Re: Hardware performance - Mailing list pgsql-performance

>Adam Witney wrote:
>> Actually I am going through the same questions myself at the
>moment.... I
>> would like to have a 2 disk RAID1 and a 4 disk RAID5, so
>need at least 6
>> disks....
>>
>> Anybody have any suggestions or experience with other
>hardware manufacturers
>> for this size of setup? (2U rack, up to 6 disks, 2
>processors, ~2GB RAM, if
>> possible)
>
>I tend to use either 1U or 4U servers, depending on the
>application. But
>I've had good experiences with IBM recently, and a quick look on their
>site shows the x345 with these specs:
>
>*  2U, 2-way server delivers extreme performance and availability for
>demanding applications
>*  Up to 2 Intel Xeon processors up to 3.06GHz with 533MHz front-side
>bus speed for outstanding performance
>*  Features up to 8GB of DDR memory, 5 PCI (4 PCI-X) slots and up to 6
>hard disk drives for robust expansion
>*  Hot-swap redundant cooling, power and hard disk drives for high
>availability
>*  Integrated dual Ultra320 SCSI with RAID-1 for data protection
>
>This may not wrap well, but here is the url:
>http://www-132.ibm.com/webapp/wcs/stores/servlet/CategoryDispla
> y?catalogId=-840&storeId=1&categoryId=2559454&langId=-1&dualCurrId=73
>
> Handles 6 drives; maybe that fits the bill?

[naturally, there should be one for each of the major server vendors,
eh?]

I've used mainly HP (as in former Compaq) machines here, with nothing
but good experience.  HPs machine in the scame class is the DL380G3.
Almost identical specs to the IBM (I'd expect all major vendors have
fairly similar machines). Holds 12Gb RAM. Only 3 PCI-X slots (2 of them
hotplug). RPS. 6 disk slots (Ultra-320) that can be put on one or two
SCSI chains (builtin RAID controller only handles a single channel,
though, so you'd need an extra SmartArray controller if you want to
split them). RAID0/1/1+0/5.

If you would go with that one, make sure to get the optional BBWC
(Battery Backed Write Cache). Without it the controller won't enable the
write-back cache (which it really shouldn't, since it wouldn't be safe
without the batteries). WB cache can really speed things on in many db
situations - it's sort of like "speed of fsync off, security of fsync
on". I've seen huge speedups with both postgresql and other databases on
that.


If you want to be "ready for more storage", I'd suggest looking at a 1U
server with a 3U external disk rack. That'll give you 16 disks in 4U (2
in the server + 14 in the rack on 2 channels), which is hard to beat. If
you have no need to go there, then sure, the 2U machine will be better.
But I've found the "small machine with external rack" a lot more
flexible than the "big machine with disks inside it". (For example, you
can put two 1U servers to it, and have 7 disks assigned to each server)
In HP world that would mean DL360G3 and the StorageWorks 4354.

The mandatory link:
http://h18004.www1.hp.com/products/servers/platforms/index-dl-ml.html



Though if you are already equipped with servers from one vendor, I'd
suggest sticking to it as long as the specs are fairly close. Then you
only need one set of management software etc.


//Magnus