I would like to design the system disks for data warhouse and I don't know which type of RAID to chose Raid 5 or Raid 0+1. Which should you suggest and why?
With no doubt, if what you are looking for is to preserve your data, to have good warranty that you can recover data without lost ( 95% time ). I Definetly recommend you to go hardware raid 5. With it if you lost one drive you can recover, you can configure hot spares, so there is more security for your data.
Raid 5 is never a good reason not to backup data as accidents happen all the time.
Raid 0+1 is a good solution for a small bussiness and cheaper than Raid 5.
data warehouse will generally have sequential access, so raid-5 provides good performance for this. raid 0+1 will be MORE EXPENSIVE than raid-5, 50% overhead vs. 20-25% overhead (that is for 4+1 or 5+1 raid-5), more or less drives in a raid group can make that figure go up or down a bit. if you do lots of random writes, then you would want to seriously consider 0+1.
Taulant, I use 0+1 which it's good for us as we have a small number of servers and not that critical. Raid 5 provides more security I believe. Also have u considered RAID ADG? This is what i have copied from somewhere : "RAID ADG allows two drives to fail simultaneously without downtime or data loss." "RAID ADG is an extension of RAID 5 that allows additional fault tolerance by using two different and independent parity schemes. Data is striped across a set of hard drives, just as with RAID 5, and the two sets of parity data are calculated and written across all the drives in the array.
RAID ADG provides an extremely high level of fault tolerance and can sustain two simultaneous drive failures without downtime or data loss. This fault tolerance level is the perfect solution when data is mission critical"
