On 01/23/2011 12:40 AM, Spelic wrote:
On 01/22/2011 09:36 PM, Michael Evans wrote:
Also, you are half right about this being a 'dream' system. For years
I've been using a carefully selected 6 port motherboard, and 3 PCI-e
1x cards to get a total of 12 ports.
So you are trying to reach 12 ports?
C'mon don't be cheap, there are lightning-fast 16-ports HBA controllers
from LSI, at 6.0gbit/sec, $350 or so. $25 per port is not much; it is
much less than the cost of the disk you are attaching to it.
This frees you from the choice of the mainboard, and this is important,
firstly because you can save $$$ in there, and secondly because if the
mainboard fails, what are you going to do? you are going to buy another
one with 6 ports? Difficult to find... and expensive also.
Also using 2 different controllers for your disks (part from mainboard,
part from addon card) is a bit of pain in the *** for administration
things, also performances would be the slowest of the two for every
request.
Since we're talking about "non hardware raid" usage, I don't really
understand how it would be harder to manage mixed controllers? Care to
explain? I can't quite get the performance statement to compute,
either.. Its not like the same I/O goes out to all controllers. If your
other controller is slower, just put fewer drives on it. Balance it out.
Anyways, If you settle for SATA and a desktop motherboard, most mid to
high end s1156/1155 motherboards nowadays are fitted with 6 to 8 SATA
ports. They're in now way hard to come by - even 8 ports seems to be
available at $130 (I spent 10 seconds looking on newegg). But then again
not all of them will *boot* off 3TB drives - at least many of the 1156 ones.
As for on board performance, integrated Intel ICH's AHCI controllers
tend to top out at around 750MB/s aggregate. 6 ports are usually on the
Intel, the rest on some AHCI compatible chip from Marvell. In general
you can expect around 1GB/s aggregated from the on board controllers at
the same time on a standard socket 1156/1155 desktop class intel chipset
based motherboard.
Regarding the AOC-SASLP-MV8, yes, they're not worth it - the mvsas
driver is still buggy when used with SATA. I have heaps of issues with
mine - at least when using Seagate 7200.11 1.5TB drives on 2.6.36.3.
Keeps stalling and throwing IO errors (no corruption yet, though). The
card also tops out at ~700MB/s aggregate - and we can't have any of that
can we ;-)
So yeah, the LSI based cards are seems like a good bet if you go the SAS
HBA route. Even the previous 3Gb/s generation can do a cool
1600-1700MB/s if you give them 8 pcie lanes. If he ever plan to expand
into expander (he he) territory, that bandwidth is good to have. Well,
in a "dream system" anyway, any normal workloads are generally more
random and much, much lower in throughput. But hey, we're going for
bragging rights here, right? :-)
--
To unsubscribe from this list: send the line "unsubscribe linux-raid" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
