K. Norbert's questions

We have moved one of our sites to a new server, which once in a while completely hangs. At first this happened very rarely, maybe once per month, but now it's starting to happen every day. By hangs, I mean that all the requests time out, and trying apache2ctl status, or apache2ctl graceful in a shell results in apache2ctl waiting indefinitely. Only issuing a apache2ctl restart brings it out of this state. I can't seem to find anything in the apache error logs, the access logs indicate that apache is indeed not serving requests.

Currently the server is mostly serving a single site, a rapidshare-like file sharing portal, serving around 1TB data. It is running ubuntu lucid, has 8GB of ram and a quad core intel xeon cpu, with apache-mpm-itk and PHP 5.2.11.

It has munin running on it, and at the times when apache is hanging, it is showing a very high number of threads (650+). The usual number of threads is around ~200, and it goes to 650 in about 1 hour of time. Running ps at this time reveals that it is indeed apache who has a lot of children running. CPU load/memory usage doesn't seem to be a problem, at the moment it's using only 1.1GB of RAM, and load is 0.05.

I have been told that Lighttpd, or nginx would have been a much better solution for this kind of site. I'm willing to switch, but I'd rather try and make it work with this setup. (the old server was running apache too)

Was mpm-itk a bad idea? I mostly chose it for the security of having each virtualhost run under a different user. It's running on the default configuration pulled from the package manager, which is bad I know, but I'm not sure which values I should tune.

I'm posting some values that might be relevant, please ask for anything else if needed:

Timeout 300
KeepAlive on
MaxKeepAliveRequests 100
KeepAliveTimeout 15

<IfModule mpm_prefork_module>
    StartServers          5   
    MinSpareServers       5   
    MaxSpareServers      10  
    MaxClients          150 
    MaxRequestsPerChild   0   
</IfModule>

So, what values should I be looking at? Is there anything particular that I should grep the logs for?

I and a small group of developers have just moved to a new office, and I'd like to set up dnsmasq on our development server, so when we deploy web apps there, we don't have to edit our own hosts files. We have a router at 192.168.3.1 which we don't have access to. I figured I'd install a DNS server on the development box, and we all record its IP as a secondary DNS server. Unfortunately, I'm struggling to make this work.

The name of the devel server is devbox, its IP is 192.168.3.99, and it's running the latest Ubuntu Server (Karmic)

My computer is running Ubuntu Desktop (Karmic)

What I'd like to achieve

Let's say I have three websites, website1, website2, website3, running on the development box. I'd like to access them by the URLs:

http://website1.devbox
http://website2.devbox
http://website3.devbox

So I have configured Apache on the devel box, installed dnsmasq, and put the following lines into its hosts file:

192.168.3.99 website1.devbox
192.168.3.99 website2.devbox
192.168.3.99 website3.devbox

and edited my own resolv.conf file to include the devel box as a nameserver:

nameserver 192.168.3.99 

It's working fine, I can access the sites. The problem is that it doesn't scale well. I'd like all the domains ending with .devbox forwarded to the development box, and this is what I'm struggling with.

I have tried putting

192.168.3.99 devbox

into the hosts file, and editing the line in dnsmasq.conf:

# Add local-only domains here, queries in these domains are answered
# from /etc/hosts or DHCP only.
local=/devbox/

But I cannot get it working. If I try any URL that is not explicitly present in the development box's hosts file, the DNS lookup fails.

Is the local directive for something else? Am I looking at the wrong place?

I would like to mirror one drive's partition table, that is, have exactly the same partition on both sda and sdb. I have heard that one of the fdisk utilities can export a partition table into a file, and that file can be read back into another drive, but I can't seem to find this in the manuals.

Can someone help?

To summarize: I want to have the exact same partitions on both drives, same labels, same filesystem types, and same sizes. The data on the drive does not matter, I just want the partition table.

Let's say I have a software raid1 array from two partitions. I get one HDD out of the computer, and put it into another computer, and copy some data to the mirrored partiton.

What happens when I put the HDD back into it's original place? Will the new data get mirrored to the other drive? If yes how does the controller check/notice that there is new data on the drive? Surely it can't check the whole partition on every boot.

Also, what happens when I delete a file in the same scenario as above? Will it get deleted back from the other drive, or will it get copied back?

This is on an Ubuntu machine, and by getting the drive out, I mean that the computer is completely turned off while doing this, and is only turned back on the when the drive is back in it's place.

If the raid controller does not recognize the change because the power is off while doing this, is there a way to instruct it to reconstruct the array? Like, let's say that raid is constructed from /dev/sda1 and /dev/sdb1, I turn off the computer, and pull out the sdb drive, copy data to it, put it back, and now I want to instruct the controller to reconstruct the array, using /dev/sdb1 "as a master".