Re: [gentoo-user] {OT} Need a new server

[Alan McKinnon]

On 13/09/2013 22:00, Grant wrote:
> It's time to switch hosts.  I'm looking at the following:
>
> Dual Xeon E5-2690
> 32GB RAM
> 4x SSD RAID10
>
> This would be my first experience with multiple CPUs and RAID.  Advice
> on any of the following would be greatly appreciated.
>
> Are there any administrative variations for a dual-CPU system or do I
> just need to make sure I enable the right kernel option(s)?

Just use the right kernel options, nothing special needs to be done.

Individual packages may or may not benefit from lots of cpus, such
packages must be configured individually of course


> Is the Gentoo Software RAID + LVM guide the best place for RAID
> install info if I'm not using LVM and I'll have a hardware RAID
> controller?

Exactly what RAID controller are you getting?

My personal rule of thumb: on-board RAID controllers are not worth the
silicon they are written on. Decent hardware raid controllers do exist,
but they plug into big meaty slots and cost a fortune. By "a fortune" I
mean a number that will make you gulp then head off to the nearest pub
and make the barkeep's day. (Expensive, very expensive).

Sans such decent hardware, best bet is always to do it using Linux
software RAID, and the Gentoo guide is a fine start.

> http://www.gentoo.org/doc/en/gentoo-x86+raid+lvm2-quickinstall.xml
>
> Since RAM is so nice for buffers/cache, how do I know when to stop
> adding it to my server?

When more RAM stops making a difference.

The proper answer to your question is "mu", meaning it can't really be
satisfactorily answered with the info available. Only you can really
answer answer it, and only after you have examined your system in
detail. But, assuming you will use this hardware for mostly routine
normal tasks, 32G RAM is heaps and should be plenty for a long time to come.

Nothing you've ever posted leads me to believe you need crazy amounts of
RAM. It's not like your business model is to eg load every public blog
at wordpress.com with all comments and store it all in an in-memory
database :-)

>
> Can I count on this system to keep running if I lose an SSD?

Yes. If you do RAID even half-way right, you can always tolerate the
loss of one disk out of four. It's only if you do striping that you have
no redundancy at all


>
> Is a 100M uplink enough if this is my only system on the LAN?

You mean 100M ethernet right?

100M is actually a lot of traffic. However, if you have a file server
and you have on it big files > 1G, it can become a drag waiting that
extra minute to push 1G through the network.

Your NICs on that hardware are 99.9% guaranteed to be 1G. It is well
worth the money to replace your switch with a 1000Mb model and invest in
decent cables. It's not expensive (a fraction of what that hardware will
cost) and you will be glad you did it, even if all the other clients are
100M

Law of diminishing returns doesn't apply here. It's a whole lot of bang
for relatively little buck

>
> Is hyperthreading worthwhile?

Yes. Horror stories about hyperthreading being bad and badly implemented
date back to 2004 or thereabouts. All that stuff got fixed.

Some software out there does not like current hyperthreading models, but
these are a) rather specialized and b) the issue is known and the vendor
will tell you upfront.

Software that uses threads in the modern style tends to fly if
hyperthreading is available. But again, this is a very general answer
and YMMV

>
> Any opinions on Soft Layer?

Never heard of it.
What is it?



-- 
Alan McKinnon
alan.mckinnon@×××××.com