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

[Christopher Chan <christopher.chan@xxxxxxxxxxxxxxx>]

John R Pierce wrote:
> 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.
>
>
>   


See my reply to nate. If you are using boards with 12GB of cache, 
software raid is not even on the radar.
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