Killing linux with write-protect tabs
One of our servers is backed up to a 35/70 DLT drive. The other week it started giving us problems, and the drive stopped responding. I obtained a new drive (second-hand ones are cheap), replaced the old one, and everything worked fine... for about a week.

Then the second drive stopped responding. Same symptoms as the first, not showing up on the controller, and all the lights down the left hand side remaining lit after power-up. I'll spare you the details, but after a bit of investigative work I had reason to believe that perhaps our SCSI controller was having difficulty, and not the drive itself.

So, I shell out for a new controller, a sparkly new AHA-29160. These usually sell for $100+ retail, but using the wonders of eBay I picked one up for $20 including express delivery.

Drop in the card, attach the drive, power-up... The DLT drive still shows its lights all down the left-hand side. Damn. Then I notice the SCSI card isn't being recognised during boot. Re-seat the card (it's big!), power cycle. Everything comes up fine.

Boot into single user mode. Linux detects the new card and drive. Drop in an old tape in write-protect mode. Yup, reads it fine. Old data is still there. Happy happy day!

Wanting to perform a backup immediately, and the tape in the drive being the next one due for being overwritten, I wonder if I can flip the write-protect tab while the tape is in the drive... I can!

Sure enough, the light on the DLT panel extinguishes to indicate the tape is available for writing. Sweet. Time to rewind the tape and back-up.

# mt rewind
 
(scsi0:A:6:0): parity error detected in Data-in phase. SEQADDR(0x1a5) SCSIRATE(0x98)
(scsi0:A:6:0): parity error detected in Data-in phase. SEQADDR(0x1a6) SCSIRATE(0x98)
(scsi0:A:6:0): parity error detected in Data-in phase. SEQADDR(0x1a6) SCSIRATE(0x98)
(scsi0:A:6:0): parity error detected in Data-in phase. SEQADDR(0x1a6) SCSIRATE(0x98)

Oh bugger.

I guess I really do need to eject the tape before changing its write-protect status.

Perl tips: 400 subscribers
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Cardiologist consult
Visited the cardiologist today, and was very happy with the service I received. The cardiologist was very patient, very thorough, and very willing to discuss everything. To my delight she was also willing to discuss matters in a more technical fashion at my request. I love learning about how bits of the body work, and the heart is a fascinating organ.

The end result is that yes, I have episodic SVT, and it is everything I could possibly hope for. It does not increase my risk of stroke. It does not exclude me from diving. It is not life threatening. It is not damaging to my heart or any other systems. It can be controlled without medication or surgery. In short, it's an annoyance, and not much more than that.

Woot!

And yes, I can still have caffeine. I should probably consume less than I used to if I want to remain asymptomatic, but I can still have coffee. Even if I do consume too much, then it will be merely annoying.

Double woot!

I've arranged for an ultrasound in a couple of weeks time, just to take a look at my heart to ensure it's structually sound. The cardiologist warned me that about one in three people have a patent foramen ovale (PFO), which is basically a hole between the atria that can re-open during pressure changes in the cardiovascular system. PFOs are associated with greater risks of decompression illness, and so it's recommended that people with PFOs should not dive.

Here's the crazy part. If someone is known to have a PFO, they can't normally be certified as medically fit to dive. If we don't know if someone has a PFO, then they can be certified as medically fit to dive, even though one in three of them won't actually be fit. Some individuals may actively avoid tests that may reveal whether or not they have a PFO, because if they discover they have the condition they won't be allowed to dive anymore.

This is madness, and I'm in agreement with some members of the medical community that a dive medical should include tests to indicate whether or not the patient has a PFO. Of course doing so would crush the diving industry, since they'd lose about one third of their customers.

Needless to say, I'm very happy to be screened for a PFO, and the only reason I haven't been already is due to laziness. If I have the condition, then I'm glad to be giving up diving in exchange for a longer life expectancy, or talking to a doctor of barometric medicine about how to best manage the condition.

Melbourne Perl Mongers AGM

Last night was the Melbourne Perl Mongers AGM. The most interesting piece of news is that Melbourne Perl Mongers Inc (the registered legal body) is likely to be merged into the Open Source Developers Conference Inc, thanks to an ingenious suggestion by Skud. This is somewhat ironic, since MPM Inc was originally created to run the OSDC conference.

The proposed merge has made me very happy. The existence of MPM Inc has made me uneasy for a while; I've felt that the separate committee has made it more difficult for regular members to be involved in meeting organisation, and the additional legal paperwork required is both difficult to understand and complete in a volunteer organisation of our size.

It should be noted that Melbourne Perl Mongers is not going away. Instead there'll be significantly less paperwork and tedious procedure required from those who help organise it, and hopefully a greater inclusion for anyone who wishes to assist in meeting organisation. Overall I view this as a Very Good Thing.

Episodic supraventricular tachycardia
The results from my tests reveal that I appear to have episodic supraventricular tachycardia (SVT). In simple language, my heart sometimes beats too fast for a few seconds, and then returns to normal. The most likely cause is a "wiring fault" involving the electrical impulses that control the heart. There are lots of different faults that can occur, and the exact fault in question is yet to be determined.

The good news is that this isn't ventricular tachycardia which is associated with an increaed chance of sudden death. By comparison, episodic SVT means that I may occasionally feel dizzy for a second or two after heavy exercise. Damn.

SVT isn't a true diagnosis. Instead it's a more accurate description of the symptoms I've been showing. Episodic SVT has been known to disappear by itself, and sometimes may end up being nothing more than an annoyance. On the other hand, SVT may indicate a much more serious problem, or may be a problem in conjunction with other factors, so ignoring it may be a Very Bad Thing. I've arranged for a consultation with a cardiologist this Thursday, at which time I expect to learn a lot more about my condition.

In the meantime, my doctor has recommended that I constrain my intake of caffeine. Apparently filling the heart with stimulants can make everything more excited and induce episodes of SVT. So instead of two large coffees lovingly prepared with my espresso machine each day, I've been insteading having two cups of tea. As expected, I'm getting all te classic symptoms of caffeine withdrawal; irritability, difficulty in concentration, and mild headaches.

The worst thing is, it's working. Since giving up coffee I've experienced no cardiac symptoms whatsoever, so the whole thing may have a really simple fix. I should be thrilled, but I don't really want to give up coffee permanently. Drinking coffee is very high on my list of enjoyable activities.

The good news is that I may be able to resume my old caffeine intake if I have a proceedure that involves burning out parts of my heart with microwave radiation. Hmmm.... tough choice. I'm glad I discovered this before I went and purchased a new espresso machine.

Bloodwork
Bloodwork came back normal. I'm remaining cautiously optimisitic, but have defensively booked a cardiologist appointment anyway.