[Shameless Plug] Re: [OT] Server choices?

[Daniel Smith]

> >My company is starting to think about buying some server hardware and I 
> >wanted to get some feedback on what makes a good server.
> >
> I work for TPG, so I figure I may as well plug their products:
> 
> http://www.pc.tpg.com.au/servers.php
> 
> The things that make "good" servers from TPG's point of view:
> - reliability of the hardware
> - RAID controllers

You missed one. Maintainability. Hardware breaks. How long it keeps your
server down for (to replace) is important. Hot-swappable everything.

> These machines only use on-board video, since they're not intended to be 
> placed in front of humans.

Real servers(tm) don't have video. They have serial consoles.
Surprisingly enough, PC server boards are now starting to come with
this "feature", finally.

> The main feature of a server is reliability, the second is performance 
> (as opposed to a high end workstation, which will often put performance 
> first, and reliability a distant second). For a database server, you 
> will usually want fast disk I/O, rather than fast processors - so RAID 
> is essential, and lots of RAM won't go astray either ("RAM" in Linux 
> speak being read as "disk buffer" ;)

Note RAID != SCSI. Many people (obviously on a budget) have reported
good performance etc using 3ware's IDE raid controller. 

> Note that most "server" class machines will use ECC RAM, to avoid data 
> getting corrupted by stray gamma rays. If you want to cut the price of 
> your server, you might consider using standard SDRAM (on a standard 
> workstation motherboard) - but be aware that SDRAM is not as reliable 
> (safe to your data) as ECC RAM! TPG servers come with 2 network 
> interfaces - if you're not saturating your Internet connection yet, you 
> won't need to worry so much about having 2 interfaces unless you're 
> multihoming the server.

The other thing a server (hopefully) provides is a NIC that provides
some support for unburdening the CPU. 
At one end of the market you have the Realtek 8139. Saturating 100M
ethernet is basically impossible with less than ~800Mhz of processor.
At the other end you have kit like the Tigon3. Support for zero-copy
TCP, interrupt coalescing and other things that generally let your
CPU get on with crunching data, not being an interrupt handler and DMA
engine.

> You might want to think about getting a P4 on a motherboard that 
> supports hyperthreading too - I've heard reports that under Linux you 
> can get as much as 30% extra performance out of the P4 when 
> "HyperThreading" is enabled.

Unfortunately, on a server I wonder how much of that performance gets 
eaten by the P4's lousy syscall performance.
The situation looks grim for the next 6-12 months.

Read this lkml thread.
http://www.uwsg.indiana.edu/hypermail/linux/kernel/0212.1/0139.html

Daniel