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.

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.

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.