ahanson's questions

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How do I recover a RHEL 4.3 server from bad permissions set over the entire filesystem?

Is there any way to restore the default ownership of a CentOS filesystem after an accidental chown -R user:group /* ?

Before I go and reinstall, I thought I'd ask and perhaps save some time. I'm in the process of setting up a new dev machine (thankfully not prod) and typed too fast or missed the . key or something. I tried to cancel as soon as I caught it but all my /bin /boot /dev etc had already been changed.

Is there hope, or just reinstall and be happy it wasn't a production machine?

I'm working on getting some servers running in the EC2 environment and I'm noticing some errors with ntpd trying to sync (using CentOS).

I was reading on this site and the impression I get is that I don't need to run ntpd since EC2 is Xen and the host takes care of the time for the virtual servers.
http://support.ntp.org/bin/view/Support/KnownOsIssues

Is this accurate or do I need to figure out how to get around the error I'm having?
cap_set_proc() failed to drop root privileges
It looks like it involves building a new kernel and other stuff I'd rather not do if I don't have to.

I've recently been moving our instances to EBS instances (CentOS) and still have a bit of confusion on what's happening when I "stop" and instance. I have some of my services with runlevels 345 on but when I start a stopped instance the services don't start. What's actually happening when I issue a stop command to the instance, and how do I get my services to start automatically when I start the instance up again?

We've been moving servers to EC2 lately and I ran into an issue recently involving locales. We use a script to build an AMI from scratch that is largely based on a simplified RightScale script. However, we recently worked on an international project and I discovered that the locale was not set during the scripted install (issuing locale at the command line results in posix). It appear there is no i18n file by default. However, checking a development server that I installed locally (via GUI) the i18n file exists.

What package(s) do I need to install and which program can I run (command line) to configure this during the scripted install?

We're running the current version of CentOS. (5.4)

We've had a server (CentOS) running in EC2 for a few months. It had been going pretty smoothly until today when we got an alarm that the server was unavailable (HTTP service couldn't be reached). So I tried SSHing into the box but that timed out as well. I logged into the EC2 console and it said the instance was running and there wasn't anything in the system log. One odd thing I noticed is that even though we have an Elastic IP attached to it (which shows in the Elastic IP management area), the instance detail is not showing that there is an EIP associated with the instance.

I looked through the message log and the last thing I see around the time we got our alert was the dhclient renewed the lease. I'm guessing there may have been some sort of issue with the networking.

How might I check if that was the problem, or if there were any other issues that may have caused our instance to stop responding?

I'm trying to write an install script for my Amazon servers and I'm getting stuck on some environment variable issues. I have a set of scripts to configure things and some of them depend on environment variables that I create in profile.d scripts. I create the profile.d script (or copy it over) and need to use the variables it sets in scripts that run later (without logging out and back in).

Is there a way to load these (in a script) so future scripts take advantage of them?

In the script after I create the file I tried:
source /etc/profile.d/scriptname.sh
and
. /etc/profile.d/scriptname.sh
but it only sets the environment variable for the duration of the currently running script, so any other script that gets run later can't use the values being set. How do I get them to get set for the session instead of the script?

I have one master script that calls a series of small scripts to do all the configurations.

We're using ext3 right now for our EBS file systems and I was wondering if there would be any problems with the following scenario for expanding the size.

1. Create EBS initial size 2GB (ebs1)
2. Snapshot EBS (s1)
3. Create 10GB EBS (ebs2) from snapshot (s1)

Will this corrupt the file system? Will the ext3 file system automatically handle this situation? Likewise, will decreasing the size, using the same method, cause any problems (assuming the space is still sufficient for the data)?

I have successfully done this in the EC2 environment but since I'm currently using very little data I'm not sure if I've caused any problems.

Would running fsck find issues like this?

Part of my migration strategy of moving to Amazon EC2 for our servers involves making use of symlinks to keep installs and files in their 'standard' locations on the servers but the actual storage of logs files, data, etc. on EBS storage, for persistence. After the server starts up, I run scripts that create symlinks to the config files and data stored on the EBS to 'convert' the server to the setup I need.

Since I'm not a true Linux sysadmin (small company developer), I'm nervous about any sort of gotchas I might be unaware of by using symlinks. Things like breaking software packages or other difficulties where the applications might not like utilizing symlinks are what I'm concerned about.

Are there any common gotchas using symlinks or are they pretty foolproof?

My company is moving our hosting to Amazon and I'm working though all the migration issues. It has been quite a challenge transitioning from physical hardware to transient virtual machines.

One of the last challenges is figuring out how to manage our EBS's and snapshots. Since their is no way currently to name them descriptively or add meaning, I'm wondering how admins are managing their resources. It's not too much of a problem with one or two servers, but how are those running multiple servers handling things. Is everyone using third party tools (like RightScale/Scalr) when they get over a handful of servers? Or are you maintaining wikis or other ancillary documentation?

I've grown quite fond of HTTP reverse proxies in our development environment and found the DNS based virtual host reverse proxy quite useful. Having only one port (and the standard one) open on the firewall makes it much easier for management.

I'd like to find something similar to do SSH connections but haven't had much luck. I'd prefer not to simply use SSH tunneling since that requires opening port ranges other than the standard. Is there anything out there that can do this?

Could HAProxy do this?