Re: RAID10 explanation and mirroring setup

"Carlson@WHSmith" wrote: > > I've been following the RAID discussions and I'm having a bit of 'DBA > block' when it comes to understanding RAID10. RAID01 is pretty easy: > stripe, then mirror. Somehow the 'mirror, then stripe' explanation > seems a bit vague to me. Could someone point me in the right direction? In my simple terms: RAID01 - Stripe then Mirror 1. If a disk fails: Whole stripe set has to be recovered from the mirror (stripe set) 2. If a disk fails in both stripe sets, you are buggered! RAID10 - Mirror then Stripe 1. If a disk fails: Just that disk has to be recovered from the mirror (disk) 2. If the same two disks fail as above, they are both recovered 3. If a disk AND its mirror fail, you're still buggered! You just have to be careful how you wire up dual controllers, dual power supplies, shelves, etc. > On another note: > > Sometime in the near future (within 2 months), my SysAdmin and I are > going to implement mirroring (as a minimum) on our production system. > His idea was to set up the mirrors using the current rawspace > configuration, restoring an Informix backup, thus populating the > mirror. I was thinking about planning a system reorg in order to take > the opportunity of correcting some table / disk placement issues. (Some > tables have grown out of their 2G rawspace and the only place where I > could put then was on another disk.) We'll be running under some time > constraints. Would the benefit of some table placement changes outweigh > the time involved to export, then import on a mirrored system? I think you've answered that yourself. If you have time constraints and you can't quantify the benefits of a reorg up front (and who can) then go with the restore. You can then do some performance analysis and plan phase two - the reorg. ;-) Cheers, -- Mark. +----------------------------------------------------------+-----------+ | Mark D. Stock mailto:mdstock@mydas.freeserve.co.uk |//////// /| | http://www.informix.com http://www.informixhandbook.com |///// / //| | http://www.iiug.org +-----------------------------------+//// / ///| | |What year 2000 bug? year 2000 bug? |/// / ////| | |year 2000 bug? year 2000 bug? year |// / /////| | |2000 bug? year 2000 bug? year 1900 |/ ////////| +----------------------+-----------------------------------+-----------+