[Cialug] Guarantee SSH availability

[David Champion]

You can probably find various dead trees books, but they're likely obsolete.

Here's some apache documentation that may be helpful:

http://httpd.apache.org/docs/2.0/misc/perf-tuning.html

What distro are you running this on? All LAMP servers are not created
equal... for instance I've found that RHEL and CentOS tend to be tuned for
conservative performance and stability, especially with the MySQL server,
which may be a good 15 to 20% slower in some cases than other linux distros
running on the same hardware.

-dc

On Tue, Jun 28, 2011 at 3:51 PM, Kenneth Younger <kenny at sheerfocus.com>wrote:

> There's gotta be a book out there about this stuff that's pretty
> comprehensive. Any suggestions?
>
> On Tue, Jun 28, 2011 at 1:24 PM, Matthew Nuzum <newz at bearfruit.org> wrote:
>
>>
>> On Tue, Jun 28, 2011 at 12:06 PM, Kenneth Younger <kenny at sheerfocus.com>wrote:
>>
>>> I'm not sure what exactly occurred. It's a basic LAMP server with an
>>> nginx proxy doing some caching there.
>>>
>>> Running this server has been humbling, because I used to think I knew
>>> what I was doing with regard to running a server - but this thing has given
>>> me a new respect for the subtle configuring that an expert can make.
>>>
>>> I know this isn't HUGE traffic, but it was getting 3000-4000 pageviews an
>>> hour at peak, which is the most traffic I've ever seen on a site I run. I
>>> think my problem is I just don't know how to tell what went wrong after the
>>> fact...
>>>
>>> How would tell if it ran out of memory, or the CPU was just fully pegged,
>>> or the disk started thrashing?
>>>
>>> -Kenny
>>>
>>>
>> I know the feeling.
>>
>> PHP can be a bit harder to tune because the interpreter is part of Apache.
>> Therefore it's hard to estimate how many child processes your system can
>> support. If I was on a 512MB system I'd probably limit it to 20 and double
>> that for a 1G or bigger system. If you find you've got a lot of spare memory
>> under load then you can decide where to put it, often MySQL is a good
>> candidate.
>>
>> I've seen situations like yours happen a few times in the last 18 months.
>> In each case it was out of file handles. If that happens you're toast. You
>> can't log in remotely to do anything about it.
>>
>> What I've done, and has paid off in spades, is run Xen to create my own
>> VPS on a dedicated server. It means you need an extra IP address but it also
>> means you've got a guaranteed bit of a safety net. You can ssh into your xen
>> host (aka dom0) and then take over the console of your vm that's gone out of
>> control and try to fix it or at least hold its hand in its final hour. It
>> also means that a physical server can be divided up into smaller servers
>> which might be convenient. LXC may be a good alternative if you aren't able
>> to run Xen.
>>
>>
>> --
>> Matthew Nuzum
>> newz2000 on freenode, skype, linkedin and twitter
>>
>> "Opportunity is missed by most people because it is dressed in overalls
>> and looks like work." -Thomas Edison
>>
>>
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>>
>
>
> --
> Kenneth Younger III
> Founder, Sheer Focus Inc.
> e: kenny at sheerfocus.com
> p: (515) 367-0001
> t: @kenny <http://twitter.com/kenny>
>
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