On 6-9-2007 14:35 Harsh Azad wrote:
2x Quad Xeon 2.4 Ghz (4-way only 2 populated right now)
I don't understand this sentence. You seem to imply you might be able to
fit more processors in your system?
Currently the only Quad Core's you can buy are dual-processor
processors, unless you already got a quote for a system that yields the
new Intel "Tigerton" processors.
I.e. if they are clovertown's they are indeed Intel Core-architecture
processors, but you won't be able to fit more than 2 in the system and
get 8 cores in a system.
If they are Tigerton, I'm a bit surprised you got a quote for that,
although HP seems to offer a system for those. If they are the old
dual-core MP's (70xx or 71xx), you don't want those...
32 GB RAM
OS Only storage - 2x SCSI 146 GB 15k RPM on RAID-1
(Data Storage mentioned below)
I doubt you need 15k-rpm drives for OS... But that won't matter much on
the total cost.
HELP 1: Does something look wrong with above configuration, I know there
will be small differences b/w opetron/xeon. But do you think there is
something against going for 2.4Ghz Quad Xeons (clovertown i think)?
Apart from your implication that you may be able to stick more
processors in it: no, not to me. Two Quad Core Xeons were even faster
than 8 dual core opterons in our benchmarks, although that might also
indicate limited OS-, postgres or underlying I/O-scaling.
Obviously the new AMD Barcelona-line of processors (coming next week
orso) and the new Intel Quad Core's DP (Penryn?) and MP (Tigerton) may
be interesting to look at, I don't know how soon systems will be
available with those processors (HP seems to offer a tigerton-server).
B: Go for Internal of DAS based storage. Here for each server we should
be able to have: 2x disks on RAID-1 for logs, 6x disks on RAID-10 for
tablespace1 and 6x disks on RAID-10 for tablespace2. Or maybe 12x disks
on RAID-10 single table-space.
You don't necessarily need to use internal disks for DAS, since you can
also link an external SAS-enclosure either with or without an integrated
raid-controller (IBM, Sun, Dell, HP and others have options for that),
and those are able to be expanded to either multiple enclosures tied to
eachother or to a controller in the server.
Those may also be usable in a warm-standby-scenario and may be quite a
bit cheaper than FC-hardware.
But for a moment keeping these aside, i wanted to discuss, purely on
performance side which one is a winner? It feels like internal-disks
will perform better, but need to understand a rough magnitude of
difference in performance to see if its worth loosing the manageability
features.
As said, you don't necessarily need real internal disks, since SAS can
be used with external enclosures as well, still being DAS. I have no
idea what difference you will or may see between those in terms of
performance. It probably largely depends on the raid-controller
available, afaik the disks will be mostly the same. And it might depend
on your available bandwidth, external SAS offers you a 4port-connection
allowing for a 12Gbit-connection between a disk-enclosure and a
controller. While - as I understand it - even expensive SAN-controllers
only offer dual-ported, 8Gbit connections?
What's more important is probably the amount of disks and raid-cache you
can buy in the SAN vs DAS-scenario. If you can buy 24 disks when going
for DAS vs only 12 whith SAN...
But then again, I'm no real storage expert, we only have two Dell MD1000
DAS-units at our site.
Best regards and good luck,
Arjen
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