Re: [sheflug] Assessing server requirements

[David Willington <david.willington [at] xxxxxxxxxxxx>]

On Wed, 2006-06-07 at 17:01 +0100, Gary Stimson wrote:
> Hi David
> 
> David Willington wrote:
> > Dear All
> > 
> > I need to work out a specification for a production server. Can anyone
> > point me in the right direction for methods to work out what I need?
> > It'll be a LAMP server running moodle for a school of about 1600 users
> 
> Some things to consider, in no particular order:
> 
> In terms of methods, I think you're trying to determine how much
> processing power etc is required? You didn't say how many of those 1600
> users will be using the server during any period. I'm guessing around
> 100 max? Of those, you'll get a few short load spikes while each class
> starts up the application and then each individual user will probably
> only be making demands of the server for a small percentage of the time?
> You don't need a particularly powerful server for this by today's
> processor standards.

Thanks for the pointers. I was vague because I've only a rough idea of
how many machines the school has and how much use is likely to be made
of the server. However your guestimate looks good and 'you don't need a
particularly powerful server' is good news. For disk usage, I was
planning to allocate 50Mb a user. How much spare capacity would you
recommend I leave on a hard drive so that it performs as it should?

> At the moment, we put Pentium D 930 3.0 dual core chips in the rack
> servers we specify because they have performance rivalling a dual Xeon
> system for a fraction of the cost and power consumption. The chips are
> about £116 from distributors. The 3.0 chips have max power consumption
> of 95W; for 3.2GHz+ it's 130W.

Do I need to think about hardware differently from the way I'm used to?
At the moment I just buy the cheapest bits I can find for running at
home, and use managed hosting for websites so I've not had to deal hands
on with a server as such. Are the components for a server the same sort
of things as for a desktop?

> If the school would prefer a quiet/low power consumption/lowish cost
> server then consider using a system based around the new Intel Core
> Solo/Duo chips. If physical space is an issue, a pentium-4 system on a
> 
> Use at least 2 disks in RAID 1 mirror or 3 disks in RAID 5 to protect
> data in case of disk failure. If you want to use the server as a general
> filestore server also (which will make little demand of the processor)
> then it's a good idea to have the database partition on separate disks
> for speed.
> 
> Speaking of RAID, don't bother with on-board ICH5R etc motherboard RAID
> because you're generally better off with linux software RAID. If you
> want hardware RAID then 3ware cards rock but are overkill unless the
> disks are going to be in heavy use.

Will mug up on RAID

> Are you supporting this hardware? If so then it's wise to have the
> server email you in the event of disk failure (look at mdadm if using
> software raid) etc.

Yes, at least in the first instance. The school has technicians who are
Windows people, but I'm planning to show them how to get round a Linux
box.

> 
> After disks, the next biggest causes of server failure are failed fans
> and PSUs. If you are supporting the hardware, consider using lm_sensors
> to monitor fan speeds and CPU/case temperatures and alert you where
> necessary. Therefore check the motherboard is lm_sensors compatible.
> 
> I'm sure you've remembered to think about backups. :-)

Backups are already in place - I think there was some surprise that
Linux could back up onto a windows server!



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