> If the background mirroring support is truly transparent and 4D doesn’t know > anything about it and the .4DD and .journal files are not ‘touched’ then I > think it should work.
If the concept is fully transparent, 4D does not know and does not care, yes. I wonder about speed and failure behavior. When you use a local SAN, normally you are not sharing the existing network. You add 2 x 10 Gbit cards, 2 Switches, each 10 Gbit, connected to the SAN, which again as 2 x 10 Gbit cards. The cables are not side by side but as far distance as possible, to get maximum redundancy. If a RAID looses contact to a single disk, yeah, it looses contact. There is nothing like "connection paused, might come back later". So what happens if the network is down for a second? Or a minute? Or your internet connection is down for an hour? We are talking about 24/7, right? Speed: Use any hard disk speed test tool. Setup for a test file similar as your real datafile+index. Test random read 4kb blocks, 8 parallel access, you might add 8 more into the waiting queue. Latency should be in 99% less than 1 ms, max latency < 5ms. IOPS 4 digit or better. If you reach that, you are good to go. Test file size is important. I tested once a (slow) iSCSI Server with 1 GB datafile. It was unbelieveable fast. Doing the same with 10 GB - unbelievable slow. More than 1000 times lower. Why? The 1 GB was just inside my server's RAM, kind of RAM Disk. All cached. If the connection would have been lost, all would have been lost. > and ‘transparent’ OS processes like Windows Shadow Copy which did mess up > .4DD files. There is NO "transparent" Windows Shadow Copy support. This requires major work. If there is no VSS Writer available for a given application/service, Shadow Copy will fail and produce damaged data, but that's another story. 4D Deutschland GmbH Geschäftsführer Laurent Ribardière Telefon: +49-89-856 33 43-0 Amtsgericht München HRB 92258 Fax: +49-89-856 33 43-99 Obere Hauptstrasse 2 E-Mail: [email protected] 85386 Eching - Deutschland Web: www.4D.com ********************************************************************** 4D Internet Users Group (4D iNUG) FAQ: http://lists.4d.com/faqnug.html Archive: http://lists.4d.com/archives.html Options: http://lists.4d.com/mailman/options/4d_tech Unsub: mailto:[email protected] **********************************************************************
