March 1, 2010
(PICC is a regional sysadmin conference to be held in central NJ on May
7-8, 2010. I’m on the planning committee. http://picconf.org)
Today is the deadline for proposals for papers, talks, and such.
We’re a little low on submissions so I’d like to make one more “beg”. We’d love to have a talk about PHP for sysadmins, something fun you’ve done with Arduino, your favorite JS library, a walk-through on setting up Google Apps. Demo your favorite open source project, or propose a panel of people to talk about something you find interesting (I can help find others for your panel). It is an excellent way to spread the word about a project you are involved with.
We’ve tried to make the proposal process really easy. Just send your
contact info and topic plus a 1-2 paragraph description to
submissions@lopsanj.org
For more info, contact me and/or view:
http://lopsanj.org/events/picc10/cfp
BTW, today is the deadline but we can grant extensions to anyone that writes and asks.
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March 1, 2010
This is flashback week, and today I’m including a HOWTO that I originally wrote in June of 2008 called “HOWTO: Racks and Rackmounting”. I had decided that no one was focusing on the physical aspect of system administration, even though most of us still have to deal with it. So I put together this information in the hopes that it would be useful.
Since it was originally published, it’s been viewed over 2,000 times and is still in the top 10 blog entries, which means that still, not enough people are covering the physical infrastructure aspect of system administration.
Enjoy!
I’m going to start a special feature on Fridays. It’s going to be sharing the sorts of tips that systems admins need to know, but can’t learn in a book. There are so many things that you learn on the job, figure out on your own, or run across on the net which make you realize that you’ve been doing something wrong for years. Sometimes you learn about things that you might have had no clue about. For instance, I just found out that you can do snapshots with
LVM
Anyway, this Friday, I’m going to be showing you what I know about server racks.
I started out on a network that had a bunch of tower machines on industrial shelves; the sort you pick up at Harbor Freight or Big Lots. When we moved to racks and rackmount servers, it was like a whole new world.
The first difference is form-factor. Tower servers are usually rated by the “tower” descriptive. Full tower, half tower, mid-tower. Rack Servers are sized according to ‘U’s, short for “Rack Unit”. It’s equivalent to 1 3/4 inches, so a 2U server is 3.5” tall. The standard width for rackmount servers is 19” across. Server racks vary in depth, between 23 and 36”, with deeper being more common.
Instead of shelves for each server, rack hardware holds the server in place, usually suspended by the sides of the machine. They allow the server to slide in and out, sometimes permitting the removal of the server’s cover to access internal components. Different manufacturers have different locking mechanisms to keep the servers in place, but all rack kits I’ve seen come with instructions.
To anchor the rack hardware (also known as rails) to the rack itself, a variety of methods have been implemented. There are two main types of rack. Round hole racks, seen at the left, require a special type of rack hardware. Much more common is square hole racks, which require the use of rack nuts. The rack nuts act as screw anchors to keep the hardware in place. Some server manufacturers have created specific rack hardware that fits most square hole racks, and don’t require the use of rack nuts. Dell’s “rapidrail” system is one with which I’m very familiar. Typically you get the option of which rail system you want when you purchase the system.
Installing the rack nuts is made easier with a specialized tool. I call it the “rack tool”, but I’m sure there’s another name. The rack nut is place with the inside edge clip in place, through the hole. The tool is inserted through the hole, grabs the outside clip, and then you pull the hook towards you. This pulls the outside clip to the front of the hole, securing the nut in place.
A typical server will require eight nuts, usually at the top and bottom of each rack unit, on the right and left sides, front and back. Each rack unit consists of three square holes, and a rack nut is put in the top and bottom of both the right and the left sides. Several pieces of networking equipment have space for four screws, but I’ve found that they stay in place fine with two. I can’t really recommend it for other people, but if you’re low on rack nuts, it’s better than letting the switches just sit there (and it almost always seems like you have fewer rack nuts than you need once your rack starts growing). If you only use two screws to hold in your n
etworking equipment, make sure it’s the bottom two. The center of gravity of a rackmount switch is always behind the screws, so if the top screws hold it up, the bottom has a tendency to swing out, and that’s not good for your rack or your hardware.
While I’m on the subject of swtches, let me give you this piece of advice. Mount your switches in the rear of the rack. It seems obvious, but you have no idea how many people mount them on the front in the beginning because “it looks cooler” and then regrets it when they continually have to run cable through the rack to the front.
Once your rack starts to fill out, heat will become an issue. When you align your rack for your air conditioner, another bit of common sense that’s frequently ignored. Air goes into the servers through the front, and hot air leaves through the back. This means that when you cool your rack, you should point the AC towards the front of your rack, not the back.
Air comes in here… And leaves back here
It’s probably not a stranger to anyone who’s used a computer, but the cables seem to have a mind of their own, and nowhere is it more apparent than a reasonably full server rack. Many higher-end solutions provide built-in cable management features, such as in-cabinet runs for power cables or network cables, swing arms for cabling runs, and various places to put tie-downs.
There is no end-all-be-all advice to rack management, but there are some tips I can give you from my own experience.
Use Velcro for cabling that is likely to change in the next year. Permanent or semi-permanent cabling can deal with plastic zipties, as long as they aren’t pulled too tight, but anytime you see yourself having to clip zipties to get access to a cable, use Velcro. It’s far too easy to accidentally snip an Ethernet cable in addition to the ziptie.
Your rackmount servers will, in many cases, come with cable management arms. Ignore them. Melt them down or throw them away, but all they’ve ever done for me is block heat from escaping out the back.
Label everything. That includes both ends of the wires. Do this for all wires, even power cables (or especially power cables). Write down which servers are powered by which power sources.
If you have a lot of similar servers, label the back of the servers too. Pulling the wrong wire from the wrong server is not my idea of a good time.
Keep your rack tool in a convenient, conspicuous spot. I ran a zip tie through the side of the rack, and hang mine there.
(Some photos were courtesy of Ronnie Garciavia Flickr)
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March 1, 2010
So, this coming May 14th will be Standalone Sysadmin’s 2nd Blogiversary, meaning it’s been around since 2008. When I first started it, I had a lot more time to write in it than I do now, which means that I wrote more entries, and because I was pretty much bursting with information that I’d never told anyone, a lot of the things that I wrote were probably more useful than the stuff that I put out on a daily basis.
I switched this blog from Blogger to its own domain in July of 2009, and even though I did import all of my old articles (they’re available in the convenient sidebar over there —–>) it takes extra effort to go back and read old entries (not to mention that there are over 400 of them! Yikes).
So this leads to the inefficient situation we have before us. I wrote a lot of (what I hope is) useful stuff, but I wrote it before the blog got popular, and most of you have never seen it. This week, I’m going to try to fix that.
I’m taking a week off of writing actual blog entries (honestly? not much of a change, I know. Sorry about that) to post some old stuff that I suspect very few of you were around for. I’ve also encouraged some other bloggers to do the same, because I’d love to see some of their great old blog entries that are still useful today. I know they’re out there, but none of us have time to weed through the histories to find them. This week is about bringing them into the open.
So please forgive me if this week seems like a flashback episode on your favorite sitcom, but I sincerely hope that you find the posts useful and informative. Thanks!
(Incidentally, while looking for the picture of the t-rex included above, I found this. wow!)
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February 27, 2010
A few hours ago, the coastline of Chili suffered an 8.8 magnitude earthquake. This earthquake was powerful enough, and in the right location, to generate a large destructive tsunami. Apparently the Juan Fernandez islands, off the coast, were hit with a large tsunami already, although I seriously doubt the height mentioned in those headlines.
In any event, if you are on the pacific coast, go inland and uphill. It may be for nothing, but it may not be, too. Remember that loss of property is inevitable, but loss of life isn’t. Protect yourself and your family.
Also, know the warning sign of a tsunami. A waterline that recedes quickly means a tsunami is imminent. According to reports from the Boxing Day tsunami, human curiosity drove people to investigate the lowered waterline, which was responsible for many, many deaths. If the waterline recedes rapidly, run away. Run uphill. The reports from Juan Fernandez were of 40 meter waves, which sounds too high, but if that really is the case, that’s around the same height as a 13 story building. Don’t take chances.
Go inland if you’re in the affected area.
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February 24, 2010
I’ve mentioned the Professional IT Community Conference (PICC) before, but now the fun has really started.
Registration is open and the speakers have been announced!
The cost is low, and the benefits are huge. I know from Google Analytics that this site receives hits from over 500 unique users in the region of this conference, every month. We don’t have that kind of space at the conference. It’s going to sell out at some point, so make sure that you talk to your boss now about attending. We’ve even drafted a letter to help convince them that it’s worth your time and their money.
It isn’t often that you get a local conference with speakers like Tom Limoncelli and David Blank-Edelman, not to mention Eben M Haber from the IBM research lab in Almaden, CA! This conference is going to get you the biggest bang for your buck out there.
What I’d like you to do is to help me get the word out. Please. Not everyone reading this is in the NJ/NY/PA/CT/DE area. For those of you who aren’t, please tell other people. Follow us on twitter at @picconf, email the site (http://www.picconf.org) to anyone you know in the area who might be interested, tell user groups about it, heck, we’ve even got a facebook page that you can become a fan of.
This is absolutely a grass-roots kind of effort. We have a very small advertising budget, so I want to use that as intelligently as possible. That means getting your help for the initial waves, and to spread it by word of mouth, by email, link, tweet, IM, and whatever else you’ve got.
A very big thank you to every one of you out there who reads this blog and supports me. I appreciate all of you.
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February 22, 2010
I get the feeling that this will be making the sysadmin-blog rounds 
Today’s XKCD is excellent, and already has a huge following from the sysadmins on twitter.
The alt-text is:
The weird sense of duty really good sysadmins have can border on the sociopathic, but it’s nice to know that it stands between the forces of darkness and your cat blog’s servers.
He’s right, of course. Sysadmins in general can develop a hero complex.
It’s a complex topic, but the smartest people in systems administration today (read: not me) have been vocal that sysadmin heroism should be discouraged. I can agree with that, to a point. We should never rely on heroism to save the day, because that means our designs have failed. When we stop believing in miracles and start relying on them, we have made bad design decisions and the reliability of our network will suffer.
On the other hand, there are sometimes events which happen that are beyond our control, and it’s up to us to make it right. In those cases, there’s no rule or mandate that says “you – sysadmin: go above and beyond the call of duty and be a hero!” I think it’s more our mental alignment that says “It’s my job to make sure that things work. In order to make things work, I’ve got to climb on top of the roof in the middle of a blizzard and restart the generator” (something my boss has done multiple times, and I’m sure some of you have as well). It’s just the way it works. We think logically, if the job needs done, and it’s our job to do it, then we need to do the job. The peripheral variables are unimportant.
I think the comic is hilarious, but like most Mission Impossible / Jack Bauer / Die Hard scenarios, it’s a rare event. Don’t go take ju-jitsu just in case someone cuts your network cables. Have a redundant infrastructure so that it doesn’t matter if they get cut.
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