Here are my notes how I set up SVN over SSH to an SVN server that had been set up to run SVN as a single user, "svn".

So, we have multiple users on the remote side, all logging in as "svn" on the SVN server side.
Authentication is done via a dedicated key-pair, with special options to make SVN+SSH work.

See http://svn.collab.net/repos/svn/trunk/notes/ssh-tricks for more details.

These are just my notes, the above link is authoritative.


Procedure:

1. Generate a dedicated key pair

	[SVN Client]$ ssh-keygen -f ~/.ssh/svnssh
	Generating public/private rsa key pair.
	Created directory '/home/tsalolia/.ssh'.


  

This is nifty - you can specify a remote tape drive, root@unix2:/dev/tape

Example:

unix1# tar -x -v --rsh-comand /usr/bin/ssh -f root@unix2:/dev/tape
./file1
./file2
./file3
...
unix1#

I saw on one of the news sites (Slashdot or OSNews, forget which exactly) a story about the following 10 Essential Rules for System Administrators. These are mostly pretty basic and many of them are not really SA specific. I'm not certain that "backup regularly" and "test your backups regularly" are deserving of being two separate rules; I consider that testing backups is part of the overall backup process.

One thing I thought was kind of interesting was the timing of this coming out with the number one rule being "Keep it Simple" and my first Black Belt System Administration topic "A punch is just a punch", which is not specifically about system design but about sticking with the basics.

It is trivial to set things up so you are able to select memtest86 as a boot option in GRUB:

Download the latest memtest source from http://www.memtest86.com.

Extract and follow the instructions in the README that comes with it to compile. Copy the resulting memtest.bin to /boot and edit /etc/grub.conf to have the following 3 lines:

title Memtest86
        root (hd0,0)
        kernel /boot/memtest.bin

Make sure you reboot to test.

In theory this should work with any x86 OS + bootloader. I am doing this with RHEL 4 + GRUB.

I've recently had a number of projects at work that want to mix multiple volume managers on a single server, specifically ZFS and VxVM for SAN volumes (actually, three including SVM for internal boot disk mirroring). The projects generally are for database servers, and want to use VxVM for database volumes because ZFS currently has some serious limitation on database size (limited number of devices recommended in a single zpool) and performance (single threaded checksumming, for one). However, at the same time, they want to have access to some of ZFS's features (in particular, the ability to oversubscribe filesystems, dynamic resize, snapshots and rollback) for some of the other filesystems.

Picked up this tid-bit on how to disable IPv6 (which aligns with the general sys admin philosophy of "if we are not using it, remove it or turn it off to simplify the system and increase security":

(1) Edit /etc/sysconfig/network and set NETWORKING_IPV6=no.

(2) Issue the following command as root: 'chkconfig ip6tables off'.

(3) Reboot the host machine.

Something—I'm honestly not sure what—has changed in Mac OS X Leopard in a subtle way that has totally derailed my workflow for making presentations involving code samples.

I give a lot of Keynote talks that are very heavy on code samples. For years, I've had a workflow for creating code-sample slides that's worked pretty well for me:

First, I create a directory for the slide show. Inside is my Keynote presentation, and subdirectories for ancillary materials. The relevant ones here are code-samples/ and images/.

In the code-samples/ directory, I create little files containing the code fragments. I edit them in Aquamacs Emacs (a very nice Aqua GUI for GNU Emacs) which gives me code syntax highlighting:

The AFS & Kerberos Best Practices Workshop 2008 announces the 2008
Call For Participation.

Come talk to your peers about:

* Completed projects
* Work in progress
* Theories
* Best practices
* Related research
* Updates on previous talks

or anything else of note involving AFS and/or Kerberos.

The AFS & Kerberos Best Practices Workshop is a week long conference
for the novice and the experienced. The week is filled with two
full-day classes introducing AFS and Kerberos and two and one half
days of talks by your peers and colleagues. This year's workshop will
be held May 19-23, 2008 at the New Jersey Institute of Technology in

Read an interesting discussion on the lkml list where Linus and friends talked about atime's performance impacts (http://kerneltrap.org/node/14148). Ingo phrased the problem best with:

' For every file that is read from the disk, lets do a ... write to
the disk! And, for every file that is already cached and which we
read from the cache ... do a write to the disk! '

Solutions are to mount your file systems with the noatime, nodiratime options. The only time this may cause a problem is if you have a local mail spool (the mailer will not know that new email arrived) or possibly with some backup software.