Tag Archives | Linux

PySIG Notes, 26 April 2007

By Ted Roche on April 27, 2007 in Apple Macintosh OS X, Home Page, Linux, Microsoft, OpenSource, Python, Technology

Thirteen attendees made it to the April meeting of the Python Special Interest Group, held as usual at the Amoskeag Business Incubator, Commercial Street, Manchester, NH on the fourth Thursday of the month at 7 PM.

Bill Sconce lead off the meeting with a printed agenda and a round of introductions. Several new people were welcomed to the group; a range of levels of experience with computers and specifically Python made for a good mixed crowd.

Martin LeDoux showed off homemade bookbinding of the Python tutorial. Using an HP laser and Adobe Acrobat, Martin printed duplex 2-up folded, cut, glued and bound a pretty handy homemade book. Very cool.

Shawn K. O’Shea showed off the tarfile module which allows creation, querying, extraction and manipulation of tar files (with gz or bz2 compression) from within Python. This can be a real handy way to create cross-platform installable packages that would run on OS X, Linux or Windows.

Shawn also mentioned that there was a Google API for the Google Calendar with examples in Python scripting. Someone asked what that might be used for, and I offered the LUG coordinator Nag-O-Matic as a great example of using automation with calendars.

Bill attempted an introduction to Python datatypes by creating a hierarchy from primitive to complex objects. Kent had an objection to the terminology, and countered with chapter 3 of the _library_ reference (not chapter 3 of the Python reference which Bill was using) and a vigorous discussion ensued. That’s the point of the meeting, after all. And it’s far less likely to erupt into a flamewar in person. All sides had some good points, examples and counterexamples, and most of us learned more about Python internals. Good stuff.

Kent started Kent’s Korner 4: Iterators and Generators at 9 PM, when the milk and cookies were starting to kick in, The crowd was a bit more subdued, having spent their energy harassing Bill (and heckling Ben, in abstentia). Iterators went quite quickly. Generators woke the crowd up. Bill Sconce came up with a great example of greenbar color code generator, where the boss decides there should be two reds, three greens, alternating and repeating, though he may change his mind once he sees it. Off-script, Kent took off with this example, and followed it with a discussion of parameter passing to a generator.

Kent really has a gift for shedding light on these sometimes obuse topics; his examples really helped make the functionality clear, and working through the real-world example proposed at the meeting gave us all some idea of what was involved.

Kent also mentioned that he’s using IPython (note the capitalization; guess it’s not an Apple product!) an improved interactive shell.

Meeting called at 9:44. Wow. Long meeting, but a very productive one. One of the attendees wrote to me this morning that he went home and altered some of his scripts based on what he learned at the meeting. No greater praise could we ask for.

Thanks to Bill Sconce for running the meeting, the Amoskeag Business Incubator for the facilities, Alex Hewitt for wrestling with the network, to Martin, Shawn and Kent for presenting, and to all for attending and participating.

Next meeting May 24th, topic TBA.

Postscript: Like the previous meetings, we saw examples running in Python on OS X, Windows (VMWare on the Mac, I think) and Linux. It Just Works.

Notes from MerriLUG: Christoph Doerbeck: Xen on RHEL5

By Ted Roche on April 25, 2007 in Home Page, Linux, OpenSource, Technology

Thirty people attended the April meeting of the Merrimack Valley Linux
User Group, held as usual on the third Thursday of the month at Martha’s
Exchange in Nashua.

Heather did a fine job of welcoming the large crowd, listing some
upcoming events (remember, you can always find them on
http://www.gnhlug.org), and requesting feedback on next month’s topic: a
professional graphics designer has offered to discuss what’s available
in Linux for graphics, but wants feedback on what to focus on: removing
red eye from photographs, structured drawings, etc. Let Heather know
what you’re looking to do with graphics in Linux.

Christoph was the main presenter. He is a Sales Engineer with Red Hat
and has quite a history with Linux/UNIX. He arrived with three laptops
and his own gigabit network to demonstrate several configurations of
virtualization. One laptop lacked the new hardware support and was
relegated to running VMWare. The other two machines (an HP with an AMD
chip with the magick SVx bits, and a “StinkPad” – his term, not mine! –
with the Intel VTx/VTi capabilities) were capable of using Xen with full
or para-virtualization. Christoph demonstrated both, and used the three
machines to show how a virtual machine could be transferred from one
machine to the other. Suspending and moving the VM was not successful
(it’s a demo, these things never work), but the harder one, moving a
running session was successful, demonstrated vividly with a running
video on his controlling machine streamed from a server that started on
one machine and finished on the other. Bravo!

There was also a discussion of the other alternative for virtualization,
single-kernel-image virtualization, where multiple sessions are running
in multiple zones, somewhat like a “chroot jail.” Examples of this kind
of VM include Solaris Zones, Virtuozzo and Open VZ. Members of the
audience contributed insights to some of the other projects going on,
such as the KVM (Kernel Virtual Machine) project favored by some of the
kernel developers, UML (User Mode Linux) and others.

Christoph wrapped up with a long and thorough question-and-answer
session. He then offered a completely different topic: he mastered a DVD
with menus, music, video overlays completely in Linux and had some clips
to show off. A general consensus was that he was welcome to come back at
his convenience to talk about that, too!

Thanks to Christoph for the great demo, to Heather and Jim for
organizing the meeting, to the folks at Martha’s Exchange for providing
the facilities, and to all for attending and participating.

Thunderbird 2.0 email client goes gold

By Ted Roche on April 23, 2007 in Home Page, Linux, OpenSource, Technology

DesktopLinux.com relays the news that the Thunderbird 2.0 email client goes gold. ‘Way cool. Looking forward to trying this out. I’ve been using T-bird 1.x for quite some time now, and it’s moved to becoming my primary email client, edging out Safari on the Mac and Evolution on the Linux platform. Mozillazine points out more information, including release notes and feature lists. Now, this is a Two-Point-Oh release, and my advice to the conservatives would be to hold off for the Two-Point-Oh-One version, or at least until a patch or two comes out, if you’re not comfortable installing and uninstalling mail clients. Make a backup, of course. Note that Linux clients have a funky problem with spaces in the path, so avoid spaces.

Red Hat Magazine: “Risk report: Two years of RHEL4”

By Ted Roche on April 21, 2007 in Home Page

Mark Cox writes in Red Hat Magazine, Risk report: Two years of Red Hat Enterprise Linux 4
“Red Hat® Enterprise Linux® 4 was released on February 15th, 2005. This report takes a look at the state of security for the first two years from release. We look at key metrics, specific vulnerabilities, and the most common ways users were affected by security issues. We will show some best practices that could have been used to minimise the impact of the issues, and also take a look at how the included security innovations helped.” The article not only provides some interesting information on Linux security; it also gives some insights to how the folks inside Red Hat view the security issues.

MerriLUG, 19-April: Christoph Doerbeck, Xen on RHEL5

By Ted Roche on April 9, 2007 in Home Page, Linux, Technology

A not to be missed presentation: the Merrimack Valley Linux User Group will host Christoph Doerbeck of RedHat presenting “Virtualization on Linux,” a live demo of the Xen technology running on Red Hat Enterprise Linux 5. Details here. Reservations are strongly encouraged for dinner: we’ve had a couple of huge showings at MerriLUG lately, and the staff at Martha’s have been very accomodating at getting everyone fed and on time for the meeting. I suspect this one could be SRO also.

DLSLUG notes, 5-Apr-2007: Todd Underwood discusses ZFS

By Ted Roche on April 8, 2007 in Home Page, OpenSource, Technology

Fifteen attendees made it to the April meeting of the Dartmouth Lake
Sunapee Linux User Group, held as usual in Carson Hall at the Dartmouth College campus on the first Thursday of the month.

Todd Underwood, Vice President, Operations and Professional Services at Renesys presented “ZFS: The Last Word in File Systems.” Renesys is in the business of collecting, analyzing and archiving data about what’s happening on the internet and, not surprisingly, that’s a lot of data and growing geometrically. One of Todd’s projects is to provide fast and reliable storage for the hundreds of gigabytes per day acquired and the tens of terabytes of data stored. He presented a survey of what’s out there, what his needs were, and how he reluctantly narrowed the search down to SUN Solaris and ZFS. While he had nothing but praise for ZFS, he expressed some reservations about SUN. Strong reservations.

Todd dug into the ZFS architecture. ZFS is truly amazing: disk contents are always coherent, with writes all checksummed, writes as atomic transactions, with “fancy FS internals” like IO scheduling, dynamic block sizes and prefetch queues, huge limits (128-bit data). ZFS flattens the Linux file system model of multiple layers into a single monolith, and eliminates entire classes of problems introduced by the multiple layer architecture. There is no fsck. Devices are accumulated into pools. File systems are assigned to pools. Storage addition and maintenance is fairly trivial. ZFS performance is remarkable, at disk speed (with compression, sometimes in excess of disk speed).

Todd presented the rough outlines of his storage system: $17k worth of hardware from SUN and Dell yields 7.5 terabytes of storage with nearly a gigabyte per second throughput. Todd’s disk storage challenge is solved, as the company’s demand can’t match the throughput capacity of his system, for now, and the system can be expanded with additional external storage.

As for the porting of ZFS onto other architectures, Todd expressed the opinion that running on Solaris or OpenSolaris is likely the best current solutions. Porting onto BSD is underway but not yet ready. He had heard that ZFS was ported to OS X but could not confirm (Googling ZFS OSX yields interesting results).

Todd promises to send along slides from his presentation; I’ll try to post links to them to the website.

After the main presentation, there was a good session of questions and answers. I asked a question on replication of Postgres and Todd recommended the Sequoia product.

Thanks to Todd for his thorough presentation, to Bill McGonigle for organizing the meeting, to Bill Sconce for sharing his notes with me for this post, and to all for attending and participating. Next meeting, still tentative, will be on writing a FireFox extension by Roger Trussell.

Notes from CentraLUG, 2-April-2007: Bill Stearns on LVM

By Ted Roche on April 3, 2007 in Home Page, Linux, OpenSource, Technology

A great meeting last night. The Central New Hampshire Linux User Group met at the usual place and time: The New Hampshire Technical Institute‘s Library, Room 146, 7PM on the first Monday.

I did my usual rounds of announcements, Shawn O’Shea pointed out that besides for the discuss and announce mailing lists, you can also subscribe to the lists via RSS by using one of GNHLUG’s archival sites. Add one of these to your favorite RSS readers to see the GNHLUG announcements: mail-archive.com or gmane.org

Everyone got to introduce themselves and speak a little bit about what they’re up to. I passed around a couple lists of topics and speakers from the wiki to find out what the attendees want to see for future sessions.

Bill Stearns presented “LVM: Logical Volume Management.” He explained about the basic need to expand or re-allocate disk resources without making hard partition changes, in some cases without even shutting down. We started right in on an exercise: using the loopback device and some spare space in /var/tmp, we created three loopback block devices. We assigned them as PVs (Physical Volumes) and allocated two to a Volume Group. Then, space could be allocated out of the volume group to provide the space needed. Additional PVs could be added to the VG, additional space from the VG could be allocated to a mount. We had a good discussion about the choice of filesystems and the different processing required for ext3, reiser, xfs, jfs file systems – most of which can be resized when on-line. (Bill recommended the MythTV HOWTO for a good discussion of which file system to use.

We had a good side conversation at this point about the mount tables and the significance of several flags Bill had. An intesnse discussion of ‘noatime’ – useful for hierarchical file management, but generally of little use, and a lot of disk activity, power consumption, speed decrease, and for FlashROM devicers, perhaps lifetime shortening can be avoided by adding noatime to the mount tab. Bill also had war stories about the security implications of nodev and nosuid both of which are a good idea for insertable media unless you have a specific reason for needing them.

We finished up the LVM exercise by adding the third PV to the VG and then resizing the ext3 partition to include the space. Bill took questions from the audience: one lady had just installed LVM on the Linux partition on her mainframe (!) that weekend, and wanted to know more about LVM striping. Other questions on reliability, use with RAID. Bill had some pointers for adding additional storage: use of USB2 (not USB1!) external drives (Bill hasn’t been happy with Firewire storage on Linux) or using an external storage solution (he mentioned CoRAID which uses rackable ethernet-to-ATA raw drives; Bill had one sample to play with) and handled some questions further afield, like the file defragmenter Bill has on his site.

Yet another great LUG meeting. Thanks to Bill Stearns for the great presentation (and 3-ring-bound handouts) and providing the raffle door prizes. Thanks to Bill Sconce for providing the projector and doing the note-taking during the meeting. Thanks to the New Hampshire Technical Institute for providing the facilities.

Look forward to a great presentation on OpenWRT by Ben Scott at the May 7th meeting (where you can expect him to be heckled) and another great presentation on Drupal by Seth Cohn on June 4th. Hope to see you there.

DLSLUG: April 5th: Todd Underwood: ZFS

By Ted Roche on March 30, 2007 in Home Page, Linux, OpenSource, Technology

Bill McGonigle announces the April meeting of the Dartmouth – Lake Sunapee Linux User Group. The main presentation will be “ZFS: The Last Word in Filesystems, ” presented by Todd Underwood, VP of Operations and Professional Services, Renesys Corporation. Here’s the pitch:

ZFS is the most original work in storage management in years. It offers a revolutionary, integrated approach to block device, raid, volume management and filesystem technology. We’ll take a high-level look at what makes ZFS so different from previous storage technologies and look at efforts to port ZFS to free operating systems (ZFS is available for FreeBSD and in a userland port to Linux, but the path will not be easy).

Todd has with more than 10 years experience in architecting, building, and supporting large-scale distributed systems. Before Renesys, Todd was senior vice president and chief technology officer at Oso Grande Technologies, the largest Internet service provider in New Mexico, where he was the lead consultant in the security practice. Before that, Todd was chief technology officer at Lightdart Managed Data Centers, a co-location and hosting start-up built in partnership with Public Service Company of New Mexico. As a graduate student, Todd led the effort studying high-speed networking for large-scale computer clusters at the University of New Mexico. Todd holds a B.A. from Columbia College, Columbia University and an M.S. in computer science from the University of New Mexico.

Looking forward to the meeting. Hope to see you there!

CentraLUG, 2 April 2007: Bill Stearns on Logical Volume Management

By Ted Roche on March 25, 2007 in Home Page, Linux, OpenSource, Technology

The monthly meeting of CentraLUG, the Concord/Central New Hampshire chapter of the Greater New Hampshire Linux Users Group, occurs on the first Monday of each month on the New Hampshire Institute Campus starting at 7 PM.

This month, we’ll be meeting in our usual location, Room 146 of the Library/Learning Center/Bookstore, http://www.nhti.net/nhtimap.pdf , marked as “I” on that map. Directions and maps are available on the NHTI site at http://www.nhti.edu and on the GNHLUG site at http://wiki.gnhlug.org/twiki2/bin/view/Www/DirectionsToCentraLUG. The
main meeting starts at 7 PM, with Bill Stearns presenting LVM: Logical Volume Management. Open to the public. Free admission. Tell your friends.

Bill is an authority in the field of security, an instructor for the SANS Institute and an activist in several anti-spam efforts. Visit
http://www.stearns,org for a list of some of the interesting projects he’s been working on and packages he maintains. At April’s meeting, Bill will explain the infrastructure of LVM and how to work with it. LVM is a great technology that allows you to add disk space to running systems, manage the mapping of logical and physical volumes and manipulate disk usage. With the correct choice of hardware and file systems, much of the work can be done while the systems continue to run! Bill has some practical insights into how these systems work, and can talk about some of the subtleties of why you might choose LVM-atop-RAID vs. RAID-atop-LVM. Attendees are encouraged to bring laptops: using temporary space (no need to repartition), Bill will use some loopback tricks to let you create some devices and manipulate the LVM commands – a great hands-on experience!

More details at about this meeting and the group are available at http://www.centralug.org and http://www.gnhlug.org as I learn them!

In future meetings, we are looking forward to Ben Scott demoing OpenWRT (May) and Seth Cohn showing off Drupal (June) – dates and times not yet confirmed and in flux, so stay tuned. Hope to see you there!

Notes from MerriLUG, 15-March-2007, Matt Brodeur on PGP/GPG Encryption and key-signing

By Ted Roche on March 21, 2007 in Home Page, OpenSource, Security, Technology

Nineteen attendees participated in the March meeting of the Merrimack Valley Linux User Group, MerriLUG, held as usual on the third Thursday of the month at Martha’s Exchange in Nashua, NH.

Matt Brodeur gave a presentation on GNU Privacy Guard, GPG, the Free/Open Source implementation of the Pretty Good Privacy algorithms and protocols. Matt pushed the presentation pretty quickly, as he wanted to ensure we had time for the keysigning, as well. Matt’s presentation is available from his website and that link, in turn is on the GNHLUG Wiki along with the announcements and instructions.

Following the presentation, Matt and Heather Brodeur organized the key-signing. Nearly a dozen of us had prepared and registered our PGP certificates in advance, and we read out-loud our identifying information, practicing our phonetic alphabet and confirming that I should have brought my reading glasses. Following that phase, we lined up in two queues and exchanged identification to confirm we had IDs that matched our names on the certificates. Heather was the caller for this slow-motion folk dance and kept us on task despite our urge to chat and socialize. An odd number of attendees and one additional volunteer made the sequence interesting, and we completed successfully.

Overall, I think the keysigning went quite well, by the number of signed keys I’ve received in the last week. I suspect we’ll have some feedback for Matt, too, on whether there might be some way we could make the follow-up key exchange easier. This was a lot of work, and I want to express my personal thanks to Matt and Heather for all the work. Thanks too, for all who attended and participated and asked questions, and thanks to Martha’s for providing the facilities.

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