Re: Informix Disk Mirroring

Al Parker writes in Informix-List-Id: <newsgate.202> > ... >-Replicated databases (synchronized and unsynchronized) to ensure >critical data bases are always available. >Does anyone know if this has been realized yet ? What I would like >to achieve is disk-mirroring from one system to another. From what >I can see, the disk-mirroring abilities of INFORMIX ON-LINE 4.0 >(which we are using :') will not support mirroring databases to >remote systems. >Can anyone expand on this or point me in a different direction ? On-line 4.0 does not currently allow database replication and I wouldn't hold your breath waiting for this facility. Other possibilities exist though. 1) If you are only trying to protect a small database and access speed is not vital then you might be able to use cooked file space instead of raw disk and use RFS or NFS to make an equivalent cooked space available on another machine. Online may then be able to mirror to the remote file space. I haven't tried this and you would need to be happy with the reliability of your network but I think it would probably work. All Chunks would need to be mirrored so that the second machine had all the information for launching its own Online session. 2) A number of hardware companies, for example Pyramid, now provide hardware mirroring where the drives can be linked to two machines at the same time. Normally these systems provide Read/Write from one machine and Read only from the other with a 5 minute switch over to swap to the second machine. (With Pyramid the two machines don't need to be the same size so you can have a production and development box with the development box acting as live standby for the main parts of your production systems). As with the first option you cannot have the second box running Online as it requires read/write access so you have to include the time taken to run up Online and your applications into the switch over time. Hope this helps but I can't guarantee either solution. (Disclaimers all round). Cheers Jim -------------------------------------------------------------------- Name: Jim Gordon Internet: jgordon@ssf-sys.DHL.COM Company: DHL Systems Inc Phone: (415) 358-5911 Address: 1700 S. Amphlett Blvd. Fax: (415) 571-6429 San Mateo, CA 94402 --------------------------------------------------------------------