cmhobbs's questions

I've got a pretty standard Rails application running with Unicorn and Nginx all on one box. I'd like to split off the application itself and have Nginx on one machine and Unicorn (with the Rails app) on another machine. The idea here being that I'd like to add another app server with Unicorn later in the future, mostly for some light load balancing.

I may be tackling this from the wrong angle. Is this normal/possible? If so, can someone point me to example configs or documentation?

If it's not the way to go, what's the proper route to achieve the end goal? I've looked into HAProxy, but after reading through some Nginx/Unicorn documentation, I get the idea that this can be achieved without any additional software.

I'm trying to segment a few servers for a Rails project and part of that is entertaining the idea of isolating Resque workers to their own box. I already have Redis broken out, but is it common to put Resque workers elsewhere? Do they need to be tied to the application itself?

If it can be done, are there any commonly referenced best practices or writeups on the subject? If not, am I better off just throwing more RAM at the app servers running Resque workers?

I plan to use foreman to monitor all of this and create upstart jobs.

This is a continuation of ubuntu server, ssh, write failed: broken pipe. I'm starting a new question, because I don't believe the issue is isolated to ssh/ubuntu.

I've got two brand new servers (Dell PowerEdge R715, R210) with Ubuntu server 10.04 64bit installed on them. I'm running a stack of Cisco 3750 switches with two Juniper SRX240 firewall/routers. The setup is basically router on a stick, we have 3 vlans: one internal, one dmz, and one storage network (iSCSI) all on the same stack. No layer 3 switching is being done on the Cisco stack and DMZ is completely isolated from the stack on a different switch.

There are about 10 other Dell PoerEdge servers on this same network (and stack) that have been running for years without an issue. Most of them are running SLES 10 or openSUSE, but one is running Ubuntu server 10.04 64bit. I've unplugged all NICs on these new servers except those going to our internal vlan.

If I boot either (or both) machines and let them sit for about ten minutes, we start getting up to 20% packet loss from other machines on the network and up to 40-50% packet loss from the offending servers.

Does anyone have an idea as to why this might be happening or what I can to do troubleshoot the issue? I don't mind wiping these boxes if I have to, there isn't any production data on them yet.

I'm getting some bizarre behavior with Ubuntu Server 10.04 64bit on two of our new servers (both fresh installs). I have ubuntu server (same version) deployed on 4-5 other servers without this issue.

Initially I cannot ssh into a fresh server install until I manually set the address that the ssh server is listening on in /etc/ssh/sshd_config. Once I've connected, I seem to be kicked out at random intervals with the following error:

Write failed: Broken pipe

Using "ssh -vv" doesn't show any other information. When I'm kicked out in this manner, I cannot reconnect for another seemingly random period of time. Sometimes a few seconds, others a few minutes. If I run "netstat -nap|grep :22", I can see that my connection still exists after the write failed error. I can't seem to re-connect until that connection drops.

After one of these errors, if I hop onto the server from the console, ssh into another machine, and then attempt to ssh back into the server, everything works fine.

Using "-o TCPKeepAlive=yes" client side doesn't seem to effect anything. I've disabled both iptables and ufw on the server. AppArmor is not showing any enforced profiles and SELinux isn't installed.

My logs aren't reporting any errors and I don't have any custom configs. This is a box-stock install. Note that when I try to get back in after the broken pipe error, this is the error I get:

ssh: connect to host 172.22.50.92 port 22: Connection refused

And nmap no longer shows port 22 as being open, though netstat on the server says it's still listening on port 22.

EDIT - I'm not sure if it means anything, but I've installed KVM on these hosts and I can ssh into the guests (ubuntu server 64bit as well) without any issue.

UPDATE - I've tried purging openssh and re-installing with apt. I've also purged and installed openssh from source with no luck. traceroutes and pings overnight show no packet loss whatsoever.

YET ANOTHER UPDATE - Dell seems to think that we've got a bad motherboard in the server. Having that replaced to see if it resolves the issue.