Software RAID 5 or something else?

[Phil Meyer]

aragonx at dcsnow.com wrote:
> Hello all,
>
> I had a drive failure a few months back so I decided it was time to rework
> my home server's storage.
>
> Now I have 5 750GB SATA dives and now I need some advice on how to set
> things up.
>
> My original idea was to put them in a RAID 5 configuration.  This sounded
> good until I started researching RAID controller cards.  It looks like it
> will cost me $520 to get a good PCI-E card (3Ware 8 port).  I don't think
> I want to spend that much if I don't have to.
>
> My goals are two fold.
>
> 1) I want to get some redundancy in case of a drive failure.
>
> 2) I want to increase my performance.  I have benchmarked my read and
> write performance to and from this server.  Using Samba, I seem to be able
> to get about 50Mb/sec reads and 40Mb/sec writes.  I am on a gig network
> and would like to be able to max out the cards (90Mb/sec is what I get at
> work).
>
> So, the question is, what should I do?
>
> 1)  Bite the bullet and get the hardware RAID controller.  Will this give
> me the performance I want?
>
> 2)  Go with a software RAID 5.  Will I lose performance with this
> configuration?  If I use this but only get modest performance gains, that
> would be acceptable.
>
> 3)  Go with some other software RAID level.
>
> Any help would be appreciated.
>
> ---
> Will Y.
>
>
>
>   

If you understand that there is really no such thing as hardware based RAID.

There is 'dedicated hardware' based RAID, which is software based RAID 
on a card that does nothing else but RAID.

Most of these RAID cards have a small, slow, CPU, and relatively slow 
RAM modules to run the RAID software.

So considering that, what do you gain from dedicated hardware for RAID?  
You get a commercially supported RAID software and hardware package, and 
you get to unload a bit of CPU from the main system.

Considering that the CPU on the card at max performance is probably 1/3 
of a core from a modern CPU, then that is not really much of a savings.

The real consideration for RAID 5 is survival.  In either situation you 
have to have a spare drive, and you have to consider availability of new 
drives to match them in the future.

Good Luck!