device? Are there anyway to build redundant system for my database server? I used Informix 10.0 and as OS Suse Enterprice Linux Sever 9 Any help will be grateful Regards, Muthana AL-Temimi

High Availability data replication?

Muthana.AL-Temimi@tu-harburg.hamburg.de wrote: > Dear IIUG, > > > > I would like to ask if I can do a mirror of my database which is > installed on raw device into the 2 server by using mirror technology. > > I heart that this solution won't work with Informix but I'm not sure > therefore I asked the question on IIUG. > > > > Is there any tool by Informix can help me to mirror the database of my > raw device? > > Are there anyway to build redundant system for my database server? > > > > I used Informix 10.0 and as OS Suse Enterprice Linux Sever 9 > > Any help will be grateful You can also look at drbd and linux-ha Work fine with Informix and raw devices

<Muthana.AL-Temimi@tu-harburg.hamburg.de> wrote: > Dear IIUG, > > I would like to ask if I can do a mirror of my database which is > installed on raw device into the 2 server by using mirror technology. > > I heart that this solution won't work with Informix but I'm not sure > therefore I asked the question on IIUG. It should work fine, you can do it the OS level if you want, but I don't Suse well enough to know the exact commands. Within informix use the onspaces command to add the mirror devices, if it complains about mirroring being disabled then edit the ONCONFIG to turn it on, stop and start the engine and redo the onspaces commmand > > Is there any tool by Informix can help me to mirror the database of my > raw device? > > Are there anyway to build redundant system for my database server? Yes, lots of ways. How much has to be redundant? > > I used Informix 10.0 and as OS Suse Enterprice Linux Sever 9 > > Any help will be grateful > > > Regards, > > > Muthana AL-Temimi

Muthana.AL-Temimi@tu-harburg.hamburg.de wrote: > Dear IIUG, > > > > I would like to ask if I can do a mirror of my database which is > installed on raw device into the 2 server by using mirror technology. <SNIP same question asked 4 ways.> To understand, you seem to be saying that you want to use some kind of live clustering or SAN level mirroring to set up redundant Informix servers on two machines. Correct? If that's so, the answer is almost, and only if the mirroring can handle the RAW devices. If you want a cold failover, this will work fine. When/if the primary server machine fails the HA software/scripts can start a copy of Informix on the backup server accessing the mirrored or linked drives. No problem as long as the latency of the mirroring is near zero. Otherwise there may be situations where the disks on the backup machine will be inconsistent in a way that prevents Informix from running successfully. There are better solutions however. As hinted by others, Informix provides two levels of database replication that can be used to maintain a secondary server which is either a hot backup system for failovers only or which is indeed a live server which can be accessed anytime with up-to-date data. These are respectively known as HighAvailability Data Replication (HDR) and Enterprise Replication (ER). Neither uses OS or disk vendor services for replication. Both rely on Informix technology which maintains all servers (2 for HDR and as many as you want for ER) in perfect synch (if synchronous replication is configured) and always consistent (even when configured for asynchronous replication). See the Informix Systems Administrators Guide and the Enterprise Replication Guide contained in the online Informix IDS manuals for details. Art S. Kagel

Muthana.AL-Temimi@tu-harburg.hamburg.de wrote: > Dear IIUG, > > > > I would like to ask if I can do a mirror of my database which is > installed on raw device into the 2 server by using mirror technology. <SNIP same question asked 4 ways.> To understand, you seem to be saying that you want to use some kind of live clustering or SAN level mirroring to set up redundant Informix servers on two machines. Correct? If that's so, the answer is almost, and only if the mirroring can handle the RAW devices. If you want a cold failover, this will work fine. When/if the primary server machine fails the HA software/scripts can start a copy of Informix on the backup server accessing the mirrored or linked drives. No problem as long as the latency of the mirroring is near zero. Otherwise there may be situations where the disks on the backup machine will be inconsistent in a way that prevents Informix from running successfully. There are better solutions however. As hinted by others, Informix provides two levels of database replication that can be used to maintain a secondary server which is either a hot backup system for failovers only or which is indeed a live server which can be accessed anytime with up-to-date data. These are respectively known as HighAvailability Data Replication (HDR) and Enterprise Replication (ER). Neither uses OS or disk vendor services for replication. Both rely on Informix technology which maintains all servers (2 for HDR and as many as you want for ER) in perfect synch (if synchronous replication is configured) and always consistent (even when configured for asynchronous replication). See the Informix Systems Administrators Guide and the Enterprise Replication Guide contained in the online Informix IDS manuals for details. Art S. Kagel

Art S. Kagel wrote: > Muthana.AL-Temimi@tu-harburg.hamburg.de wrote: > > Dear IIUG, > > > > > > > > I would like to ask if I can do a mirror of my database which is > > installed on raw device into the 2 server by using mirror technology. > <SNIP same question asked 4 ways.> > > To understand, you seem to be saying that you want to use some kind of live > clustering or SAN level mirroring to set up redundant Informix servers on > two machines. Correct? > [cutting] Suse clustering works very well, got a couple clients running this. They use a dual attach SAN, when box fails the clustering software brings the other server online, plays with IPs, etc. The only loss is the current transactions, the appservers loose their connection and just reconnect. The end users, the whole app is web based, never really notice - they put it down as slow internet Paul Watson Oninit Ltd Tel : +44 1414161772 Cell : +44 7818 003457 Web : www.oninit.com