Issue #10 August 2005

Ask Shadowman

Shadowman got a lot of pretty technical questions in the old virtual mailbox this month. It's a long hot summer, and so Shadowman is ready to dispense with the usual banter and jump right in, with a tall glass of lemonade, a stack of manuals, and a good search engine at the ready.

Let's get started.

Got a question that you'd like Shadowman to answer? Ask him.

Alex asked:

I've got some AIX/HP-UX/Solaris sysadmins around my office that complain that the Red Hat Enterprise Linux platform is weak because it does not support the resizing of mounted filesystems. I did some basic google searching and it appears they're correct, to expand an ext3 filesystem you have to unmount it. Is support for online resizing going to be added to ext3 soon? Will Red Hat Enterprise Linux ever support it?

To which Shadowman replies:

First, for everything you could possibly want to know about the latest and greatest happenings in ext3, Shadowman recommends that you check out the paper presented by Mingming Cao at the 2005 Ottawa Linux Symposium just last month.

Online resizing support for ext3 hit the mainline kernel in 2.6.10 last November or thereabouts. The tools to take advantage of this support are in e2fsprogs 1.36.

None of this code is in Red Hat Enterprise Linux 4 (kernel 2.6.9 and e2fsprogs 1.35), but all of it is in Fedora Core 4 (kernel 2.6.11 and e2fsprogs 1.37). Therefore, it's an exceedingly good bet that online resizing will be available, and very well baked, in Enterprise Linux 5.

Nick asked:

I'd like to use Red Hat Enterprise Linux 4 exclusively at work but the one thing I'm missing is the ability to access my mail from the corporate Exchange server. Any ideas?

To which Shadowman replies:

So long as you're using Evolution as your mail client, you should be perfectly happy using Evolution Connector, which ships with Red Hat Enterprise Linux 4. Evolution Connector allows Evolution to act as a Microsoft Exchange client. If you didn't install it when you installed your system, it should be as simple as:

up2date evolution-connector

If you're using mutt, Shadowman can't help you.

Dan asked:

I am trying to set up a diskless network installation environment using PXE boot and Kickstart to install Linux. So far, I'm able to PXE boot using pxelinux.0 and I can launch into the Linux setup. But I am unable to get the system to use the ks.cfg file that I created. I'm using a Broadcom TG3 NIC and my DHCP server is Win2K, not Linux. How can I get my setup to use my Kickstart file?

To which Shadowman replies:

There's a bunch of variables in play here, Dan, and you're not giving Shadowman a lot to work with. Looks like you've got a bunch of the pieces right or you wouldn't be booting a Linux image at all—only Shadowman doesn't have enough info to know which pieces those are. Could be that you've got a screwy tftp server; could be that you've crossed up your pxelinux config files; could be that you're not even talking to the pxe/dhcp/bootp server you think you're talking to. So Shadowman's gonna give you a little bit of friendly advice:

Read until you go crosseyed, and then hack until your fingers bleed.

Ah, but read what? There's the question.

Shadowman says, go read H. Peter Anvin's pxelinux FAQ over and over and over. Print it out and take it to the can with you. And have it handy when you're working on this stuff.

And then when you've done that, go and read Alf Wachsmann's great document, How to Install Red Hat Linux via PXE and Kickstart to understand what you're trying to do from end to end. It's a little dated, but the principles are correct, and it's important to understand what you're doing at every step of the way so you can figure out which step is broken.

Basically, once you're finding a boot image, getting a box to kickstart with pxe properly is usually a matter of making sure that you've got the right pxelinux config file to describe how to boot that image. The idea is to set up that pxeconfig file to pass a specific kickstart argument (ks=protocol:/my/kickstart/tree/ks.cfg) to the bootloader, just as if you were booting manually and typing it in at the keyboard.

So in short: read, hack, read, hack, best of luck in your future endeavors.

John wrote in to the Editor:

I question the Shadowman articles. To the reader they seem fake, that someone asks these questions.

To which Shadowman replies:

Oh, ye of little faith, John. Shadowman can assure you that the emails he receives are completely genuine. Shadowman receives 25-50 emails a month, or more if he says something particularly stupid, and cherry-picks the most interesting ones. Some of them may be slightly edited, as not all of Shadowman's fans are gifted in the arts of spelling and grammar, but the substance of these letters are exactly as Shadowman presents them.

Shadowman doesn't do fake, baby. Shadowman represents, now and forever. Shadowman is automatic for the people.

Confidential to Steve:

Maybe this tale of woe will give you something to go on. Maybe not.