Re: Storage array advice anyone?

stephen,
i havent use this specific kind of storage array, but here are some thoughts anyway...

• one large storage pool (ie everything striped accross all devices) can create problems when trying to increase capacity and/or when you lose a spindle. this is because the storage controller must 're-level' all storage to account for the new spindle count. this process can take many hours (days) and cause the array to get quite busy.
• you may want to consider separating raid 5 from raid 10 (for redo logs etc)
• if you are like us, you dont have a good understanding of the applications that will be placed on the array and so its safer (performance wise) just to put everything everywhere. we also lack the staffing & performance toole and infrstructure to identify performance bottlenecks before they happen
• as long as the storage arrray is set up right (ie spare disks assignable for a group of disks that have not single point of failure) fault tolerance should not be an issue.
• we have experienced mullti spindle outages at the same time (after power loss of a few hours) so dont assume you're safe because you can recover from single spindle loss
• yes, mutliple mirrored (or duplexed or whatever) controllers in differemt locations is the way to go.

good luck

steve

"Stephen Lee" <Stephen.Lee_at_DTAG.Com>
Sent by: oracle-l-bounce_at_freelists.org
12/13/2004 01:29 PM
Please respond to Stephen.Lee  

        To:     <oracle-l_at_freelists.org>
        cc: 
        Subject:        Storage array advice anyone?

There is a little debate going on here about how best to setup a new system which will consist of IBM pSeries and a Hitachi TagmaStore 9990 array of 144 146-gig drives (approx. 20 terabytes). One way is to go with what I am interpreting is the "normal" way to operate where the drives are all aggregated as a big storage farm -- all reads/writes go to all drives. The other way is to manually allocate drives for specific file systems.

Some around here are inclined to believe the performance specs and real-world experience of others that say the best way is keep your hands off and let the storage hardware do its thing.

Others want to manually allocate drives for specific file systems. Although they might be backing off (albeit reluctantly) on their claims that is it required for performance reasons, they still insist that segregation is required for fault tolerance. Those opposed to that claim insist that the only way (practically speaking) to lose a file system is to lose the array hardware itself in which case all is lost anyway no matter how the drives were segregated, and if they really wanted fault tolerance they would have bought more than one array. And around and around the arguments go.

Is there anyone on the list who would like to weigh in with some real world experience and knowledge on the subject of using what I suppose is a rather beefy, high-performance array.

--
http://www.freelists.org/webpage/oracle-l



--
http://www.freelists.org/webpage/oracle-l