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Programming

Journal Journal: On coding 8

Object orientation and code readability are mostly mutually exclusive.
User Journal

Journal Journal: The perils of progress 5

Ever increasing storage capacity is making me lazy. In years gone by, when resources were more limited, a full filesystem would be cause for investigation, to find out why it had become full, and what could be done about it. These days, the easy option is to just extend the volume a bit more and grow the filesystem. I'm running a bit low on free PV space, so last week I didn't grow my home filesystem by as much as I normally would when it filled up. But even so, I was a little surprised to find out that within a couple of days it was already full again. That's not normal. It turned out that a single log file was continually growing and had taken up nearly a third of the total space on that filesystem. But because the default assumption is that I have more disk space than I'll be able to use, I hadn't been keeping an eye on what was taking up the space. D'oh! So a single rm has taken me back to having loads of free space.

User Journal

Journal Journal: Farewell Libya 17

So Libya has cut itself off from the net. This isn't an entirely unexpected move. But it has the side effect of screwing over anyone with a .ly domain. The main loser there is probably bit.ly. It still seems to be up at the moment, but I'm guessing that DNS caches will expire soon enough and then they'll be in trouble.

But somehow I just can't find it in me to feel any sympathy for them. At the time they launched, I pointed out that they were putting themselves at the mercy of the Libyan government. But it seems they preferred the two digit .ly ccTLD to the three digit .com domain they could have used instead. There are times when convenience trumps reliability. But this wasn't one of them. I wasn't expecting it to go wrong as quickly as it did, but I was aware of the possibility. It seems they either weren't aware of it, or chose to ignore the risk. That wasn't the wisest move in the world, even without the benefit of hindsight.

Maybe it'll act as a warning to those who have jumped on the .co bandwagon recently. But I doubt it. So I won't be surprised if the Colombian government screws them over at some point, in the same way the Libyan government has just done. And I won't have any sympathy for them, either.

Social Networks

Journal Journal: Twitter

Err... what? It seems that twitter requires you to have Javascript enabled in order to view 140 characters of someone's worthless drivel. Otherwise you get a blank page. The mind boggles.
Hardware Hacking

Journal Journal: ...and then there was silence

Once you've been around computers for a while, you get to recognise certain sounds. Such as the pop followed by the spinning down of fans, and the ominous silence that emanates from the box that's supposed to be your fileserver. Arse. I was off work yesterday due to a nasty cold, and the last thing I wanted to be doing was rebuilding the server. Fortunately, it turned out to be just the power supply. I'd been worried that it was going to have taken out the motherboard too. It did take a hard drive with it on the way out, but fortunately that wasn't fatal. The RAID rebuild ran OK overnight, and now we're back to normal.
Graphics

Journal Journal: Zooming/panning images for video 2

Does anyone know of a good solution for zooming/panning static images for turning into a video? The so called Ken Burns effect? It must work on Linux, and should ideally be open source. The pan in openshot doesn't seem to work, and the zoom is too jerky to be useful. I can write my own fairly easily if I have to, but I'd rather not reinvent the wheel if I can avoid it.
User Journal

Journal Journal: Oops 2

Today I learned that my window manager hotkey to bring the focused window to the front doesn't work when the thing that's obscuring the window in question is a post-it note on the monitor. D'oh!
The Matrix

Journal Journal: The WebM project 2

http://www.webmproject.org

It's what we were all hoping for, and I'm pleased that it's come to pass. It's not perfect, and I don't agree with all of their decisions. However, even an imperfect alternative to the current H.264 situation is a massive improvement. I'm pleased they've gone for a full stack solution of not only VP8 but also Matroska(-ish) and Vorbis, too. If nothing else, it's likely to mean that a) Vorbis will be shipped by default on most platforms[1], and b) hardware support for both VP8 and Vorbis should be widespread in the very near future. Further, there's a commitment to transcode all of the existing videos on YouTube. That's a massive endorsement. Of course, the risk with that is the reduced quality that will come from three or more lossy transforms, but given that they've announced it, they're clearly not too concerned about that. The future's looking very bright indeed.

[1] Or will it? I've yet to see any official response from Microsoft or Apple on this. But it's going to be hard for them to ship something that won't play YouTube videos by default. Of course, in the short and probably medium term, YouTube will continue to offer videos in other formats as well. But we'll see how it plays out in the long term.

Silicon Graphics

Journal Journal: I want a bigger computer 10

I went to an interesting talk by Eng Lim Goh of SGI on Thursday, demonstrating their Ultraviolet systems. Very cool. While there are bigger and faster computers on the planet, they're all technically clusters rather than a single computer. The SGI machines can have 4096 CPUs and 16TB of RAM running under a single Linux kernel. Nice.

Also interesting to see the stats on when their systems were delivered to McLaren and Brawn, and where the performance of those cars was afterwards. I know there's more to F1 than CFD, but it certainly plays a large part these days.

Open Source

Journal Journal: About time too 1

The UK's Information Commissioner has ruled that research data must be made public. I have little sympathy for the likes of Keenan. But I have even less sympathy for so called scientists who refuse to make their data available for others to study. This isn't just about climate change, either, but about science in general. The recent spate of falsified results in Chinese and Korean papers should be ample evidence that data needs to be made public so that results can be independently verified. That's what science is all about.
Shark

Journal Journal: Anyone know about ATA errors? 7

My backup failed last night, because the device was read only:

building file list ... done
rsync: delete_file: unlink "/backup/local/shared/camera/2009-08-24--foq/img_0507.jpg" failed: Read-only file system (30)
rsync: delete_file: unlink "/backup/local/shared/camera/2009-08-24--foq/.xvpics/img_0507.jpg" failed: Read-only file system (30)

That's never a good sign. Looking through the logs, I see a number of ATA errors, starting with a timeout, a device error, and a bunch of HSM violations. A few examples:

Mar 22 07:56:03 riva kernel: ata2.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x6 frozen
Mar 22 07:56:03 riva kernel: ata2.00: cmd 25/00:00:87:d1:86/00:02:03:00:00/e0 tag 0 dma 262144 in
Mar 22 07:56:03 riva kernel: res 40/00:00:00:00:00/ff:ff:ff:ff:ff/00 Emask 0x4 (timeout)
Mar 22 07:56:03 riva kernel: ata2.00: status: { DRDY }
Mar 22 07:56:03 riva kernel: ata2: hard resetting link
Mar 22 07:56:03 riva kernel: ata2: SATA link up 1.5 Gbps (SStatus 113 SControl 310)
Mar 22 07:56:03 riva kernel: ata2.00: configured for UDMA/33
Mar 22 07:56:03 riva kernel: ata2: EH complete
Mar 22 07:56:03 riva kernel: SCSI device sdb: 1465149168 512-byte hdwr sectors (750156 MB)
Mar 22 07:56:03 riva kernel: sdb: Write Protect is off
Mar 22 07:56:03 riva kernel: SCSI device sdb: drive cache: write back

Mar 22 07:59:05 riva kernel: ata2.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x0
Mar 22 07:59:05 riva kernel: ata2.00: BMDMA2 stat 0x6d0009
Mar 22 07:59:05 riva kernel: ata2.00: cmd 25/00:00:df:ce:87/00:02:03:00:00/e0 tag 0 dma 262144 in
Mar 22 07:59:05 riva kernel: res 51/04:80:5f:cf:87/00:01:03:00:00/e0 Emask 0x1 (device error)
Mar 22 07:59:05 riva kernel: ata2.00: status: { DRDY ERR }
Mar 22 07:59:05 riva kernel: ata2.00: error: { ABRT }
Mar 22 07:59:05 riva kernel: ata2.00: configured for UDMA/33
Mar 22 07:59:05 riva kernel: ata2: EH complete
Mar 22 07:59:05 riva kernel: SCSI device sdb: 1465149168 512-byte hdwr sectors (750156 MB)
Mar 22 07:59:05 riva kernel: sdb: Write Protect is off
Mar 22 07:59:05 riva kernel: SCSI device sdb: drive cache: write back

Mar 22 08:01:15 riva kernel: ata2.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x6 frozen
Mar 22 08:01:15 riva kernel: ata2.00: cmd 25/00:00:ff:1e:88/00:02:03:00:00/e0 tag 0 dma 262144 in
Mar 22 08:01:15 riva kernel: res ff/ff:ff:ff:ff:ff/ff:ff:ff:ff:ff/ff Emask 0x2 (HSM violation)
Mar 22 08:01:15 riva kernel: ata2.00: status: { Busy }
Mar 22 08:01:15 riva kernel: ata2.00: error: { ICRC UNC IDNF ABRT }
Mar 22 08:01:15 riva kernel: ata2: hard resetting link
Mar 22 08:01:15 riva kernel: ata2: SATA link up 1.5 Gbps (SStatus 113 SControl 310)
Mar 22 08:01:15 riva kernel: ata2.00: configured for UDMA/33
Mar 22 08:01:15 riva kernel: ata2: EH complete
Mar 22 08:01:15 riva kernel: SCSI device sdb: 1465149168 512-byte hdwr sectors (750156 MB)
Mar 22 08:01:15 riva kernel: sdb: Write Protect is off
Mar 22 08:01:15 riva kernel: SCSI device sdb: drive cache: write back

SMART doesn't seem to be much help here, with the device refusing to run anything but the mandatory offline test:

riva:~# smartctl --test=offline /dev/sdb
smartctl version 5.36 [i686-redhat-linux-gnu] Copyright (C) 2002-6 Bruce Allen
Home page is http://smartmontools.sourceforge.net/

Default Self Test Successful
riva:~# smartctl --test=short /dev/sdb
smartctl version 5.36 [i686-redhat-linux-gnu] Copyright (C) 2002-6 Bruce Allen
Home page is http://smartmontools.sourceforge.net/

Short offline self test failed [unsupported field in scsi command]
riva:~# smartctl --test=long /dev/sdb
smartctl version 5.36 [i686-redhat-linux-gnu] Copyright (C) 2002-6 Bruce Allen
Home page is http://smartmontools.sourceforge.net/

Long (extended) offline self test failed [unsupported field in scsi command]

It's a Seagate drive:

Host: scsi1 Channel: 00 Id: 00 Lun: 00
Vendor: ATA Model: ST3750528AS Rev: CC38
Type: Direct-Access ANSI SCSI revision: 05

I'm running 2.6.18-128.4.1.el5 on CentOS 5.

Any ideas? Does anyone know enough about the ATA spec to tell me what these errors actually mean? Is this a genuine hardware failure? If so, where's it likely to be? Drive? Controller? Cable? The drive is only a few weeks old, so while sometimes shit happens, I want to investigate the (probably more likely) alternatives as well.

Google

Journal Journal: Web development woes 3

How can I get a <td> to be a containing block? Section 10.1 of the spec implies that just giving it position: relative; should be sufficient. But that's completely bypassed, and the search carries on up the element hierarchy. I kludged it by putting a relatively positioned <div> inside the cell, but it's frustrating to have to resort to such workarounds. Anyone know why it didn't work? There's no mention in the spec of table elements being given special treatment when it comes to containing blocks. Indeed, it explicitly mentions that table cells should work. But they don't (in Firefox 3 and Opera 10, at least).

And why oh why doesn't <tbody> nest? I want to refer to part of a table and manipulate it with some Javascript (mostly just to show or hide it in response to user actions). But I can't just stick the relevant bits in a <tbody> and select by that because the table already contains several tbodies. Thus I'm once again stuck in workaround hell, trying to tag each tbody with an appropriate class, so I can iterate over them and check if I'm interested in each one. Further, because I'm dynamically adding and removing parts of the table, I need to check at the time I add to the table whether the bit I'm adding should be visible or not. Life would be so much easier if I could just stick it in an appropriate <tbody> further up the hierarchy, and then mark the whole lot visible or otherwise. But I guess that would be far too easy :-(

Portables

Journal Journal: Finding the right laptop 7

The time has come for a new laptop. But how do I find the right one? My requirements are minimal. Namely, I need a large screen, decent battery life and a low price. Surely there must be a laptop comparison site somewhere that lets me enter my specs and it'll give some recommendations, right? Yes, I can go to Toshiba's site and there's a great tool that does exactly that. Dell's and Acer's are adequate but not quite as good as Toshiba, and HP don't have one at all. But all of them are restricted to a single brand (as you'd expect). Where is the cross brand equivalent? Further, there are no doubt brands I've never heard of that I might be interested in, and without knowing who they are, I can't go to their web sites to check their offerings even if I wanted to.

Any CPU will be more than sufficient for my needs. The screen needs to be at least 17", and not gloss (which sadly seems to rule out the otherwise promising models from Samsung). I need 2GB RAM, and I don't want to be paying more than £500. A bit of digging reveals that all of the major players have models that meet those requirements. But I still have the nagging feeling that I'm missing out of the "right" model simply because I don't know about it. Where should I be looking?

Oh, and it won't have an Apple badge, so don't even consider suggesting that...

Networking

Journal Journal: Policy routing

I don't know why, but I always get a warm feeling when I configure policy routing. Under Linux, iproute2 makes it almost trivially easy, so there isn't any real reason for it, but when I see my packets going off where I tell them to, I always seem to have a sense of accomplishment that's disproportionate to the amount of difficulty involved.

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