virtual provisioning and raw device for database

Hi bertho and welcome to the EMC support forums,

I see that you have full customer rights to the forums, so I would move your question to the proper forum, where more people will see it, but I can't tell what product you are referring to. Can you post some more details please?

Julie
Forums Admin

I've moved this thread from Powerlink Lite to Symmetrix
Julie
Forums Admin

Thank you Julie.

We are using thin provisioning with Oracle 10g on Linux. Assuming you aren't doing it for just the wide stripping aspect but for the oversubscribing "thinness" of it. If you are preallocating the storage and just want to go over a bunch of drives without having to mess with things, there is nothing that the DBA's have to do different.

What you need to make sure is to have your DBA's do autoextend so that Oracle doesn't go through and write 0's to the end of the tablespace and only does it on demand. Many DBA's don't like to do this as everytime you extend it has to lock the table. It's the same locking action anytime a DBA extends a table so it's not really that special, but because it happens at random times rather than when the DBA pushed the button they can "get twitchy" about it since it could happen at peak load. Using a resonable extend size growth tends to remove this issue: i.e. for a database table growing at 10MB/min, don't do 100KB extents growth increments. If DBA's are really, really concerned they can still preallocate some of the space themselves before hand to make sure an autoextend doesn't kick in when they don't want it to.

Only in the most demanding situations does the autoextend performance seem to be that much of an issue anymore (but I'm not a DBA so speak with yours). We are doing it here very successfully, but as a general CYA rule, just make sure to do some tests as my database isn't your database.

Make sure you get the reason for it drilled into all of the DBA's or you'll get some old-school one who you might get/force to turn on autoextend, but will back-end you and preallocate 90% of the storage to oracle and only the last 10% would be autoextended nullifying the overprovision/ondemand benefit of VP.