RAID controller question...

[Mark Hahn]

> Thanks for the lead...  Insight had the DPT PM3334UDW for $1275 which
> puts it in the same price range as the ICP GDT6518RD.  As for Mylex,

phew!  I'm not trying to belittle those of you who believe in RAID
hardware, but these prices are enough to stop and make you think.
$1275 is 50G of fast, cool UDMA disk.  yes, such disks will only sustain
12-14 MB/s apiece, but I've heard people report good results using the MD 
driver under Linux.

remember, the touchstone of Beowulf is off-the-shelf, commodity hardware.
$1275 might not blow the budget of a large cluster project, but it's 
worth thinking about whether you'd be better off just using comodity
hardware and mirroring, etc.

(and yes, before you ask, I _have_ measured 12-14 MB/s, sustained,
Ext2 with 4K blocks, on run-of-the-mill Triton/Promise/ViaMVP3-type
UDMA controllers.  depending on the processor, the bandwidth incurrs
7-20% CPU overhead, most probably due to the filesystem, not the disk
interface.)

regards, mark hahn.