Yesterday was the big day. I spent more of my day on the train into central London than I did in the exam suite, but only just! The beta exam clocked in at just under 4 hours as they threw more questions at us than you're likely to get in the shipping version of the exam.
And it was tough, too. Two weeks of cramming isn't enough time to get it all down. They're testing knowledge of a lot of subjects across technical, design, and project arenas with a broad mixture of highly conceptual and disturbingly specific questions. Not surprisingly it's all covered in the official exam blueprint, and studying the recommended reading from the blueprint will prepare you for the exam, but in much the same way that reading the entire unabridged edition of the Encyclopaedia Britannica will prepare you for the local pub quiz. There's no substitute for experience here, and my lack of experience with large design projects was a handicap. But I was expecting that.
The beta exam allowed for less than 2 minutes per question which put the pressure on, especially when there were certain classes of interactive question that demanded 5-10 minutes each. Since you have no idea what types of questions are coming, time management is very difficult, particularly towards the end. Do I rush through these multiple choice questions just in case there's a big one coming up, or take a more considered approach and risk running out of time? I went for the former and actually ended up with 8 minutes in hand at the end. It made me feel like I'd chosen wrong.
Frequently I found there wasn't enough space on the screen for the question. It was frustrating to have to answer questions against a scenario when the scenario ran off the right-hand edge of the screen. Worse were the interactive questions that didn't leave enough space on the screen to create an answer. I don't know if this is a general problem or if the testing centre I visited were just running too low a screen resolution. There were a lot of basic proof-reading and clarity of meaning issues.
I doubt it will matter though. I fully expect the exam grade will be based on a weighted sum across different subject areas and a fail in, say, the projecty bit won't make up for good performance in, say, a logical designy bit. On balance, I'm expecting a fail because of my performance on a couple of sections that I just don't have enough background in to feel confident in.
The afterward made it sound like only those who passed would be contacted once VMware had had time to collate and review all the beta test scores, so I may never know just how badly I've done :)
Friday, 12 November 2010
Tuesday, 26 October 2010
VCAP DCD Exam Beta
Last week I unexpectedly received, from VMware, an invitation to sit the beta VCAP4 Datacentre Design exam. It comes at a discount rate, but with an obligation to provide feedback on the exam itself.
From the wording of the email it seems anyone with a VCP4 is eligible to sit the beta exam, so I'm not sure if I won a lottery for this or if everyone's had an invitation.
Whatever the cause, I've booked myself in for the 11th of November, and will be spending most nights between now and then with a copy of the exam blueprint and a stern resolve.
From the wording of the email it seems anyone with a VCP4 is eligible to sit the beta exam, so I'm not sure if I won a lottery for this or if everyone's had an invitation.
Whatever the cause, I've booked myself in for the 11th of November, and will be spending most nights between now and then with a copy of the exam blueprint and a stern resolve.
Friday, 22 October 2010
New Stuff
I've made a few acquisitions in the last month.
Tomorrow morning I'm off to the post office to pick up a pack of assorted Fuizion freeze dried food sachets, which everyone seems to have been raving about.
I've ordered a Glo-Toob FX for small, lightweight in-tent lighting. I've heard good things about them and as it's always a pain to create ambient light with a head torch, which are usually very directional by design, I'm looking forward to seeing how it performs. Whether it's bright enough to read by remains to be seen, but I live in hope.
On a similar note, I've added a Petzl Tikka2 XP to my collection as well. I actually quite like my dirt cheap Energizer LED torch that I got for £5 at a Millets in Oban and have never seen sold anywhere since. But I've started cycling in to work now and the throw wouldn't be long enough to see where I was going on a dark winter's evening. I'm delighted with the effectiveness of the Petzl's diffuser, but slightly irritated by the noticeable flickering of the LEDs in economy mode.
I wish I could afford a decent insulated jacket so I can get out in the dead of winter. I'm looking at you, PHD Minimus jacket. And by decent I of course mean top of the line. Ahem.
Tomorrow morning I'm off to the post office to pick up a pack of assorted Fuizion freeze dried food sachets, which everyone seems to have been raving about.
I've ordered a Glo-Toob FX for small, lightweight in-tent lighting. I've heard good things about them and as it's always a pain to create ambient light with a head torch, which are usually very directional by design, I'm looking forward to seeing how it performs. Whether it's bright enough to read by remains to be seen, but I live in hope.
On a similar note, I've added a Petzl Tikka2 XP to my collection as well. I actually quite like my dirt cheap Energizer LED torch that I got for £5 at a Millets in Oban and have never seen sold anywhere since. But I've started cycling in to work now and the throw wouldn't be long enough to see where I was going on a dark winter's evening. I'm delighted with the effectiveness of the Petzl's diffuser, but slightly irritated by the noticeable flickering of the LEDs in economy mode.
I wish I could afford a decent insulated jacket so I can get out in the dead of winter. I'm looking at you, PHD Minimus jacket. And by decent I of course mean top of the line. Ahem.
Friday, 1 October 2010
TarpTent Scarp 1: First impressions
I got my Scarp 1 yesterday, merely a week after ordering it from the US. I emailed Henry the day after I ordered it politely inquiring if I'd be lucky enough to receive a tent out of the fresh batch of Scarps that had just arrived. Henry replied the same day - he'd already shipped it!
I spent the best part of the week refreshing the USPS parcel tracking page.
Anyway, on to the unboxing. My first impressions of the tent in the bag but out of the box was that it seemed heavier, and larger than I was hoping for. It turns out this was an illusion. In a straight hand-holding test it's practically the same weight as my Eureka Spitfire 1 tent, maybe lighter. I havent put it on the scales.
The reason the size threw me is that for the last few months I've been stuffing my Spitfire into a compression sack and compressing the hell out of it until it's the size of a large grapefruit, and packing the poles and pegs separately. So last night, for comparisson's sake I repacked my Spitfire in its original bag to find it's about 20% fatter than the Scarp 1, if the same length. That's nice.
I won't be able to pack the Scarp 1 down the way I did the Spitfire because of the carbon rods at the ends that give the tent its corner structure, much like you can see in the Akto and Laser tents. You can take the rods out of course (to replace them if they break I guess) but there are 10 of them and that's a massive faff. It just means I need to think differently the next time I pack.
I had just enough space in my bedroom to set the tent up in its free-standing mode! Setup in this fashion is a breeze, and very intuitive. I'm sure the more common staking mode is just as easy. Henry provides a simple set of printed instructions and once you unfurl the tent it's easy to see how the corner and end support structures work.
This is a well thought-out tent. There are lots of venting options; one at each end, and the top vents, and the side of the fly slides up the main arch pole as well, and while I was initially put out by the lack of a double-zip on the fly doors I think it's compensated for by the presence of the clip and velcro patch at the base of the door so you can have the door unzipped the whole way but kept mostly closed by these fixing points.
The inner is suspended from the fly at a number of hanging points, but the base of the inner is floating in that it has no ground attachments of its own. It's a bit tricky (almost impossible?) to get to the end vents from inside the tent without detatching the inner first, but that's not hard.
The vestibules are quite narrow, but there are two of them, so I'm thinking that one of them can basically stay empty for cooking and whatnot, with kit stashed in the other. Also, the floating inner means it can be pegged back easily to make more room as others have already done.
I'd read about the huge amount of space inside before buying so I was expecting big things. But it's not that big. It's bigger than the Spitfire of course, and with the straight walls, more of it is usable. I guess that never having owned a Laser Comp I don't have the same perspective. Don't get me wrong, there's room, but once you start bringing clothes and gear inside your sleeping mat is going to start getting cozy with it all. But with all that vertical space it won't feel crowded.
All I need now is some silicone and a spare couple of hours to seal the seams and I can get out and use it.
So far I'm still excited about the tent, and I'm looking forward to finishing it up and getting outside with it for the first time.
I spent the best part of the week refreshing the USPS parcel tracking page.
Anyway, on to the unboxing. My first impressions of the tent in the bag but out of the box was that it seemed heavier, and larger than I was hoping for. It turns out this was an illusion. In a straight hand-holding test it's practically the same weight as my Eureka Spitfire 1 tent, maybe lighter. I havent put it on the scales.
The reason the size threw me is that for the last few months I've been stuffing my Spitfire into a compression sack and compressing the hell out of it until it's the size of a large grapefruit, and packing the poles and pegs separately. So last night, for comparisson's sake I repacked my Spitfire in its original bag to find it's about 20% fatter than the Scarp 1, if the same length. That's nice.
I won't be able to pack the Scarp 1 down the way I did the Spitfire because of the carbon rods at the ends that give the tent its corner structure, much like you can see in the Akto and Laser tents. You can take the rods out of course (to replace them if they break I guess) but there are 10 of them and that's a massive faff. It just means I need to think differently the next time I pack.
I had just enough space in my bedroom to set the tent up in its free-standing mode! Setup in this fashion is a breeze, and very intuitive. I'm sure the more common staking mode is just as easy. Henry provides a simple set of printed instructions and once you unfurl the tent it's easy to see how the corner and end support structures work.
This is a well thought-out tent. There are lots of venting options; one at each end, and the top vents, and the side of the fly slides up the main arch pole as well, and while I was initially put out by the lack of a double-zip on the fly doors I think it's compensated for by the presence of the clip and velcro patch at the base of the door so you can have the door unzipped the whole way but kept mostly closed by these fixing points.
The inner is suspended from the fly at a number of hanging points, but the base of the inner is floating in that it has no ground attachments of its own. It's a bit tricky (almost impossible?) to get to the end vents from inside the tent without detatching the inner first, but that's not hard.
The vestibules are quite narrow, but there are two of them, so I'm thinking that one of them can basically stay empty for cooking and whatnot, with kit stashed in the other. Also, the floating inner means it can be pegged back easily to make more room as others have already done.
I'd read about the huge amount of space inside before buying so I was expecting big things. But it's not that big. It's bigger than the Spitfire of course, and with the straight walls, more of it is usable. I guess that never having owned a Laser Comp I don't have the same perspective. Don't get me wrong, there's room, but once you start bringing clothes and gear inside your sleeping mat is going to start getting cozy with it all. But with all that vertical space it won't feel crowded.
All I need now is some silicone and a spare couple of hours to seal the seams and I can get out and use it.
So far I'm still excited about the tent, and I'm looking forward to finishing it up and getting outside with it for the first time.
Friday, 10 September 2010
A lighter load, and the rest
I managed to get out on dartmoor twice the weekend before last; once on the Friday night for a quick getaway, and more seriously on the Sunday night where Jackie and I managed a 12 mile round-trip hike.
I'm excited because a few recent purchases (ThermaRest Prolite, Montane Featherlite) and a slightly more ruthless approach to packing has reduced the weight of my pack by a couple of kilograms, but the best part is that with a cheap compression sack my Eureka Spitfire tent takes up a lot less room and I can now fit back in to my much lighter 45L Osprey pack for one or two-day trips instead of the massive and heavy 65+10L Berghaus beast.
A one-man tent with a decent vestibule is still high on my wishlist so I can drop the tarp I'm currently using to make a verandah, and as Jackie's more enthusiastic about nights away than I thought she might be, I'd really like to find a larger, lighter alternative to the depressingly pokey, cheap, and disproportionately heavy Millets special two-man tent we have to lug around at the moment.
I originally had my sights set on the venerable Terra-Nova Laser Comp, but I've been put off recently by questions about its stability in high-wind, what with nothing to support the tunnel structure and only a single end-guy. But it's still one of the best weight-to-room ratio tents that (my kind of) money can buy.
For a two-man, I'm tempted by a tarptent design. But again, the poor hydrostatic-head of silicon impregnated nylon is a worry - not so much for the fly, but the floor. So you start having to lug about a footprint just to keep the floor dry.
Anyway, I need to move on the one-man tent soon. The Eureka's all-mesh inner won't cut it as the temperature drops.
I'm excited because a few recent purchases (ThermaRest Prolite, Montane Featherlite) and a slightly more ruthless approach to packing has reduced the weight of my pack by a couple of kilograms, but the best part is that with a cheap compression sack my Eureka Spitfire tent takes up a lot less room and I can now fit back in to my much lighter 45L Osprey pack for one or two-day trips instead of the massive and heavy 65+10L Berghaus beast.
A one-man tent with a decent vestibule is still high on my wishlist so I can drop the tarp I'm currently using to make a verandah, and as Jackie's more enthusiastic about nights away than I thought she might be, I'd really like to find a larger, lighter alternative to the depressingly pokey, cheap, and disproportionately heavy Millets special two-man tent we have to lug around at the moment.
I originally had my sights set on the venerable Terra-Nova Laser Comp, but I've been put off recently by questions about its stability in high-wind, what with nothing to support the tunnel structure and only a single end-guy. But it's still one of the best weight-to-room ratio tents that (my kind of) money can buy.
For a two-man, I'm tempted by a tarptent design. But again, the poor hydrostatic-head of silicon impregnated nylon is a worry - not so much for the fly, but the floor. So you start having to lug about a footprint just to keep the floor dry.
Anyway, I need to move on the one-man tent soon. The Eureka's all-mesh inner won't cut it as the temperature drops.
Thursday, 2 September 2010
More on SSD longevity
This whitepaper published by Western Digital is an interesting read and provides a couple of well thought-out equations for estimating SSD life with a known workload.
The trick is knowing your workload, and fitting it to the simple parameters in the WD LifeEST model.
The trick is knowing your workload, and fitting it to the simple parameters in the WD LifeEST model.
Wednesday, 1 September 2010
Exchange and SSDs
I'm designing an Exchange 2010 system at the moment as an upgrade from a clustered Exchange 2003 environment.
I won't go in to the details about the restrictions in the current system, save to say that even after having lots of physical spindles thrown at it, it's still IO bound.
So the new system is going to have SSD. And what a lot of fun that's turning out to be. Try finding some hard data on the life expectency of MLC SSDs under genuine enterprise (i.e. not desktop) workloads. Go on, I dare you. I'd settle for real-world life expectencies of MLC drives full stop.
Instead, everyone's throwing around the 10,000 program/erase cycle design spec with a caution to keep an eye on it, and the vendors seem reluctant to let go any real information how many writes you can expect to get away with before hard errors start to crop up.
Use SLC you say? Fair enough, but until the cost per GB comes down it's still likely to be more cost effective to burn through a couple of same-size MLCs on a price per GB per year equation. I think. See above re: vagaries of predicting drive failure.
Either SSD is still finding its feet in the enterprise space, or people just aren't writing about it yet. Or maybe the drives just haven't started to fail.
Reliability will improve as the technology continues to mature, and it's maturing fast. Even if I only get 6 months before the first drives start to burn out, which I think is exceedingly pessimistic, the replacement drives are likely to be hardier, and cheaper even then.
Anyway, I'm looking forward to getting of the design sheet on this one and starting to push bytes around. Stay tuned.
I won't go in to the details about the restrictions in the current system, save to say that even after having lots of physical spindles thrown at it, it's still IO bound.
So the new system is going to have SSD. And what a lot of fun that's turning out to be. Try finding some hard data on the life expectency of MLC SSDs under genuine enterprise (i.e. not desktop) workloads. Go on, I dare you. I'd settle for real-world life expectencies of MLC drives full stop.
Instead, everyone's throwing around the 10,000 program/erase cycle design spec with a caution to keep an eye on it, and the vendors seem reluctant to let go any real information how many writes you can expect to get away with before hard errors start to crop up.
Use SLC you say? Fair enough, but until the cost per GB comes down it's still likely to be more cost effective to burn through a couple of same-size MLCs on a price per GB per year equation. I think. See above re: vagaries of predicting drive failure.
Either SSD is still finding its feet in the enterprise space, or people just aren't writing about it yet. Or maybe the drives just haven't started to fail.
Reliability will improve as the technology continues to mature, and it's maturing fast. Even if I only get 6 months before the first drives start to burn out, which I think is exceedingly pessimistic, the replacement drives are likely to be hardier, and cheaper even then.
Anyway, I'm looking forward to getting of the design sheet on this one and starting to push bytes around. Stay tuned.
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