[aclug-L] Re: RAID question?

[James Lancaster <james@xxxxxxxxxxxxxxxxxx>]

On Thursday 03 October 2002 11:32, you wrote:
> Question about RAID ARRAY
> [ RAID 0 / Level 0 is also referred to as "striping".]
>

'RAID 0' (as I recall, correct me if I am wrong people) (there are arguements 
about it) should not be called a RAID, becasue it does not have any 
redundancy. It basically appends one disk to the other. (actually it just 
stripes the data across, not appending it really)
RAID 0 IS NOT REDUNDANT, and PROVIDES NO DATA PROTECTION.
Ok, my big warning is done. 
You might want RAID 1 (mirroring) which does provide protection if you want 
that. (or any other version of RAID)

> While in a perfect world both harddrives would be the same size, make and
> model...
>
> _But_
>             MUST both drives in a RAID ARRAY be the same size, make and
> model??
>

No, at least not for linux's software RAID. It is based upon partitions on 
the disk. 

> I have two WD drives one 40gb and one 39gb.
> I have an IDE RAID controller which I am currently only using as an add on
> IDE controller.
>

Most of the IDE RAID controllers (cheaper ones anyway) are also software RAID 
(think winmodem) and while they may work as a 'RAID' to windows, because of 
linux's fondness for talking to the real hardware, won't always work. 
Additionally due to their use of the CPU and being software, etc, linux 
software raids are often plus or minus 5% of the performance of the cheaper 
RAID cards. 

I am not saying this is the case, but it may be. Unless you know you have a 
hardware based raid card (which does the processing on itself) It would 
probably be best to use Linux's software RAID (which also handles variety 
much better). The only limitation is that the partitions have to be the same 
size.

James

> --David
>
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