Joe Uhl wrote:
We have been running Postgres on a 2U server with 2 disks configured in raid 1 for the os and logs and 4 disks configured in raid 10 for the data. I have since been told raid 5 would have been a better option given our usage of Dell equipment and the way they handle raid 10. I have just a few general questions about raid with respect to Postgres: [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.
this depends a lot on the raidcontroller (whether it has or not BBWC for example) - for some use-cases softwareraid is actually faster(especially for seq-io tests).
[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.
well the answer to that question depends on what you are using for your network monitoring as a whole as well as your Platform of choice. If you use say nagios and Linux it makes sense to use a nagios plugin (we do that here with a unified check script that checks everything from LSI-MPT based raid cards, over IBMs ServeRAID, HPs Smartarray,LSI MegaRAID cards and also Linux/Solaris Software RAID). If you are using another monitoring solution(OpenView, IBM Directory,...) your solution might look different.
Stefan
