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My last post was on gPXE (quite a while ago), and I talked about all the amazing possibilities that come from a network boot-loader with that much intelligence.
It looks like these benefits are starting to be realized in a big way. Recently, kernel.org (which hosts the Linux kernel, as well as a ton of mirrors and other projects) released boot.kernel.org. This service has you download a tiny (~500kB) image for USB, CD, or floppy. Stick it on a device and boot from it and you'll have an easy-access menu of various Linux installers, Linux live environments, and test tools.
It's still rough around the edges, and not all the installers work quite right, but it's moving along, and shows a lot of ingenuity. The various environments leverage HTTP, HTTPFS (root filesystem over HTTP), and/or iSCSI.
As an aside, if you want to use their USB image, but still have your stick be able to hold data, it's easy. Just (1) copy existing stuff off, (2) dd the image to the stick as directed on the page, and (3) add a FAT partition back to the stick. Step 3 isn't hard:
$ wget http://boot.kernel.org/gpxe_images/gpxe.usb
...
$ sudo mount /dev/sdd1 /mnt
$ mkdir backup
$ cp -r /mnt/* backup
$ sudo umount /mnt
$ sudo dd if=gpxe.usb of=/dev/sdd
435+0 records in
435+0 records out
222720 bytes (223 kB) copied, 0.159969 s, 1.4 MB/s
$ sudo fdisk /dev/sdd
Command (m for help): p
Disk /dev/sdd: 2063 MB, 2063597056 bytes
64 heads, 32 sectors/track, 1967 cylinders
Units = cylinders of 2048 * 512 = 1048576 bytes
Disk identifier: 0x00000000
Device Boot Start End Blocks Id System
/dev/sdd4 * 1 2 2032 eb BeOS fs
Command (m for help): n
Command action
e extended
p primary partition (1-4)
p
Partition number (1-4): 1
First cylinder (3-1967, default 3): (nothing)
Using default value 3
Last cylinder or +size or +sizeM or +sizeK (3-1967, default 1967): (nothing)
Using default value 1967
Command (m for help): t
Partition number (1-4): 1
Hex code (type L to list codes): b
Changed system type of partition 1 to b (W95 FAT32)
Command (m for help): p
Disk /dev/sdd: 2063 MB, 2063597056 bytes
64 heads, 32 sectors/track, 1967 cylinders
Units = cylinders of 2048 * 512 = 1048576 bytes
Disk identifier: 0x00000000
Device Boot Start End Blocks Id System
/dev/sdd1 3 1967 2012160 b W95 FAT32
/dev/sdd4 * 1 2 2032 eb BeOS fs
Partition table entries are not in disk order
Command (m for help): w
The partition table has been altered!
...
Syncing disks.
$ sudo mount /dev/sdd1 /mnt
$ cp -r backup/* /mnt
$ sudo umount /mnt
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I just read up on gPXE, which is an open source alternative to proprietary PXE bootloaders. It supports booting a variety of environments and can be flashed onto NICs or chainloaded from regular PXE.
What struck me was this: it supports HTTP download of both gPXE scripts and binary images. This means that you could set up a web server that gives out gPXE scripts based on a PHP script or other server-side code. The end result is the ability to build a cluster whose nodes boot based on the control of a simple web server. If applied to something like the NCSU VCL, it eliminates the need for disk image transfers: nodes could be configured to run a certain environment by flipping one bit on a web server instead of pushing gigabytes of disk image data.
Furthermore, this isn't just restricted to sickly old NFS boot! gPXE supports software iSCSI boot, so all modern Linux and Windows OSes can get in on the act with just a small amount of configuration.
If I had more time, I'd love to apply this kind of deployment on our research clusters. Just putting the selection of Linux kernels in a centralized place would be a big help, even if we still mount the local disk as root!
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Ars Technica is carrying an interview with Russ Daniels, HP's CTO and VP of Cloud Services Strategy. He discusses a practical definition for cloud computing and distinguishes it from utility computing.
Part 1
Part 2
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We've been interested in applying power-aware techniques to virtualized compute grids, including so-called "cloud computing" grids. A key part of this work is dynamically scaling the amount of compute capacity based on load, which in some cases can be done automatically.
This article presents an opposing viewpoint and points out some ways in which automatically-driven dynamic resizing of compute resources might be a bad thing. I think the author goes a bit to far in throwing out automatic scaling entirely, but he does raise several valid points, especially with respect to security and the possibility of DDOS attacks.
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I found an article that shows interesting analysis of power savings in a data center. In a 5,000-square-foot data center, a 1-watt reduction at the server-component level (processor, memory, hard disk, etc.) results in an additional 1.84-watt savings in the power supply, power distribution system, UPS system, cooling system, etc. Consequently, every watt of savings that can be achieved on the processor level creates approximately 2.84 watts of savings for the overall facility.
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Tom's Hardware tested the power and performance of current Solid State Disks (SSDs) both in terms of performance and power. While the performance numbers were as expected, it turns out that the flash based drives' energy utilization is no better than a traditional 7200 RPM hard disk for a practical workload based on the MobileMark benchmark. The authors contend that this is because hard disks reach their maximum power draw only when seeking, whereas flash storage uses full power during any IO activity.
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Ubuntu 8.04 was released earlier this week. You can get it from one of the official mirrors or from our unofficial mirror. This is a "Long Term Support" (LTS) release, meaning that updates will be available for 3 years on the desktop and 5 years for servers.
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The Barcelona (aka "K10") microarchitecture is the latest design from AMD for both the server and desktop markets. The Phenom is the quad-core desktop variant, the Athlon X2 series includes the dual-core variant, and the 23xx and 83xx Opterons are the quad-core server varient.
The key changes over the previous line are covered in brief here and in greater detail here. Most of the interesting features require the use of an upgraded CPU socket denoted by a "+" (e.g. Socket AM2+ or Socket F+), though the CPU will work in non-plus sockets on current motherboards. Some of the "plus socket" features are:
• Separated voltage planes allow the CPU to have a different voltage/frequency for each core and the northbridge.
• HyperTransport 3.0, allowing greater bus bandwidth, including support for DDR2-1066.
In addition, the Barcelona introduces a shared L3 cache, which should have a major impact on HPC applications.
One major issue, however, is an L3 TLB bug present in the first generation of this architecture. This problem can be solved by disabling part of the L3 TLB system in the BIOS or via software (with a 10% performance penalty), or using a unique Linux patch to route around the problem with limited slowdown (but the patch is not intended for production use). See the Phenom wikipedia article for details.
In short, while Intel retains the upper hand in horsepower now, the AMD Barcelona design seems to sport many of the features predicted for future system design.
More information:
Wikipedia's Barcelona article covers the architecture in depth.
Anandtech benchmarking puts the chip through its paces.
To find a Barcelona-based chip, see Wikipedia:
• Phenom quad-cores
• Barcelona-based dual-core Athlons (scroll to "Phenom based")
• Barcelona-based quad-core Opterons (23xx and 83xx)
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This recent "Innovations" article highlights "utility computing", the idea that virtualization, shared storage, and other technologies will come together to commoditize business computing.
While I agree with the general idea, the author predicts that this will marginalize IT as a field, which seems counter-intuitive. While this kind of computing does allow fewer people to manage more systems, it does make that management that much more complicated. Further, IT has always been about helping users as much as maintaining infrastructure. So I don't see the general IT realm getting eaten by other fields, but rather splintering into specialists in networking, storage, (virtual) system administration, support, etc.
Finally, I found this quote pretty funny:
Teenagers entering higher education today are already skilled at building personal application spaces on Facebook using software modules. It’s a small step to apply those principles to business applications.
"A small step" to go from facebook to a crucial business application? Seems unlikely.
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