Building a server, which cpu would be best?

I am starting a web hosting company and would like to know what stresses the system will be dealing with mainly, what kind of processor would be suitable? is there any point going for a quad core prossessor as there wont be many applications running?

If say 500-1000 users were connecting what would be the biggest issue in terms of hardware? ...RAM...CPU...Disk speed?....

cheers

chris

Building a server, which cpu would be best?

The new processors allow more distribution of tasks so although you may not have many applications running it will allow concurrent tasks to be split and keep throughput high.

You might for example have a particular data base program running alongside something else, the new processors allow this to be distributed with far more ease than before.

With servers your main itinery is redundancy and reliability, for that you nearly always have 2 of everything (network cards, fans etc) this allows a partial failure without the need for total loss of service.

Most servers support %26quot;hot swap%26quot; of fans, PCI-e cards and hard drives which further reduces the need for a power down.

Some will even offer hot spare memory so if a Dimm fails it will take it out of circuit and switch in your hot spare.

Finally you need to look at the drives themselves, again if you go for basic mirrored drives you get speed with redundancy, the over heads are quite high though on processing power to service two drives at the same time.

Raid 5 spreads data and parity over a minimum of three drives and again can tolerate a single drive failure, normally with auto rebuild of the failed drive - you can also install a hot spare drive which will come active the moment any drive fails.

New RAID systems use Raid 7 which allows 2 drives to fail and others use combinations of mirroring and striping (RAID 1+0 etc).

The way we set our servers is plenty of Ram to allow the system to flex itself when required - always have 2 CPU%26#039;s so it has fall back in case one fails.

The OS we tend to install on mirrored drives for the ultimate speed - we normally use the SCSI controller built into the server system board for this, we then install at the very least a Raid 5 array for the data using a decent Raid card with BBWC (Battery Backed Write Cache) the cache prevents corruption in the event of sudden power failure. Using two arrays with two different RAID configurations allows a balance of speed and robustness, the RAID 5 controller handles the disk access independent of the CPU so does not incur large over heads - we always fit a hot spare on the RAID 5 array if we can so our minimum set up would be 2 hard drives for OS plus 4 for the Raid 5 (most of our servers we sell have 6 drive slots).

Finally we fit gigabit network cards (make sure they are balanced on the PCI bus so you can team then with the correct OS load balancing for optimum data throughput and least CPU over heads), then we ensure a backup solution - quite often an SDLT offering good data transfer rates with proven reliability.

Before it then gets stress tested we ensure it has the correct amount of fans - if you purchase a server it often has 1/2 the number of fans it can actually take and sometimes has slots for additional power supplies, we expand both of these - one we built recently for example had only 2 fans, it now has 7 - it had 1 power supply, it now has 3 and it had 2 hard drives, it now has 12 split into two RAID 5 arrays.

This server is used by my workshop team daily so it cannot be allowed to fail under normal circumstances, ensuring it has redundant components addresses that to a great extent.

Team all of this up with a good UPS solution (ours is connected to a 3KVA rack mount UPS) and your assured of good mains filtering and protection from spikes, brown outs etc.

Unfortunately you only get what you pay for so it pays to stick to industry names on servers, HP, IBM etc - parts are easily available, support is readily available and you are normally guaranteed hardware spares support for 5 -7 years.

HP (or Compaq as they used to be known) give lifetime warranty on their server memory - it is regarded as the most reliable memory available and having been a Compaq engineer for almost 25 years I can vouch for that.