Joe Uhl wrote:
[1] What is the performance penalty of software raid over hardware raid? Is it truly significant? We will be working with 100s of GB to 1-2 TB of data eventually.
One thing you should appreciate about hw vs sw raid is that with the former you can battery-back it and enable controller write caching in order to make disk write latency largely disappear. How much of a performance difference that makes depends on what you're doing with it, of course.
See the current thread "Two hard drives --- what to do with them?" for some discussion of the virtues of battery-backed raid.
[2] How do people on this list monitor their hardware raid? Thus far we have used Dell and the only way to easily monitor disk status is to use their openmanage application. Do other controllers offer easier means of monitoring individual disks in a raid configuration? It seems one advantage software raid has is the ease of monitoring.
Personally I use nagios with nrpe for most of the monitoring, and write a little wrapper around the cli monitoring tool from the controller manufacturer to grok whether it's in a good/degraded/bad state.
Dell PERC controllers I think are mostly just derivatives of Adaptec/LSI controllers, so you might be able to get a more convenient monitoring tool from one of them that might work. See if you can find your PERC version in http://pciids.sourceforge.net/pci.ids, or if you're using Linux then which hw raid module is loaded for it, to get an idea of which place to start looking for that.
- Geoff ---------------------------(end of broadcast)--------------------------- TIP 2: Don't 'kill -9' the postmaster
