LINUX NEWS
http://www.Cramsession.com
October 24, 2002 -- Issue #104TABLE OF CONTENTS
1) Sean’s Notes
2) Linux News
Would You Like Linux With That?
Mandrake 9.0 Review
Automating Manufacturing Processes
Linux IP Telephony to be Demonstrated3) Linux Resources
In a Jiffy
Linux Basics
New DNS and BIND Book
How to Really Screw Up a Linux Installation
Creating a Chroot Jail4) App o’ the Week
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1) Sean’s Notes
Every so often I’ll run into a story that gets me into the disaster recovery frame of mind. This time around, a water main broke outside the wall of a company’s data centre. The resulting water jet broke a hole in the wall, and demolished much of their operation. However, they had prepared for such a disaster, and were able to stay in business.
http://media.corporate-ir.net/media_files/nsd/tess/consumermail.htm l
Take it with a grain of salt, some of this company’s business seems to be supply chain, so it’s a feather in their hat that their products were so versatile.
A water main break? Who would have guessed? Often, we plan for a power supply failing, maybe our ISP falling over, but rarely do we think “what if this office weren’t here tomorrow?”
This article also sparked discussion on the NANOG mailing list:
http://www.cctec.com/maillists/nanog/current/msg00441.html
Some of the messages in the thread talk about other water-based threats. If you’re in a multi-level building, and there is a fire in the floor above, where is the water from the sprinklers going to go? Or, worse, you have a fire of your own and have to shut down your servers?
Before we rush out and throw money at this problem, it’s probably good to do a risk assessment. The questions I’d be asking are:
- What is the business’s tolerance to outage? Minutes? Hours? Days?
Sometimes it’s easy to quantify an outage in terms of $/hr, but sometimes it’s not as easy, such as dealing with human lives.
- What services are essential to offer, and how will they be offered? What sort of service level is expected?
If your business is taking orders over the web, is it acceptable to have customers phone in orders while you’re recovering? If your business has to run on computers, is a delay in service acceptable? If a task once responded instantly when 5000 users used it, but took 10 seconds when you were in disaster mode, is this OK?
- How does the application fail? What does it need to run?
In the networking world, failover is pretty straightforward. Networks can be moved around the globe in seconds or minutes. If the application that drives the business caves in because it doesn’t have the data it needs, technology can’t help it.
These questions aren’t technical questions, they’re business questions, which is good, because disaster recovery is a business problem.
What are business problems doing in a Linux newsletter? Well, the fact of the matter is that our skills as systems and network admins are leveraged by the business to solve their problems. All the Linux skills in the world won’t help if you can’t apply them to the problem. Sometimes we just have to step back from the details of what we’re doing and look at the big picture.
I liken this disaster recovery planning to insurance. The business is spending money on equipment and people to hedge off any losses in the event that something awful happened to the primary data centre. Part of the planning might end up saying that you’ll just have to accept the risk. Maybe you realize that for N dollars you can guard against many risks, but to really take care of every contingency will require 10*N dollars. At that point, it’s up to management to authorize the extra spending, or say “we’ve done all we can”. However, one of our jobs as admins is to highlight the risks, and discuss possible ways of mitigating it. You’ll find that even though you can’t solve a particular problem, discussing it and realizing that you can’t solve it is a whole lot better than being left in the dark.
As a closing note, one excellent example of a fault tolerant system is the global DNS. Did you know a massive DOS attack was launched this week against most of the root servers? I didn’t until I read it online, because everything worked like normal. The thirteen root servers are spread around the globe, each able to take a 300% load. Even with most of them out of commission, the Internet can still go, because the data on the root servers is cached on the top level domain servers. This will not be feasible in every situation, but DNS shows that it can be done. Not bad for something built 20-odd years ago, eh?
Long live the Penguin,
Sean swalberg@cramsession.com
2) Linux News
Would You Like Linux With That?
Burger King has announced that their POS systems in Puerto Rico will be Linux-based. The application is all web based, making Linux the natural choice. This article goes over some of the technology and hardware involved.
http://www.linuxdevices.com/news/NS8708456183.html
Mandrake 9.0 Review
ExtremeTech takes a look at Mandrake 9.0. Some good stuff here, a screenshot or two, but also a description of the differences between all the different offerings available from Mandrake.
http://www.extremetech.com/article2/0,3973,640914,00.asp
Automating Manufacturing Processes
Linux is finding its way into more than just your desktops and servers. Manufacturing processes, once the domain of programmable logic controllers (PLCs) are starting to benefit from the Penguin, too.
http://www.linuxplanet.com/linuxplanet/reports/4487/1/
Linux IP Telephony to be Demonstrated
Bayonne is a project to let Linux play with telephony cards, in the hopes of creating a PBX or IVR environment. Right now, this is the domain of big, expensive hardware, so this project will certainly have a market when it is successful.
http://newsforge.com/newsforge/02/10/20/1755217.shtml?tid
3) Linux Resources
In a Jiffy
The fundamental unit of time in Linux is the jiffy, which currently stands at 10ms. Everything hinges on it, especially task scheduling. The 2.5 kernels allowed this number to be changed. The code to do so was ported back to 2.4, and the author answers some questions about the patch in an easy-to- understand manner.
http://kerneltrap.org/node.php?idF4
Linux Basics
This introductory document takes the reader through many common tasks that occur on a Linux box. Though the domain name would suggest it’s for Debian users, the instructions aren’t very distribution-specific.
http://www.aboutdebian.com/linux.htm
New DNS and BIND Book
O’Reilly is releasing a new book on DNS and BIND. Their first book on this subject was excellent, and I’m looking forward to seeing this one. Part of the promotion behind the release of this book is the posting of some excerpts. Well worth a read if you’re into BIND.
http://www.oreillynet.com/pub/a/network/excerpt/dnsbindcook_ch05/in dex.html
How to Really Screw Up a Linux Installation
Here are the chronicles of Mary Robinson, a frequent contributer to Cramsession’s content. She installed Linux a while ago, and wrote up some of the problems she encountered. I remember working through some of this with her, and believe me, it’s better to learn from her mistakes than go through that again!
http://infocenter.cramsession.com/techlibrary/gethtml.asp?ID76
Creating a Chroot Jail
Here are some generic instructions to keep in mind whenever you’re looking at creating a chroot jail. The idea behind the jail is that you can run an application inside of it, and if it is compromised, the attacker can’t get out to the rest of your system.
http://www.networkdweebs.com/chroot.html
4) App o’ the Week
Now here is a cool utility! If you have a command that involves pipes, it’ll report on the speed and progress. Very interesting statistics!
http://www.ivarch.com/programs/pv.shtml
(C) 2002 BrainBuzz.com, Inc. All Rights Reserved.
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