LSI SATA RAID (again)

[Hans du Plooy <hansdp-lists@sagacit.com>]

Hi guys,

This is getting weirder.  First, I found that one can disable "fast 
initialization" in the card's firmware.  I did this, let the discs 
initialize properly (which took about a day), tried again - no improvement.

I replaced the card with my cheap-o 2-port Sil_3112a card, tested 
writing to the discs independantly, and in kernel based raid, both 
raid-0 and raid-1.  Single disk and raid-0 both gave me between 25mb/s 
and 30mb/s, raid-1 gave me about 20mb/s.

Then I tested single disc on the LSI card, port by port.  Guess what I 
found?  Ports 0, 2 and 4 are dogs, can barely manage 10mb/s.  Ports 1, 
3, and 5 do around 25mb/s.  To confirm this, when I initialized the 
discs, the ones on ports 0 and 2 (I didn't have any on 4) took about 
four times as long as the others.   Anybody know why this is?

Then I decided, OK, let's make a raid5 (in the card's firmware), with 
only three discs on ports 1, 3 and 5 (the "fast" ports).  Again, I 
struggle to reach 10mb/s.  While this copy is in progress, I see my 
system load shooting to over 8.0....

So, my theory:  This card relies on the megaraid driver to do the heavy 
lifting.  The CPU on the board is the older P4 based Celeron 2ghz (128k 
cache), and absolute dog in it's own right.  Maybe this machine just 
isn't strong enough for this type of raid?

000:00:07.0 RAID bus controller: LSI Logic / Symbios Logic MegaRAID (rev 
01)
     Subsystem: LSI Logic / Symbios Logic MegaRAID SATA 150-6 RAID 
Controller
     Flags: bus master, 66Mhz, slow devsel, latency 32, IRQ 11
     Memory at ef000000 (32-bit, prefetchable) [size=64K]
     Capabilities: [80] Power Management version 2

Any insights would be appreciated.

Thanks
Hans