Older blog entries for mikal (starting at number 870)

Wow, qemu-img is fast

I wanted to determine if its worth putting ephemeral images into the libvirt cache at all. How expensive are these images to create? They don't need to come from the image service, so it can't be too bad, right? It turns out that qemu-img is very very fast at creating these images, based on the very small data set of my laptop with an ext4 file system...

    mikal@x220:/data/temp$ time qemu-img create -f raw disk 10g
    Formatting 'disk', fmt=raw size=10737418240 
    real	0m0.315s
    user	0m0.000s
    sys	0m0.004s
    mikal@x220:/data/temp$ time qemu-img create -f raw disk 100g
    Formatting 'disk', fmt=raw size=107374182400 
    real	0m0.004s
    user	0m0.000s
    sys	0m0.000s

    Perhaps this is because I am using ext4, which does funky extents things when allocating blocks. However, the only ext3 file system I could find at my place is my off site backup disks, which are USB3 attached instead of the SATA2 that my laptop uses. Here's the number from there:

Slow git review uploads?

jeblair was kind enough to help me debug my problem with slow "git review" uploads for Openstack projects just now. It turns out that part of my standard configuration for ssh is to enable ControlMaster and ControlPersist. I mostly do this because the machines I use at Canonical are a very long way away from my home in Australia, and its nice to have slightly faster connections when you ssh to a machine. However, gerrit is incompatible with these options as best as we can tell.

So, if your git reviews are taking 10 to 20 minutes to upload like mine were, check that you're not using persistent connections. Excluding review.openstack.org from that part of my configuration has made a massive difference to the speed of uploads for me.

Tags for this post: openstack git review gerrit ssh voices
Related posts: More reviews; Book reviews; Contact details for the Canberra LCA 2013 bid; Working on review comments for Chapters 2, 3 and 4 tonight; A ssh quickie; Review; LCA 2013 bid process opens - Canberra at the ready!; Andrew's SSH filtering causes me pain; Further adventures with base images in OpenStack; Twisted conch; The Wild Palms Hotel; The mechanics of bidding for LCA; Status of the book; Are you in a LUG? Do you want some promotional materials for LCA 2013?; Announcement video; linux.conf.au Returns to Canberra in 2013; Canberra officially expresses interest in hosting LCA in 2013; clusterssh; Openstack compute node cleanup


Syndicated 2012-02-02 16:53:00 from stillhq.com : Mikal, a geek from Canberra living in Silicon Valley (no blather posts)

Shadow of a Dark Queen

ISBN: 9780006480266
I read this book before LCA 2012, but never had a chance to mention it here. It was the first return to Midkemia for me since I read the Krondor's Sons books. This book is set a lot later, and there is very little reuse of characters between The Riftwar Saga or even Krondor's Sons. The only real overlap is the presence of Pug briefly. This book over does its "dirty dozen" aspects, with much of the book focusing on the military training of criminals. The rest of the book feels like a rushed military adventure in a far land, and could have done with some more attention. However, the book isn't terrible, and I thought it was ok overall.

Tags for this post: book raymond_e_feist midkemia combat crime fantasy sword_and_sorcery
Related posts: Daughter of the Empire; The King's Buccaneer; Servant of the Empire; The Riftwar Series; Silverthorn; A Darkness at Sethanon; Mistress of the Empire; Prince of the Blood; Magician: Master; Magician: Apprentice; Raymond E Feist's Empire Trilogy; Polar City Blues; The Stainless Steel Rat Sings The Blues; Dawnspell: The Bristling Wood; Caves of Steel; Currency; Tipping point: windscreen washers; You Can Be The Stainless Steel Rat; Belgarath the Sorcerer; The Adventures of the Stainless Steel Rat; Mona Lisa Overdrive


Syndicated 2012-01-25 22:26:00 from stillhq.com : Mikal, a geek from Canberra living in Silicon Valley (no blather posts)

Are you in a LUG? Do you want some promotional materials for LCA 2013?

Canberra was announced as the host for LCA 2013 at the close of LCA 2012. As part of that closing, we handed out postcards and laptop stickers to delegates. However, we deliberately had extra printed on the theory that groups like LUGs, university computer societies and so forth would be interested in having promotional materials for their groups. For those of you not lucky enough to attend the excellent LCA2012, the stickers looked like this:

And the postcards look like this:

All credit for the excellent art should go to the very capable Jenny Cox. So, if you're interested in having some stuff to hand out at your next LUG or computer society meeting, please drop us a line at contact@lca2013.linux.org.au. Don't forget to include the name of the group and a mailing address.

Tags for this post: conference lca2013 canberra promotion postcard sticker
Related posts: Scoble, I'll buy the damn book, just put your clothes back on; Two more weeks to go; In Canberra; Mont 24 hour race; Most novel traffic jam cause goes to... Canberra!; So, what on earth was I doing up at 4:30 am anyways?; What are we doing with the pets?; Electric shadows has a RSS feed!; Travel details so far; Frank Arrigo discovers Steve Walsh's free wireless; On a bunker kick; linux.conf.au Returns to Canberra in 2013; Calling Tate Needham, or, Hiring in Canberra; LCA weather; Back in Canberra again


Syndicated 2012-01-24 22:24:00 from stillhq.com : Mikal, a geek from Canberra living in Silicon Valley (no blather posts)

linux.conf.au Returns to Canberra in 2013

I am incredibly pleased to announce that linux.conf.au 2013 will be hosted by Canberra, Australia between 28 January 2013 to 2 February 2013. As the director for 2013 I have been blessed with a simply incredible team who has done fantastic work during the bid process, and I am confident that we will pull off a fantastic event. 2013 is Canberra's centenary year, so I think its appropriate to have a conference with a bit of a party atmosphere. We're working hard already on making 2013 a conference to remember.

For those who were unable to see the announcement at the conference, you might find the following interesting:

linux.conf.au is one of the foremost open source conferences in the world, and is considered the most prestigious in the southern hemisphere. Many of the team that brought you linux.conf.au 2005 are coming back to help with the 2013 effort, and we're cognizant of the extremely high standard left by previous conferences, especially the astounding job that Josh's 2012 team did.

The web site for the conference http://lca2013.linux.org.au is already live, and we'll be keeping it up to date as details are locked in.

Tags for this post: conference lca2013 announcement canberra
Related posts: Two more weeks to go; In Canberra; Mont 24 hour race; Most novel traffic jam cause goes to... Canberra!; So, what on earth was I doing up at 4:30 am anyways?; Announcing early results of my survey of SMTP servers; What are we doing with the pets?; Electric shadows has a RSS feed!; Travel details so far; Frank Arrigo discovers Steve Walsh's free wireless; On a bunker kick; Calling Tate Needham, or, Hiring in Canberra; Historical revisionism; LCA weather; Back in Canberra again


Syndicated 2012-01-21 03:10:00 from stillhq.com : Mikal, a geek from Canberra living in Silicon Valley (no blather posts)

It hasn't been a very good week

This week has presented me with a few learning opportunities. Catherine and I are expecting to get a fair few questions about the week, so we thought we'd try and write it up here. That way we can tell people something that's consistent and complete, without having to type the same thing out 200 times. I also think that this topic deserves more space than twitter will allow.

On Wednesday Catherine was told she probably has a brain tumor, and to get an MRI immediately. This was obviously pretty upsetting, and if I've been irritable at you this week that's why and I apologize. Neither of us are medical professionals, and we didn't really know what this meant. Catherine was told that the tumor was "almost certainly" benign, but that wasn't all that reassuring.

Catherine had her MRI the next day. It sounds like a pretty unpleasant process -- your head is clamped into position and an IV fitted, and then you're left in a room which makes the surgical metal in your lower spine feel hot for 40 minutes. Did I mention they clamp your head so you can't escape? Another irritation is that Medicare doesn't cover this MRI at all. So, you take people who have been told they have a brain tumor, and then you tell them that the government doesn't care enough about them to pay for what is considered the best diagnostic for their condition. Better than that, we rang our private insurer, and they told us that Medicare also forbids them to cover it. So, you're out of pocket at least $400.

The MRI report says this: On the right side of the anterior pituitary, there is a hyperintense lesion measuring 9 x 9 x 10mm (T x CC x AP). There is a fluid/fluid level with no definite enhancement of the lesion following contrast injection. The pituitary stalk is minimally bowed to the left. These appearances are in keeping with haemorrhage into a pituitary adenoma.

The first piece of information we had was this paragraph from the MRI company. The GP gets this information about 12 hours before the patient, but our GP was so busy she hadn't read it by the time we did. We saw this about 8pm on Wednesday night, and of course immediately started web searching for the terms in the description. "Hyperintense" for example means "bright white on the MRI", which I believe to be a measure of density of the tumor.

Other learning includes that the pituitary is the gland which moderates the behavior of various elements of the endocrine system, including reproductive hormones. Technically, the pituitary is not part of the brain, but is attached very closely to it.

We saw the GP the next morning (yesterday), and it was mostly reassuring. The tumor is almost certainly not cancer -- I didn't even know there were non-cancerous tumors before yesterday. However, the tumor is affecting Catherine's reproductive hormones, and she is probably sterile for the period the tumor is present. The tumor might also get larger, and if it does it could impact on her optic nerves (which run to either side of the tumor) and that might result in varying levels of vision problems right up to blindness.

It sounds like there are a few courses of action available -- regular MRIs to monitor the state of the tumor. Surgery is an option to have it removed, which is more of an issue if you care about having more children or are suffering from vision disturbances. There are also radio therapy and drug options, but we haven't really had those explained to us yet.

The next steps are for Catherine to see an endocrinologist to see what he thinks about the MRI. Apparently there is a huge waiting list for those in Canberra, so it will mean a trip to Sydney at the end of the month. She also needs to have her vision tested. There's also a huge waiting list for that in Canberra but the specialist she is referred to does waiting list triage, so there is some hope that it wont be too long. We'll know more about that next month.

On a personal note, one of the other things that the last six months has taught me is that I'm not very good at talking about things which are really upsetting me -- our builder going bankrupt leaving us with an unfinished house, my mother in law's ailing health, getting made redundant by Google and this tumor incident being four examples from the last six months. I find I cope much better with these things if I have a chance to internalize them first before I talk to heaps of people about them. So, if I appear standoffish, that's why.

I think its fair for people to have questions about this post, but please remember that we're not experts and we've tried to include everything we know in this post already.

Tags for this post: health catherine brain tumor pituitary adenoma mri
Related posts: JJJ's hack


Syndicated 2012-01-06 16:59:00 from stillhq.com : Mikal, a geek from Canberra living in Silicon Valley (no blather posts)

3 Jan 2012 (updated 3 Jan 2012 at 11:29 UTC) »

Its a good sign that they're already making fun of me, right?

So, today on IRC...

Further adventures with base images in OpenStack

I was bored over the New Years weekend, so I figured I'd have a go at implementing image cache management as discussed previously. I actually have an implementation of about 75% of that blueprint now, but its not ready for prime time yet. The point of this post is more to document some stuff I learnt about VM startup along the way so I don't forget it later.

So, you want to start a VM on a compute node. Once the scheduler has selected a node to run the VM on, the next step is the compute instance on that machine starting the VM up. First the specified disk image is fetched from your image service (in my case glance), and placed in a temporary location on disk. If the image is already a raw image, it is then renamed to the correct name in the instances/_base directory. If it isn't a raw image then it is converted to raw format, and that converted file is put in the right place. Optionally, the image can be extended to a specified size as part of this process.

Then, depending on if you have copy on write (COW) images turned on or not, either a COW version of the file is created inside the instances/$instance/ directory, or the file from _base is copied to instances/$instance.

This has a side effect that had me confused for a bunch of time yesterday -- the checksums, and even file sizes, stored in glance are not reliable indicators of base image corruption. Most of my confusion was because image files in glance are immutable, so how come they differed from what's on disk? The other problem was that the images I was using on my development machine were raw images, and checksums did work. It was only when I moved to a slightly more complicated environment that I had enough data to work out what was happening.

We therefore have a problem for that blueprint. We can't use the checksums from glance as a reliable indicator of if something has gone wrong with the base image. I need to come up with something nicer. What this probably means for the first cut of the code is that checksums will only be verified for raw images which weren't extended, but I haven't written that code yet.

So, there we go.

Tags for this post: openstack cloud computing nova glance qemu image management
Related posts: Openstack compute node cleanup; Playing with StumbleUpon; Why document management is good; Being Geek; Over-analysed Friday comments on Half Nekkid Thursday; Perl sample source code; Old ImageMagick packages in Debian and Ubuntu; Color ebook!; Giving the ACS the benefit of the doubt; Cataloguing meta data against multi media formats; Looking for Women studying computing in Australia; MacOS' RSS screen saver really unreliable?; Supporting more than one browser for your website, or does Firefox really make my life harder?; Life hacking; Scott Adam's blog: the boner theory of management; The architecture of PerlMagick; Gartner recommends blogging over electronic content management; On delegation and event running; The JPEG still picture compression standard; Looking for web form state management; PDF/A


Syndicated 2012-01-02 23:13:00 from stillhq.com : Mikal, a geek from Canberra living in Silicon Valley (no blather posts)

The Ghost Brigades (2)

ISBN: 0765354063
Tor Science Fiction (2007), Edition: First Mass Market Edition May, 2007, Mass Market Paperback, 384 pages
The second time around I think my opinion has changed a little. I found the plot a little hard to believe (perhaps I am scarred by other book's twee explorations of the motivations of alien species), and overall the book not as good as Old Man's War. Then again, its far from the worst book I have read this year.

Original post about this book.

Tags for this post: book john_scalzi combat aliens engineered_human old_mans_war age colonization prometheus award human_backup cranial_computer personal_ai conspiracy
Related posts: The Last Colony ; Old Man's War ; Old Man's War (2); Zoe's Tale; Down and Out in the Magic Kingdom; Buying Time; Broken Angels; Friday ; The Sagan Diary; Saturn's Children; Woken Furies; Ender's Game; Cyteen: The Vindication; Battlefields Beyond Tomorrow ; Mona Lisa Overdrive; The Diamond Age ; Cyteen: The Betrayal; Speaker For The Dead; Red Mars; The System of the World; Cyteen: The Rebirth


Syndicated 2011-12-29 00:57:00 from stillhq.com : Mikal, a geek from Canberra living in Silicon Valley (no blather posts)

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