[NTLUG:Discuss] RE: true hardware/intelligent ATA RAID -- FRAID cards can get good desktop performance

[Richard Geoffrion]

----- Original Message ----- 
From: "Bryan J. Smith" <b.j.smith at ieee.org>

> And if you do lots of writes, _never_ do FRAID/software RAID-5. 
> RAIDCore likes to show off its _read_ RAID-5 performance (which is like
> RAID-0 minus 1 disk at reads), but you _kill_ your systems
> CPU-memory-I/O interconnect with 3x+ the traffic.  It's not just the
> XORs, but the fact that you must copy _all_ data into the main CPU
> to calculate the XORs -- that's just killer, especially as you add
> more and more disks!
> 
> It's far, far better to do RAID-5 with an intelligent RAID controller.
> You push the same amount of data into I/O like it wasn't RAID at all.

OK...so what I'm reading is NO SOFTWARE RAID-5.  .....BUT.!...
What if the server's entire roll in life is to be a backup server?  In lieu
of swapping tapes, I was hoping to swap several  four disk raid-5 sets.
Once I install the RAIDTAB file as a persistant superblock, those four
disks would be forever married and handled beautifully.  If I put in a 
hardware RAID card, how will the system handle the swapping of 
different 'backup-sets' (of drives)?

Wait a minute.....I don't need to do raid-5 for this.  I can just do
RAID-0 and stripe the data across three disks with no  redundancy.
They are just glorified backup drives anyway. Three 250Gig ide drives 
in scsi trays = 750Gig of backup storage.  Speed isn't necessarily the
issue...the Gigabit backbone is going to be the limiting factor anyway.

I do need to take a look at the 3ware controllers..but I need to make
sure that the ide drives can be hot-swapped.  I have to say that I'm
concerned that using a hardware controller for my specific task might
limit the application of solution creativity to my particular problem.

Off to do more reading.  Thanks guys.

-- 
Richard