Generic indexed storage for TUNGSTEN (by alaric)

For TUNGSTEN, I plan to split the local storage manager into two layers; the physical manager and the logical managers. The physical manager takes a collection of block storage devices (such as hard disks), and a configuration giving advice on which disks to use for what, and provides an administrative interface for modifying said configuration and monitoring usage, and an interface to the logical managers. The latter interface provides access to a single unified associative data store; the local store is divided into regions for each volume mirrored on the local node (by a numeric volume ID), which are in turn divided into regions for each entity (by a numeric entity ID), which are in turn divided into regions for each object within the entity (by a numeric object ID), which may then be structured as the logical manager responsible for that object sees fit. The structure available to the logical manager within an object is a set of records, each with a key and a value. The physical manager provides the ability to create, abort, or commit transactions, and within a transaction, read, write, add, and remove records, including iterating through records by key range.

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Venti: Append-Only Storage Management (by alaric)

Check out this PDF:

http://www.cs.bell-labs.com/sys/doc/venti/venti.pdf

It's a description of a new mass storage system designed for Plan 9. Venti offers permanent archival storage, with basically two operations:

1. Given a block of up to 52KB of data (and some metadata, which is fairly irrelevant), the system returns an SHA1 hash of that data

2. Given an SHA1 hash, return the previously stored block of data with that hash.

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Coal fire (by alaric)

One of the definite plusses of living in a proper village is that we have a local blacksmith.

Now, our house has a dual-fuel burner that, with a grate in, can burn coal, or without the grate is for wood. Sadly, the grate was a molten blob; it looked like somebody had tried to light a fire with liquid oxygen...

So we took it up to said blacksmith, who for a mere twenty pounds made it as good as new. We were given a bag of coal as a thank-you present from somebody, so using my military surplus trenching tool as an ash shovel and a pair of spoons as impromptu tongs, we've had coal fire for two days in a row now.

Why coal, you may ask, when we can go and pick up free firewood from the grounds? Well, the rate we get through wood makes it look doubtful we could manage purely on gathered wood, plus it saves a lot of time to not have to gather and chop the wood. We still need wood to get the fire started, so it's not like the wood will go to waste; but rather than buying extra wood, as we were, we'll spend less buying coal and take up less space storing it.

Indeed, we've used barely the top quarter of a small sack of coal so far; in the same time, we'd have burned up a fair pile of logs, involving more work feeding them in regularly, and more heat lost to evaporating the water in the wood. And I grew up with coal; it's familiar to me, and I find it easy to regulate.

However, when I went outside just now to put things on the compost heap, I realised that our house now has whiffs of the smell of coal smoke around it - smells that fondly remind me of visiting Wales!

Snuffles (by alaric)

Jean has a cold! Her first taste of sickness.

She's snuffling and sneezing and coughing, and her eyes are puffed and watering, but she's not letting it get her down - she's a bit grumpier than usual, but she still smiles at us and her toys! I'm quite impressed; I don't think I could be very cheery if I felt as rough as she looks.

We're keeping her well supplied with Karvol (stuff for children that releases menthol vapours) and trying to keep her warm and comfortable.

Nooooo! Van!!! (by alaric)

Just had a phonecall from the friend who was borrowing our lovely van - he was just driving it back, when it made rattling noises, so he pulled over and now it won't start 🙁

The fear is that it may have run out of oil and seized, since it has a known propensity to get through oil fast (as many old diesels do). However, no warning light came on.

Please be OK, van!

= UPDATE =

Looks like it did run out of oil; the engine's all seized up inside.

However, luckily, Sarah's uncle is a mechanical engineer, and has managed to find us a nice Transit engine that's even newer than the one in the van - and he can install it for us! So the van is going to have something of an upgrade to a turbo diesel engine - a new lease of life...

Phew!