Re: Advice sought on moving to AMD64
lsorense@csclub.uwaterloo.ca (Lennart Sorensen) writes:
> On Mon, Jun 20, 2005 at 03:18:16PM -0400, Nathan Dragun wrote:
>> I hardly see how 24 cables versus 2 is hardly even something you'd have
>> to consider making a choice about. SCSI channels can take one heck of a
>> beating, besides, your point is irrelevant since you can have the same
>> software raid you'd use for SATA over several SCSI channels as well.
>
> I would prefer a hardware SATA raid like the 3ware cards if doing more
> than 2 drives.
Actualy using the onboard SATA on the Hypertransport gives you more
speed than a normal PCI Bus. Not sure if PCI-X can compete speed wise.
Also software raid with many drives will be faster on the cpu then the
card. But it will cost you cpu time. For a fileserver that needs fast
I/O and has nothing else to do software raid will be faster. For
e.g. a database that also needs to compute stuff hardware can
distribute the load better.
So it all depends.
>> Lastly, all SATA drives have either IDE or SCSI interfaces anyways
>> before they go to the SATA channel.
>
> No quite a few new SATA drives are native SATA and are not IDE or SCSI
> internally.
A lot of drives have identical drives and just different motherboards
stuck onto them for the pata/sata/scsi driver.
> The scsi cable shared by all scsi drives in a system is fairly fragile,
> and loosing it looses all drives, and in some cases a drive failure
> takes out the bus too. With a cable per drive that problem at least
> goes away. It doesn't solve the issue of what happens if the controller
> dies, but scsi has that issue too unless running multiple controllers on
> the bus (which is an advantage of scsi very few people take advantage
> off. Maybe SAS will change that).
A dying drive might electrocute the controler. Lets go fiberchannel. :)
> I used to be a scsi fan, and built machines that used scsi instead of
> ide, but not anymore. SAS I can see a point in, plain scsi I can't.
Scsi is still more robust but one can just buy more disks and do
better raid with ide for the same price to counteract the crappiness
of the individual disk.
> Len Sorensen
MfG
Goswin
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