Archive for the ‘Linux’ Category

working with initrd.img files

Thursday, May 28th, 2009

You may have occasion to edit the contents of an initrd.img file. If so, here is how:

Extract the contents of the image

gunzip < your-initrd.img | cpio -i --make-directories

Now make your edits and then repackage the initrd

find . | cpio -o -H newc | gzip -9 > your-new-initrd.img

sata_mv timeouts fixed

Wednesday, April 8th, 2009

Well isnt this a happy day for owners of the Supermicro 8-Port SATA Card AOC-SAT2-MV8. It appears a long standing issue with port timeouts has been fixed.

See the lkml.org mailing list post here

… and the townspeople rejoiced :)

diskless booting with PXE and NFS

Sunday, February 15th, 2009

For a long time now I’ve wanted to set up all my mythfrontends to be diskless nodes that boot via PXE using an NFS share as their root filesystem. I finally got around to doing this. I was even able to just migrate my existing installations directly into the PXE boot environment. Here is how I accomplished it…

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How to mount partitioned disk image files

Wednesday, October 1st, 2008

Mounting unpartitioned disk image files in Linux is easy. You just execute ‘mount -o loop disk.img /mnt’ right?

Well, if your disk image file happens to contain partitions its a little bit trickier. Here is what you need to do:

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Performance testing Linux software RAID

Friday, September 12th, 2008

With the forthcoming release of Debian Lenny it happened to be a good time for me to re-evaluate my decision to use one monster RAID6 device to back all my iSCSI targets. I ran a semi-formal test on different disk configurations for software raid and came up with these results…

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Coraid Odyssey: Part 6 (sata_mv hotplug)

Tuesday, April 29th, 2008

The final installment of our coraid adventure and not really much to say other than this: it works! Hotplug support is working as of kernel 2.6.25-git11 and appears to function as it should.

Thanks go to Mark Lord, Marvell Corporation, EMC Corporation and Red Hat, Inc. for the coding magic.

Coraid Odyssey: Part 5 (AoE vs iSCSI)

Wednesday, April 16th, 2008

The next phase of this project is choosing AoE or iSCSI. The debate on the relative merits of each protocol continues to rage on the Internet but in my particular case the criteria are pretty simple; which one performs better without causing excessive system load? Just from reading about the two protocols I am already leaning toward iSCSI for the simple fact that I can use all my TCP/IP management tools (routing, NAT, firewalling, etc.) on every iSCSI device. The only (potential) drawback is CPU load on the involved systems since it has to calculate TCP checksums for all those packets. Yes, there are many, many other advantages of one protocol over the other. No, they don’t matter to me in this scenario :-) So here we go!

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Convert firmware images from .bin to .trx

Sunday, November 4th, 2007

You may on occasion have a need to convert .bin firmware images such as those used to flash linksys based devices into .trx formatted images that can be accepted by OpenWRT. Its actually quite easy to do:

dd if=image.bin of=image.trx bs=32 skip=1

That will strip the first 32 bytes off the image, thus making it a valid .trx formatted firmware image file. Neat, huh?

Tar and Restore Files Over SSH

Thursday, August 16th, 2007

This will be pretty obvious to seasoned *nix admins but it’s possible to tar/gz/bzip files over an ssh connection onto a remote file system. Read on to find out how…

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PowerPC Arch Added to Backports

Thursday, July 12th, 2007

I have added powerpc to my backports repository in addition to the already included i386 and amd64 archictectures. See this post for more information.

Enjoy!