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VMWare ESX 4.0 RAID 5 vs RAID 10

I can either use my ESX 4 host with 6 HDs setup in RAID10 (ie. 3 spindles) or with 5HDs in RAID 5 (ie. 5 spindles) + 1 Hot Spare. Which configuration would be faster for the highest IOPS ?

PS. I do not care at all about storage size...
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Vincent D
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Vincent D
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Vincent DAuthor Commented:
FYI

The HDs are all Near Line SAS running on a Dell PERC 6 controller...
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Joseph GanSystem AdminCommented:
In this particular case, on average RAID5 with five disks would be faster than RAID10 with three disks. However, with RAID10, read would be faster because it reads from both mirroring sides, as if it has six 6 spindles. But writes is the slowest of all, it only writes to three disks and mirroring to other three which takes a little more time.
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Alex GalbraithSolutions ArchitectCommented:
It comes down to a question of performance vs reliability and will depend on your sepecific useage of apps etc installed on your machines. Heres a quick breakdown:

Performance                                   RAID5                              RAID10
Reliability                                          Good                               Excellent
Random Read                                 Excellent                        Excellent
Random Write                                  Fair                                 Very Good
Sequential Read                              Very Good                     Excellent
Sequential Write                              Fair                                 Very Good

Recommended Use                      V good for read only     Good read and write
Its also worth noting you will not have 5 spindles of true data read/write, only 4 as the 5th is being used for CRC, and there is a tiny performance hit caused by the time to calculate and write the check bits. Overall the RAID10 will provide a better read and write balance and better redundancy. Based on the above I would pretty much always recommend RAID10 if you are happy with the cost to performance efficiency of it.

Note: If your apps are mainly read only on the local disks you could consider the RAID5, but the question is, do you really need the extra disk space (one spindle), and are you willing to risk the loss of 2 disks?
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Vincent DAuthor Commented:
Is This Performance Difference going to be noticable if the ESX 4 host is running approx 15 - 16 VMs? We have various VM servers running like AD, Exchange, Database, File/Print, Medical software etc. etc.
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