RE: [gentoo-user] RAID

> -----Original Message-----
> From: mwq [mailto:mwq@××.pl]
> Sent: 10 March 2007 21:00
> To: gentoo-user@l.g.o
> Subject: [gentoo-user] RAID
>
>
> I have one laic question which may not be directly connected
> to Gentoo but I think you'll forgive me that.
> Imagine such a situation: I have two hard drives but drive A
> is twice faster when reading and writing then drive B. I want
> to make RAID 0 using A and B. Why are the stripes sizes on
> both drives excacly the same? (I've googled and didn't find
> any information about different spripes sizes) I think that
> using twice greater stripe on A gives more speed then using
> equal stripes.
> And my question is: where am I doing a mistake?
> PS
> Sorry for my poor English
>
> --
> gentoo-user@g.o mailing list
>
>


Forgive me the maths approach here, but if drive A reads/writes at speed a, and drive B at speed b.



a = 2*b from what you have said.

In raid 0 drive speed is limited by the slower drive (if I recall correctly) so the speed your raid array would be limited to is .... b + b = 2b = a (from above).



Hence you would be as well not bothering with RAID if drive A is 2x as fast as drive B.



Naturally it's not as clear cut but should be pretty close. RAID 0ing these drives would gain you little in terms of speed while any 2 drive RAID 0 setup increases the chance of failure by 2.



If you just want them to appear as one drive look at something like LVM which can create one volume from both drives, although parts of the volume on drive A would be faster than those parts on drive B.



Just my £0.02, feel free to poke holes in my reasoning ;)





--

djn



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