Re: Harware vs Kernel RAID (was Re: External SATA enclosures: SiI3124 and CentOS 5?)

[John R Pierce <pierce@xxxxxxxxxxxx>]

Chan Chung Hang Christopher wrote:
>> I've read a lot of different reports that suggest at this point in time, 
>> kernel software raid is in most cases better than controller raid.
>>   
>>     
> Let me define 'most cases' for you. Linux software raid can perform 
> better or the same if you are using raid0/raid1/raid1+0 arrays. If you 
> are using raid5/6 arrays, the most disks are involved, the better 
> hardware raid (those with sufficient processing power and cache - a long 
> time ago software raid 5 beat the pants of hardware raid cards based on 
> Intel i960 chips) will perform.
>   

not if you're doing committed random writes such as a transactional 
database server... this is where a 'true' hardware raid controller with 
significant battery backed write cache will blow the doors off your 
software raid.


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